builtins: Add firstLeadingBit

Currently polyfilled for all backends.
HLSL should be able to map this to 'firstbithigh', but there might need
to be some special case handling for 0 (undocumented behavior). For now
just polyfill.

CTS tests: https://github.com/gpuweb/cts/pull/1004

Bug: tint:1367
Bug: tint:1449
Change-Id: I9c9a08ea93d1c4a602e0ab763e95e2eea336fb0d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/81503
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/builtins.def

@@ -316,6 +316,8 @@ fn exp<N: num>(vec<N, f32>) -> vec<N, f32>
 fn exp2(f32) -> f32
 fn exp2<N: num>(vec<N, f32>) -> vec<N, f32>
 fn faceForward<N: num>(vec<N, f32>, vec<N, f32>, vec<N, f32>) -> vec<N, f32>
+fn firstLeadingBit<T: iu32>(T) -> T
+fn firstLeadingBit<N: num, T: iu32>(vec<N, T>) -> vec<N, T>
 fn firstTrailingBit<T: iu32>(T) -> T
 fn firstTrailingBit<N: num, T: iu32>(vec<N, T>) -> vec<N, T>
 fn floor(f32) -> f32

src/tint/program_builder.h

@@ -1596,6 +1596,15 @@ class ProgramBuilder {
                                           Expr(std::forward<EXPR>(expr)));
   }
 
+  /// @param expr the expression to perform a unary complement on
+  /// @return an ast::UnaryOpExpression that is the unary complement of the
+  /// input expression
+  template <typename EXPR>
+  const ast::UnaryOpExpression* Complement(EXPR&& expr) {
+    return create<ast::UnaryOpExpression>(ast::UnaryOp::kComplement,
+                                          Expr(std::forward<EXPR>(expr)));
+  }
+
   /// @param source the source information
   /// @param func the function name
   /// @param args the function call arguments

src/tint/sem/builtin_type.cc

@@ -117,6 +117,9 @@ BuiltinType ParseBuiltinType(const std::string& name) {
   if (name == "faceForward") {
     return BuiltinType::kFaceForward;
   }
+  if (name == "firstLeadingBit") {
+    return BuiltinType::kFirstLeadingBit;
+  }
   if (name == "firstTrailingBit") {
     return BuiltinType::kFirstTrailingBit;
   }
@@ -410,6 +413,8 @@ const char* str(BuiltinType i) {
       return "exp2";
     case BuiltinType::kFaceForward:
       return "faceForward";
+    case BuiltinType::kFirstLeadingBit:
+      return "firstLeadingBit";
     case BuiltinType::kFirstTrailingBit:
       return "firstTrailingBit";
     case BuiltinType::kFloor:

src/tint/sem/builtin_type.h

@@ -63,6 +63,7 @@ enum class BuiltinType {
   kExp,
   kExp2,
   kFaceForward,
+  kFirstLeadingBit,
   kFirstTrailingBit,
   kFloor,
   kFma,

src/tint/transform/builtin_polyfill.cc

@@ -55,10 +55,7 @@ struct BuiltinPolyfill::State {
       return b.ty.vec<ProgramBuilder::u32>(width);
     };
     auto V = [&](uint32_t value) -> const ast::Expression* {
-      if (width == 1) {
+      return ScalarOrVector(width, value);
-        return b.Expr(value);
-      }
-      return b.Construct(b.ty.vec<ProgramBuilder::u32>(width), value);
     };
     b.Func(
         name, {b.Param("v", T(ty))}, T(ty),
@@ -120,10 +117,7 @@ struct BuiltinPolyfill::State {
       return b.ty.vec<ProgramBuilder::u32>(width);
     };
     auto V = [&](uint32_t value) -> const ast::Expression* {
-      if (width == 1) {
+      return ScalarOrVector(width, value);
-        return b.Expr(value);
-      }
-      return b.Construct(b.ty.vec<ProgramBuilder::u32>(width), value);
     };
     auto B = [&](const ast::Expression* value) -> const ast::Expression* {
       if (width == 1) {
@@ -176,6 +170,87 @@ struct BuiltinPolyfill::State {
     return name;
   }
 
+  /// Builds the polyfill function for the `firstLeadingBit` builtin
+  /// @param ty the parameter and return type for the function
+  /// @return the polyfill function name
+  Symbol firstLeadingBit(const sem::Type* ty) {
+    auto name = b.Symbols().New("tint_first_leading_bit");
+    uint32_t width = WidthOf(ty);
+
+    // Returns either u32 or vecN<u32>
+    auto U = [&]() -> const ast::Type* {
+      if (width == 1) {
+        return b.ty.u32();
+      }
+      return b.ty.vec<ProgramBuilder::u32>(width);
+    };
+    auto V = [&](uint32_t value) -> const ast::Expression* {
+      return ScalarOrVector(width, value);
+    };
+    auto B = [&](const ast::Expression* value) -> const ast::Expression* {
+      if (width == 1) {
+        return b.Construct<bool>(value);
+      }
+      return b.Construct(b.ty.vec<bool>(width), value);
+    };
+
+    const ast::Expression* x = nullptr;
+    if (ty->is_unsigned_scalar_or_vector()) {
+      x = b.Expr("v");
+    } else {
+      // If ty is signed, then the value is inverted if the sign is negative
+      x = b.Call("select",                             //
+                 b.Construct(U(), "v"),                //
+                 b.Construct(U(), b.Complement("v")),  //
+                 b.LessThan("v", ScalarOrVector(width, 0)));
+    }
+
+    b.Func(name, {b.Param("v", T(ty))}, T(ty),
+           {
+               // var x = v;                          (unsigned)
+               // var x = select(U(v), ~U(v), v < 0); (signed)
+               b.Decl(b.Var("x", nullptr, x)),
+               // let b16 = select(0, 16, bool(x & 0xffff0000));
+               b.Decl(b.Const("b16", nullptr,
+                              b.Call("select", V(0), V(16),
+                                     B(b.And("x", V(0xffff0000)))))),
+               // x = x >> b16;
+               b.Assign("x", b.Shr("x", "b16")),
+               // let b8  = select(0, 8,  bool(x & 0x0000ff00));
+               b.Decl(b.Const(
+                   "b8", nullptr,
+                   b.Call("select", V(0), V(8), B(b.And("x", V(0x0000ff00)))))),
+               // x = x >> b8;
+               b.Assign("x", b.Shr("x", "b8")),
+               // let b4  = select(0, 4,  bool(x & 0x000000f0));
+               b.Decl(b.Const(
+                   "b4", nullptr,
+                   b.Call("select", V(0), V(4), B(b.And("x", V(0x000000f0)))))),
+               // x = x >> b4;
+               b.Assign("x", b.Shr("x", "b4")),
+               // let b2  = select(0, 2,  bool(x & 0x0000000c));
+               b.Decl(b.Const(
+                   "b2", nullptr,
+                   b.Call("select", V(0), V(2), B(b.And("x", V(0x0000000c)))))),
+               // x = x >> b2;
+               b.Assign("x", b.Shr("x", "b2")),
+               // let b1  = select(0, 1,  bool(x & 0x00000002));
+               b.Decl(b.Const(
+                   "b1", nullptr,
+                   b.Call("select", V(0), V(1), B(b.And("x", V(0x00000002)))))),
+               // let is_zero  = select(0, 0xffffffff, x == 0);
+               b.Decl(b.Const("is_zero", nullptr,
+                              b.Call("select", V(0), V(0xffffffff),
+                                     b.Equal("x", V(0))))),
+               // return R(b16 | b8 | b4 | b2 | b1 | zero);
+               b.Return(b.Construct(
+                   T(ty),
+                   b.Or(b.Or(b.Or(b.Or(b.Or("b16", "b8"), "b4"), "b2"), "b1"),
+                        "is_zero"))),
+           });
+    return name;
+  }
+
   /// Builds the polyfill function for the `firstTrailingBit` builtin
   /// @param ty the parameter and return type for the function
   /// @return the polyfill function name
@@ -191,10 +266,7 @@ struct BuiltinPolyfill::State {
       return b.ty.vec<ProgramBuilder::u32>(width);
     };
     auto V = [&](uint32_t value) -> const ast::Expression* {
-      if (width == 1) {
+      return ScalarOrVector(width, value);
-        return b.Expr(value);
-      }
-      return b.Construct(b.ty.vec<ProgramBuilder::u32>(width), value);
     };
     auto B = [&](const ast::Expression* value) -> const ast::Expression* {
       if (width == 1) {
@@ -257,6 +329,13 @@ struct BuiltinPolyfill::State {
     }
     return 1;
   }
+  template <typename T>
+  const ast::Expression* ScalarOrVector(uint32_t width, T value) const {
+    if (width == 1) {
+      return b.Expr(value);
+    }
+    return b.Construct(b.ty.vec<T>(width), value);
+  }
 };
 
 BuiltinPolyfill::BuiltinPolyfill() = default;
@@ -282,6 +361,11 @@ bool BuiltinPolyfill::ShouldRun(const Program* program,
                 return true;
               }
               break;
+            case sem::BuiltinType::kFirstLeadingBit:
+              if (builtins.first_leading_bit) {
+                return true;
+              }
+              break;
             case sem::BuiltinType::kFirstTrailingBit:
               if (builtins.first_trailing_bit) {
                 return true;
@@ -330,6 +414,13 @@ void BuiltinPolyfill::Run(CloneContext& ctx,
                   });
                 }
                 break;
+              case sem::BuiltinType::kFirstLeadingBit:
+                if (builtins.first_leading_bit) {
+                  polyfill = utils::GetOrCreate(polyfills, builtin, [&] {
+                    return s.firstLeadingBit(builtin->ReturnType());
+                  });
+                }
+                break;
               case sem::BuiltinType::kFirstTrailingBit:
                 if (builtins.first_trailing_bit) {
                   polyfill = utils::GetOrCreate(polyfills, builtin, [&] {

src/tint/transform/builtin_polyfill.h

@@ -34,6 +34,8 @@ class BuiltinPolyfill : public Castable<BuiltinPolyfill, Transform> {
     bool count_leading_zeros = false;
     /// Should `countTrailingZeros()` be polyfilled?
     bool count_trailing_zeros = false;
+    /// Should `firstLeadingBit()` be polyfilled?
+    bool first_leading_bit = false;
     /// Should `firstTrailingBit()` be polyfilled?
     bool first_trailing_bit = false;
   };

src/tint/transform/builtin_polyfill_test.cc

@@ -348,6 +348,160 @@ fn f() {
   EXPECT_EQ(expect, str(got));
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// firstLeadingBit
+////////////////////////////////////////////////////////////////////////////////
+DataMap polyfillFirstLeadingBit() {
+  BuiltinPolyfill::Builtins builtins;
+  builtins.first_leading_bit = true;
+  DataMap data;
+  data.Add<BuiltinPolyfill::Config>(builtins);
+  return data;
+}
+
+TEST_F(BuiltinPolyfillTest, ShouldRunFirstLeadingBit) {
+  auto* src = R"(
+fn f() {
+  firstLeadingBit(0xf);
+}
+)";
+
+  EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src));
+  EXPECT_TRUE(ShouldRun<BuiltinPolyfill>(src, polyfillFirstLeadingBit()));
+}
+
+TEST_F(BuiltinPolyfillTest, FirstLeadingBit_i32) {
+  auto* src = R"(
+fn f() {
+  let r : i32 = firstLeadingBit(15);
+}
+)";
+
+  auto* expect = R"(
+fn tint_first_leading_bit(v : i32) -> i32 {
+  var x = select(u32(v), u32(~(v)), (v < 0));
+  let b16 = select(0u, 16u, bool((x & 4294901760u)));
+  x = (x >> b16);
+  let b8 = select(0u, 8u, bool((x & 65280u)));
+  x = (x >> b8);
+  let b4 = select(0u, 4u, bool((x & 240u)));
+  x = (x >> b4);
+  let b2 = select(0u, 2u, bool((x & 12u)));
+  x = (x >> b2);
+  let b1 = select(0u, 1u, bool((x & 2u)));
+  let is_zero = select(0u, 4294967295u, (x == 0u));
+  return i32((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+fn f() {
+  let r : i32 = tint_first_leading_bit(15);
+}
+)";
+
+  auto got = Run<BuiltinPolyfill>(src, polyfillFirstLeadingBit());
+
+  EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(BuiltinPolyfillTest, FirstLeadingBit_u32) {
+  auto* src = R"(
+fn f() {
+  let r : u32 = firstLeadingBit(15u);
+}
+)";
+
+  auto* expect = R"(
+fn tint_first_leading_bit(v : u32) -> u32 {
+  var x = v;
+  let b16 = select(0u, 16u, bool((x & 4294901760u)));
+  x = (x >> b16);
+  let b8 = select(0u, 8u, bool((x & 65280u)));
+  x = (x >> b8);
+  let b4 = select(0u, 4u, bool((x & 240u)));
+  x = (x >> b4);
+  let b2 = select(0u, 2u, bool((x & 12u)));
+  x = (x >> b2);
+  let b1 = select(0u, 1u, bool((x & 2u)));
+  let is_zero = select(0u, 4294967295u, (x == 0u));
+  return u32((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+fn f() {
+  let r : u32 = tint_first_leading_bit(15u);
+}
+)";
+
+  auto got = Run<BuiltinPolyfill>(src, polyfillFirstLeadingBit());
+
+  EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(BuiltinPolyfillTest, FirstLeadingBit_vec3_i32) {
+  auto* src = R"(
+fn f() {
+  let r : vec3<i32> = firstLeadingBit(vec3<i32>(15));
+}
+)";
+
+  auto* expect = R"(
+fn tint_first_leading_bit(v : vec3<i32>) -> vec3<i32> {
+  var x = select(vec3<u32>(v), vec3<u32>(~(v)), (v < vec3<i32>(0)));
+  let b16 = select(vec3<u32>(0u), vec3<u32>(16u), vec3<bool>((x & vec3<u32>(4294901760u))));
+  x = (x >> b16);
+  let b8 = select(vec3<u32>(0u), vec3<u32>(8u), vec3<bool>((x & vec3<u32>(65280u))));
+  x = (x >> b8);
+  let b4 = select(vec3<u32>(0u), vec3<u32>(4u), vec3<bool>((x & vec3<u32>(240u))));
+  x = (x >> b4);
+  let b2 = select(vec3<u32>(0u), vec3<u32>(2u), vec3<bool>((x & vec3<u32>(12u))));
+  x = (x >> b2);
+  let b1 = select(vec3<u32>(0u), vec3<u32>(1u), vec3<bool>((x & vec3<u32>(2u))));
+  let is_zero = select(vec3<u32>(0u), vec3<u32>(4294967295u), (x == vec3<u32>(0u)));
+  return vec3<i32>((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+fn f() {
+  let r : vec3<i32> = tint_first_leading_bit(vec3<i32>(15));
+}
+)";
+
+  auto got = Run<BuiltinPolyfill>(src, polyfillFirstLeadingBit());
+
+  EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(BuiltinPolyfillTest, FirstLeadingBit_vec3_u32) {
+  auto* src = R"(
+fn f() {
+  let r : vec3<u32> = firstLeadingBit(vec3<u32>(15u));
+}
+)";
+
+  auto* expect = R"(
+fn tint_first_leading_bit(v : vec3<u32>) -> vec3<u32> {
+  var x = v;
+  let b16 = select(vec3<u32>(0u), vec3<u32>(16u), vec3<bool>((x & vec3<u32>(4294901760u))));
+  x = (x >> b16);
+  let b8 = select(vec3<u32>(0u), vec3<u32>(8u), vec3<bool>((x & vec3<u32>(65280u))));
+  x = (x >> b8);
+  let b4 = select(vec3<u32>(0u), vec3<u32>(4u), vec3<bool>((x & vec3<u32>(240u))));
+  x = (x >> b4);
+  let b2 = select(vec3<u32>(0u), vec3<u32>(2u), vec3<bool>((x & vec3<u32>(12u))));
+  x = (x >> b2);
+  let b1 = select(vec3<u32>(0u), vec3<u32>(1u), vec3<bool>((x & vec3<u32>(2u))));
+  let is_zero = select(vec3<u32>(0u), vec3<u32>(4294967295u), (x == vec3<u32>(0u)));
+  return vec3<u32>((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+fn f() {
+  let r : vec3<u32> = tint_first_leading_bit(vec3<u32>(15u));
+}
+)";
+
+  auto got = Run<BuiltinPolyfill>(src, polyfillFirstLeadingBit());
+
+  EXPECT_EQ(expect, str(got));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // firstTrailingBit
 ////////////////////////////////////////////////////////////////////////////////

src/tint/transform/glsl.cc

@@ -56,6 +56,7 @@ Output Glsl::Run(const Program* in, const DataMap& inputs) const {
     BuiltinPolyfill::Builtins polyfills;
     polyfills.count_leading_zeros = true;
     polyfills.count_trailing_zeros = true;
+    polyfills.first_leading_bit = true;
     polyfills.first_trailing_bit = true;
     data.Add<BuiltinPolyfill::Config>(polyfills);
     manager.Add<BuiltinPolyfill>();

src/tint/writer/hlsl/generator_impl.cc

@@ -147,6 +147,7 @@ SanitizedResult Sanitize(
     // and `firstbithigh`.
     polyfills.count_leading_zeros = true;
     polyfills.count_trailing_zeros = true;
+    polyfills.first_leading_bit = true;
     polyfills.first_trailing_bit = true;
     data.Add<transform::BuiltinPolyfill::Config>(polyfills);
     manager.Add<transform::BuiltinPolyfill>();

src/tint/writer/msl/generator_impl.cc

@@ -130,6 +130,7 @@ SanitizedResult Sanitize(
 
   {  // Builtin polyfills
     transform::BuiltinPolyfill::Builtins polyfills;
+    polyfills.first_leading_bit = true;
     polyfills.first_trailing_bit = true;
     data.Add<transform::BuiltinPolyfill::Config>(polyfills);
     manager.Add<transform::BuiltinPolyfill>();

src/tint/writer/spirv/builder.cc

@@ -263,6 +263,7 @@ SanitizedResult Sanitize(const Program* in,
     transform::BuiltinPolyfill::Builtins polyfills;
     polyfills.count_leading_zeros = true;
     polyfills.count_trailing_zeros = true;
+    polyfills.first_leading_bit = true;
     polyfills.first_trailing_bit = true;
     data.Add<transform::BuiltinPolyfill::Config>(polyfills);
     manager.Add<transform::BuiltinPolyfill>();

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<4, u32>) -> vec<4, u32>
+fn firstLeadingBit_000ff3() {
+  var res: vec4<u32> = firstLeadingBit(vec4<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_000ff3();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_000ff3();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_000ff3();
+}

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+uvec4 tint_first_leading_bit(uvec4 v) {
+  uvec4 x = v;
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return uvec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_000ff3() {
+  uvec4 res = tint_first_leading_bit(uvec4(0u, 0u, 0u, 0u));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_000ff3();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+uvec4 tint_first_leading_bit(uvec4 v) {
+  uvec4 x = v;
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return uvec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_000ff3() {
+  uvec4 res = tint_first_leading_bit(uvec4(0u, 0u, 0u, 0u));
+}
+
+void fragment_main() {
+  firstLeadingBit_000ff3();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+uvec4 tint_first_leading_bit(uvec4 v) {
+  uvec4 x = v;
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return uvec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_000ff3() {
+  uvec4 res = tint_first_leading_bit(uvec4(0u, 0u, 0u, 0u));
+}
+
+void compute_main() {
+  firstLeadingBit_000ff3();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+uint4 tint_first_leading_bit(uint4 v) {
+  uint4 x = v;
+  const uint4 b16 = (bool4((x & uint4((4294901760u).xxxx))) ? uint4((16u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b16);
+  const uint4 b8 = (bool4((x & uint4((65280u).xxxx))) ? uint4((8u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b8);
+  const uint4 b4 = (bool4((x & uint4((240u).xxxx))) ? uint4((4u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b4);
+  const uint4 b2 = (bool4((x & uint4((12u).xxxx))) ? uint4((2u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b2);
+  const uint4 b1 = (bool4((x & uint4((2u).xxxx))) ? uint4((1u).xxxx) : uint4((0u).xxxx));
+  const uint4 is_zero = ((x == uint4((0u).xxxx)) ? uint4((4294967295u).xxxx) : uint4((0u).xxxx));
+  return uint4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_000ff3() {
+  uint4 res = tint_first_leading_bit(uint4(0u, 0u, 0u, 0u));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_000ff3();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_000ff3();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_000ff3();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+uint4 tint_first_leading_bit(uint4 v) {
+  uint4 x = v;
+  uint4 const b16 = select(uint4(0u), uint4(16u), bool4((x & uint4(4294901760u))));
+  x = (x >> b16);
+  uint4 const b8 = select(uint4(0u), uint4(8u), bool4((x & uint4(65280u))));
+  x = (x >> b8);
+  uint4 const b4 = select(uint4(0u), uint4(4u), bool4((x & uint4(240u))));
+  x = (x >> b4);
+  uint4 const b2 = select(uint4(0u), uint4(2u), bool4((x & uint4(12u))));
+  x = (x >> b2);
+  uint4 const b1 = select(uint4(0u), uint4(1u), bool4((x & uint4(2u))));
+  uint4 const is_zero = select(uint4(0u), uint4(4294967295u), (x == uint4(0u)));
+  return uint4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_000ff3() {
+  uint4 res = tint_first_leading_bit(uint4());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_000ff3();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_000ff3();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_000ff3();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl.expected.spvasm

@@ -0,0 +1,142 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 99
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_000ff3 "firstLeadingBit_000ff3"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+       %uint = OpTypeInt 32 0
+     %v4uint = OpTypeVector %uint 4
+          %9 = OpTypeFunction %v4uint %v4uint
+%_ptr_Function_v4uint = OpTypePointer Function %v4uint
+         %17 = OpConstantNull %v4uint
+       %bool = OpTypeBool
+     %v4bool = OpTypeVector %bool 4
+%uint_4294901760 = OpConstant %uint 4294901760
+         %24 = OpConstantComposite %v4uint %uint_4294901760 %uint_4294901760 %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %27 = OpConstantComposite %v4uint %uint_16 %uint_16 %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %29 = OpConstantComposite %v4uint %uint_0 %uint_0 %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %36 = OpConstantComposite %v4uint %uint_65280 %uint_65280 %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %39 = OpConstantComposite %v4uint %uint_8 %uint_8 %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %46 = OpConstantComposite %v4uint %uint_240 %uint_240 %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %49 = OpConstantComposite %v4uint %uint_4 %uint_4 %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %56 = OpConstantComposite %v4uint %uint_12 %uint_12 %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %59 = OpConstantComposite %v4uint %uint_2 %uint_2 %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %67 = OpConstantComposite %v4uint %uint_1 %uint_1 %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %72 = OpConstantComposite %v4uint %uint_4294967295 %uint_4294967295 %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %79 = OpTypeFunction %void
+         %85 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v4uint None %9
+          %v = OpFunctionParameter %v4uint
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v4uint Function %17
+               OpStore %x %v
+         %22 = OpLoad %v4uint %x
+         %25 = OpBitwiseAnd %v4uint %22 %24
+         %19 = OpINotEqual %v4bool %25 %17
+         %18 = OpSelect %v4uint %19 %27 %29
+         %30 = OpLoad %v4uint %x
+         %31 = OpShiftRightLogical %v4uint %30 %18
+               OpStore %x %31
+         %34 = OpLoad %v4uint %x
+         %37 = OpBitwiseAnd %v4uint %34 %36
+         %33 = OpINotEqual %v4bool %37 %17
+         %32 = OpSelect %v4uint %33 %39 %29
+         %40 = OpLoad %v4uint %x
+         %41 = OpShiftRightLogical %v4uint %40 %32
+               OpStore %x %41
+         %44 = OpLoad %v4uint %x
+         %47 = OpBitwiseAnd %v4uint %44 %46
+         %43 = OpINotEqual %v4bool %47 %17
+         %42 = OpSelect %v4uint %43 %49 %29
+         %50 = OpLoad %v4uint %x
+         %51 = OpShiftRightLogical %v4uint %50 %42
+               OpStore %x %51
+         %54 = OpLoad %v4uint %x
+         %57 = OpBitwiseAnd %v4uint %54 %56
+         %53 = OpINotEqual %v4bool %57 %17
+         %52 = OpSelect %v4uint %53 %59 %29
+         %60 = OpLoad %v4uint %x
+         %61 = OpShiftRightLogical %v4uint %60 %52
+               OpStore %x %61
+         %64 = OpLoad %v4uint %x
+         %65 = OpBitwiseAnd %v4uint %64 %59
+         %63 = OpINotEqual %v4bool %65 %17
+         %62 = OpSelect %v4uint %63 %67 %29
+         %69 = OpLoad %v4uint %x
+         %70 = OpIEqual %v4bool %69 %29
+         %68 = OpSelect %v4uint %70 %72 %29
+         %74 = OpBitwiseOr %v4uint %18 %32
+         %75 = OpBitwiseOr %v4uint %74 %42
+         %76 = OpBitwiseOr %v4uint %75 %52
+         %77 = OpBitwiseOr %v4uint %76 %62
+         %78 = OpBitwiseOr %v4uint %77 %68
+               OpReturnValue %78
+               OpFunctionEnd
+%firstLeadingBit_000ff3 = OpFunction %void None %79
+         %82 = OpLabel
+        %res = OpVariable %_ptr_Function_v4uint Function %17
+         %83 = OpFunctionCall %v4uint %tint_first_leading_bit %17
+               OpStore %res %83
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %85
+         %87 = OpLabel
+         %88 = OpFunctionCall %void %firstLeadingBit_000ff3
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %79
+         %90 = OpLabel
+         %91 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %91
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %79
+         %94 = OpLabel
+         %95 = OpFunctionCall %void %firstLeadingBit_000ff3
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %79
+         %97 = OpLabel
+         %98 = OpFunctionCall %void %firstLeadingBit_000ff3
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/000ff3.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_000ff3() {
+  var res : vec4<u32> = firstLeadingBit(vec4<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_000ff3();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_000ff3();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_000ff3();
+}

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<3, i32>) -> vec<3, i32>
+fn firstLeadingBit_35053e() {
+  var res: vec3<i32> = firstLeadingBit(vec3<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_35053e();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_35053e();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_35053e();
+}

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+ivec3 tint_first_leading_bit(ivec3 v) {
+  uvec3 x = mix(uvec3(v), uvec3(~(v)), lessThan(v, ivec3(0)));
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return ivec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_35053e() {
+  ivec3 res = tint_first_leading_bit(ivec3(0, 0, 0));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_35053e();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+ivec3 tint_first_leading_bit(ivec3 v) {
+  uvec3 x = mix(uvec3(v), uvec3(~(v)), lessThan(v, ivec3(0)));
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return ivec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_35053e() {
+  ivec3 res = tint_first_leading_bit(ivec3(0, 0, 0));
+}
+
+void fragment_main() {
+  firstLeadingBit_35053e();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+ivec3 tint_first_leading_bit(ivec3 v) {
+  uvec3 x = mix(uvec3(v), uvec3(~(v)), lessThan(v, ivec3(0)));
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return ivec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_35053e() {
+  ivec3 res = tint_first_leading_bit(ivec3(0, 0, 0));
+}
+
+void compute_main() {
+  firstLeadingBit_35053e();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+int3 tint_first_leading_bit(int3 v) {
+  uint3 x = ((v < int3((0).xxx)) ? uint3(~(v)) : uint3(v));
+  const uint3 b16 = (bool3((x & uint3((4294901760u).xxx))) ? uint3((16u).xxx) : uint3((0u).xxx));
+  x = (x >> b16);
+  const uint3 b8 = (bool3((x & uint3((65280u).xxx))) ? uint3((8u).xxx) : uint3((0u).xxx));
+  x = (x >> b8);
+  const uint3 b4 = (bool3((x & uint3((240u).xxx))) ? uint3((4u).xxx) : uint3((0u).xxx));
+  x = (x >> b4);
+  const uint3 b2 = (bool3((x & uint3((12u).xxx))) ? uint3((2u).xxx) : uint3((0u).xxx));
+  x = (x >> b2);
+  const uint3 b1 = (bool3((x & uint3((2u).xxx))) ? uint3((1u).xxx) : uint3((0u).xxx));
+  const uint3 is_zero = ((x == uint3((0u).xxx)) ? uint3((4294967295u).xxx) : uint3((0u).xxx));
+  return int3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_35053e() {
+  int3 res = tint_first_leading_bit(int3(0, 0, 0));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_35053e();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_35053e();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_35053e();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+int3 tint_first_leading_bit(int3 v) {
+  uint3 x = select(uint3(v), uint3(~(v)), (v < int3(0)));
+  uint3 const b16 = select(uint3(0u), uint3(16u), bool3((x & uint3(4294901760u))));
+  x = (x >> b16);
+  uint3 const b8 = select(uint3(0u), uint3(8u), bool3((x & uint3(65280u))));
+  x = (x >> b8);
+  uint3 const b4 = select(uint3(0u), uint3(4u), bool3((x & uint3(240u))));
+  x = (x >> b4);
+  uint3 const b2 = select(uint3(0u), uint3(2u), bool3((x & uint3(12u))));
+  x = (x >> b2);
+  uint3 const b1 = select(uint3(0u), uint3(1u), bool3((x & uint3(2u))));
+  uint3 const is_zero = select(uint3(0u), uint3(4294967295u), (x == uint3(0u)));
+  return int3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_35053e() {
+  int3 res = tint_first_leading_bit(int3());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_35053e();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_35053e();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_35053e();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl.expected.spvasm

@@ -0,0 +1,154 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 110
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_35053e "firstLeadingBit_35053e"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+        %int = OpTypeInt 32 1
+      %v3int = OpTypeVector %int 3
+          %9 = OpTypeFunction %v3int %v3int
+       %uint = OpTypeInt 32 0
+     %v3uint = OpTypeVector %uint 3
+      %int_0 = OpConstant %int 0
+         %19 = OpConstantComposite %v3int %int_0 %int_0 %int_0
+       %bool = OpTypeBool
+     %v3bool = OpTypeVector %bool 3
+%_ptr_Function_v3uint = OpTypePointer Function %v3uint
+         %28 = OpConstantNull %v3uint
+%uint_4294901760 = OpConstant %uint 4294901760
+         %33 = OpConstantComposite %v3uint %uint_4294901760 %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %36 = OpConstantComposite %v3uint %uint_16 %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %38 = OpConstantComposite %v3uint %uint_0 %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %45 = OpConstantComposite %v3uint %uint_65280 %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %48 = OpConstantComposite %v3uint %uint_8 %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %55 = OpConstantComposite %v3uint %uint_240 %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %58 = OpConstantComposite %v3uint %uint_4 %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %65 = OpConstantComposite %v3uint %uint_12 %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %68 = OpConstantComposite %v3uint %uint_2 %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %76 = OpConstantComposite %v3uint %uint_1 %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %81 = OpConstantComposite %v3uint %uint_4294967295 %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %88 = OpTypeFunction %void
+         %93 = OpConstantNull %v3int
+%_ptr_Function_v3int = OpTypePointer Function %v3int
+         %96 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v3int None %9
+          %v = OpFunctionParameter %v3int
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v3uint Function %28
+         %20 = OpSLessThan %v3bool %v %19
+         %24 = OpNot %v3int %v
+         %23 = OpBitcast %v3uint %24
+         %25 = OpBitcast %v3uint %v
+         %15 = OpSelect %v3uint %20 %23 %25
+               OpStore %x %15
+         %31 = OpLoad %v3uint %x
+         %34 = OpBitwiseAnd %v3uint %31 %33
+         %30 = OpINotEqual %v3bool %34 %28
+         %29 = OpSelect %v3uint %30 %36 %38
+         %39 = OpLoad %v3uint %x
+         %40 = OpShiftRightLogical %v3uint %39 %29
+               OpStore %x %40
+         %43 = OpLoad %v3uint %x
+         %46 = OpBitwiseAnd %v3uint %43 %45
+         %42 = OpINotEqual %v3bool %46 %28
+         %41 = OpSelect %v3uint %42 %48 %38
+         %49 = OpLoad %v3uint %x
+         %50 = OpShiftRightLogical %v3uint %49 %41
+               OpStore %x %50
+         %53 = OpLoad %v3uint %x
+         %56 = OpBitwiseAnd %v3uint %53 %55
+         %52 = OpINotEqual %v3bool %56 %28
+         %51 = OpSelect %v3uint %52 %58 %38
+         %59 = OpLoad %v3uint %x
+         %60 = OpShiftRightLogical %v3uint %59 %51
+               OpStore %x %60
+         %63 = OpLoad %v3uint %x
+         %66 = OpBitwiseAnd %v3uint %63 %65
+         %62 = OpINotEqual %v3bool %66 %28
+         %61 = OpSelect %v3uint %62 %68 %38
+         %69 = OpLoad %v3uint %x
+         %70 = OpShiftRightLogical %v3uint %69 %61
+               OpStore %x %70
+         %73 = OpLoad %v3uint %x
+         %74 = OpBitwiseAnd %v3uint %73 %68
+         %72 = OpINotEqual %v3bool %74 %28
+         %71 = OpSelect %v3uint %72 %76 %38
+         %78 = OpLoad %v3uint %x
+         %79 = OpIEqual %v3bool %78 %38
+         %77 = OpSelect %v3uint %79 %81 %38
+         %83 = OpBitwiseOr %v3uint %29 %41
+         %84 = OpBitwiseOr %v3uint %83 %51
+         %85 = OpBitwiseOr %v3uint %84 %61
+         %86 = OpBitwiseOr %v3uint %85 %71
+         %87 = OpBitwiseOr %v3uint %86 %77
+         %82 = OpBitcast %v3int %87
+               OpReturnValue %82
+               OpFunctionEnd
+%firstLeadingBit_35053e = OpFunction %void None %88
+         %91 = OpLabel
+        %res = OpVariable %_ptr_Function_v3int Function %93
+         %92 = OpFunctionCall %v3int %tint_first_leading_bit %93
+               OpStore %res %92
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %96
+         %98 = OpLabel
+         %99 = OpFunctionCall %void %firstLeadingBit_35053e
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %88
+        %101 = OpLabel
+        %102 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %102
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %88
+        %105 = OpLabel
+        %106 = OpFunctionCall %void %firstLeadingBit_35053e
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %88
+        %108 = OpLabel
+        %109 = OpFunctionCall %void %firstLeadingBit_35053e
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/35053e.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_35053e() {
+  var res : vec3<i32> = firstLeadingBit(vec3<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_35053e();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_35053e();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_35053e();
+}

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<3, u32>) -> vec<3, u32>
+fn firstLeadingBit_3fd7d0() {
+  var res: vec3<u32> = firstLeadingBit(vec3<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_3fd7d0();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_3fd7d0();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_3fd7d0();
+}

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+uvec3 tint_first_leading_bit(uvec3 v) {
+  uvec3 x = v;
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return uvec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_3fd7d0() {
+  uvec3 res = tint_first_leading_bit(uvec3(0u, 0u, 0u));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_3fd7d0();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+uvec3 tint_first_leading_bit(uvec3 v) {
+  uvec3 x = v;
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return uvec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_3fd7d0() {
+  uvec3 res = tint_first_leading_bit(uvec3(0u, 0u, 0u));
+}
+
+void fragment_main() {
+  firstLeadingBit_3fd7d0();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+uvec3 tint_first_leading_bit(uvec3 v) {
+  uvec3 x = v;
+  uvec3 b16 = mix(uvec3(0u), uvec3(16u), bvec3((x & uvec3(4294901760u))));
+  x = (x >> b16);
+  uvec3 b8 = mix(uvec3(0u), uvec3(8u), bvec3((x & uvec3(65280u))));
+  x = (x >> b8);
+  uvec3 b4 = mix(uvec3(0u), uvec3(4u), bvec3((x & uvec3(240u))));
+  x = (x >> b4);
+  uvec3 b2 = mix(uvec3(0u), uvec3(2u), bvec3((x & uvec3(12u))));
+  x = (x >> b2);
+  uvec3 b1 = mix(uvec3(0u), uvec3(1u), bvec3((x & uvec3(2u))));
+  uvec3 is_zero = mix(uvec3(0u), uvec3(4294967295u), equal(x, uvec3(0u)));
+  return uvec3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_3fd7d0() {
+  uvec3 res = tint_first_leading_bit(uvec3(0u, 0u, 0u));
+}
+
+void compute_main() {
+  firstLeadingBit_3fd7d0();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+uint3 tint_first_leading_bit(uint3 v) {
+  uint3 x = v;
+  const uint3 b16 = (bool3((x & uint3((4294901760u).xxx))) ? uint3((16u).xxx) : uint3((0u).xxx));
+  x = (x >> b16);
+  const uint3 b8 = (bool3((x & uint3((65280u).xxx))) ? uint3((8u).xxx) : uint3((0u).xxx));
+  x = (x >> b8);
+  const uint3 b4 = (bool3((x & uint3((240u).xxx))) ? uint3((4u).xxx) : uint3((0u).xxx));
+  x = (x >> b4);
+  const uint3 b2 = (bool3((x & uint3((12u).xxx))) ? uint3((2u).xxx) : uint3((0u).xxx));
+  x = (x >> b2);
+  const uint3 b1 = (bool3((x & uint3((2u).xxx))) ? uint3((1u).xxx) : uint3((0u).xxx));
+  const uint3 is_zero = ((x == uint3((0u).xxx)) ? uint3((4294967295u).xxx) : uint3((0u).xxx));
+  return uint3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_3fd7d0() {
+  uint3 res = tint_first_leading_bit(uint3(0u, 0u, 0u));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_3fd7d0();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_3fd7d0();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_3fd7d0();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+uint3 tint_first_leading_bit(uint3 v) {
+  uint3 x = v;
+  uint3 const b16 = select(uint3(0u), uint3(16u), bool3((x & uint3(4294901760u))));
+  x = (x >> b16);
+  uint3 const b8 = select(uint3(0u), uint3(8u), bool3((x & uint3(65280u))));
+  x = (x >> b8);
+  uint3 const b4 = select(uint3(0u), uint3(4u), bool3((x & uint3(240u))));
+  x = (x >> b4);
+  uint3 const b2 = select(uint3(0u), uint3(2u), bool3((x & uint3(12u))));
+  x = (x >> b2);
+  uint3 const b1 = select(uint3(0u), uint3(1u), bool3((x & uint3(2u))));
+  uint3 const is_zero = select(uint3(0u), uint3(4294967295u), (x == uint3(0u)));
+  return uint3((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_3fd7d0() {
+  uint3 res = tint_first_leading_bit(uint3());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_3fd7d0();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_3fd7d0();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_3fd7d0();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl.expected.spvasm

@@ -0,0 +1,142 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 99
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_3fd7d0 "firstLeadingBit_3fd7d0"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+       %uint = OpTypeInt 32 0
+     %v3uint = OpTypeVector %uint 3
+          %9 = OpTypeFunction %v3uint %v3uint
+%_ptr_Function_v3uint = OpTypePointer Function %v3uint
+         %17 = OpConstantNull %v3uint
+       %bool = OpTypeBool
+     %v3bool = OpTypeVector %bool 3
+%uint_4294901760 = OpConstant %uint 4294901760
+         %24 = OpConstantComposite %v3uint %uint_4294901760 %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %27 = OpConstantComposite %v3uint %uint_16 %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %29 = OpConstantComposite %v3uint %uint_0 %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %36 = OpConstantComposite %v3uint %uint_65280 %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %39 = OpConstantComposite %v3uint %uint_8 %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %46 = OpConstantComposite %v3uint %uint_240 %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %49 = OpConstantComposite %v3uint %uint_4 %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %56 = OpConstantComposite %v3uint %uint_12 %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %59 = OpConstantComposite %v3uint %uint_2 %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %67 = OpConstantComposite %v3uint %uint_1 %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %72 = OpConstantComposite %v3uint %uint_4294967295 %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %79 = OpTypeFunction %void
+         %85 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v3uint None %9
+          %v = OpFunctionParameter %v3uint
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v3uint Function %17
+               OpStore %x %v
+         %22 = OpLoad %v3uint %x
+         %25 = OpBitwiseAnd %v3uint %22 %24
+         %19 = OpINotEqual %v3bool %25 %17
+         %18 = OpSelect %v3uint %19 %27 %29
+         %30 = OpLoad %v3uint %x
+         %31 = OpShiftRightLogical %v3uint %30 %18
+               OpStore %x %31
+         %34 = OpLoad %v3uint %x
+         %37 = OpBitwiseAnd %v3uint %34 %36
+         %33 = OpINotEqual %v3bool %37 %17
+         %32 = OpSelect %v3uint %33 %39 %29
+         %40 = OpLoad %v3uint %x
+         %41 = OpShiftRightLogical %v3uint %40 %32
+               OpStore %x %41
+         %44 = OpLoad %v3uint %x
+         %47 = OpBitwiseAnd %v3uint %44 %46
+         %43 = OpINotEqual %v3bool %47 %17
+         %42 = OpSelect %v3uint %43 %49 %29
+         %50 = OpLoad %v3uint %x
+         %51 = OpShiftRightLogical %v3uint %50 %42
+               OpStore %x %51
+         %54 = OpLoad %v3uint %x
+         %57 = OpBitwiseAnd %v3uint %54 %56
+         %53 = OpINotEqual %v3bool %57 %17
+         %52 = OpSelect %v3uint %53 %59 %29
+         %60 = OpLoad %v3uint %x
+         %61 = OpShiftRightLogical %v3uint %60 %52
+               OpStore %x %61
+         %64 = OpLoad %v3uint %x
+         %65 = OpBitwiseAnd %v3uint %64 %59
+         %63 = OpINotEqual %v3bool %65 %17
+         %62 = OpSelect %v3uint %63 %67 %29
+         %69 = OpLoad %v3uint %x
+         %70 = OpIEqual %v3bool %69 %29
+         %68 = OpSelect %v3uint %70 %72 %29
+         %74 = OpBitwiseOr %v3uint %18 %32
+         %75 = OpBitwiseOr %v3uint %74 %42
+         %76 = OpBitwiseOr %v3uint %75 %52
+         %77 = OpBitwiseOr %v3uint %76 %62
+         %78 = OpBitwiseOr %v3uint %77 %68
+               OpReturnValue %78
+               OpFunctionEnd
+%firstLeadingBit_3fd7d0 = OpFunction %void None %79
+         %82 = OpLabel
+        %res = OpVariable %_ptr_Function_v3uint Function %17
+         %83 = OpFunctionCall %v3uint %tint_first_leading_bit %17
+               OpStore %res %83
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %85
+         %87 = OpLabel
+         %88 = OpFunctionCall %void %firstLeadingBit_3fd7d0
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %79
+         %90 = OpLabel
+         %91 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %91
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %79
+         %94 = OpLabel
+         %95 = OpFunctionCall %void %firstLeadingBit_3fd7d0
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %79
+         %97 = OpLabel
+         %98 = OpFunctionCall %void %firstLeadingBit_3fd7d0
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/3fd7d0.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_3fd7d0() {
+  var res : vec3<u32> = firstLeadingBit(vec3<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_3fd7d0();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_3fd7d0();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_3fd7d0();
+}

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(i32) -> i32
+fn firstLeadingBit_57a1a3() {
+  var res: i32 = firstLeadingBit(1);
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_57a1a3();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_57a1a3();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_57a1a3();
+}

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+int tint_first_leading_bit(int v) {
+  uint x = ((v < 0) ? uint(~(v)) : uint(v));
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return int((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_57a1a3() {
+  int res = tint_first_leading_bit(1);
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_57a1a3();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+int tint_first_leading_bit(int v) {
+  uint x = ((v < 0) ? uint(~(v)) : uint(v));
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return int((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_57a1a3() {
+  int res = tint_first_leading_bit(1);
+}
+
+void fragment_main() {
+  firstLeadingBit_57a1a3();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+int tint_first_leading_bit(int v) {
+  uint x = ((v < 0) ? uint(~(v)) : uint(v));
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return int((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_57a1a3() {
+  int res = tint_first_leading_bit(1);
+}
+
+void compute_main() {
+  firstLeadingBit_57a1a3();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+int tint_first_leading_bit(int v) {
+  uint x = ((v < 0) ? uint(~(v)) : uint(v));
+  const uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  const uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  const uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  const uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  const uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  const uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return int((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_57a1a3() {
+  int res = tint_first_leading_bit(1);
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_57a1a3();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_57a1a3();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_57a1a3();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+int tint_first_leading_bit(int v) {
+  uint x = select(uint(v), uint(~(v)), (v < 0));
+  uint const b16 = select(0u, 16u, bool((x & 4294901760u)));
+  x = (x >> b16);
+  uint const b8 = select(0u, 8u, bool((x & 65280u)));
+  x = (x >> b8);
+  uint const b4 = select(0u, 4u, bool((x & 240u)));
+  x = (x >> b4);
+  uint const b2 = select(0u, 2u, bool((x & 12u)));
+  x = (x >> b2);
+  uint const b1 = select(0u, 1u, bool((x & 2u)));
+  uint const is_zero = select(0u, 4294967295u, (x == 0u));
+  return int((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_57a1a3() {
+  int res = tint_first_leading_bit(1);
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_57a1a3();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_57a1a3();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_57a1a3();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl.expected.spvasm

@@ -0,0 +1,140 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 96
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_57a1a3 "firstLeadingBit_57a1a3"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+        %int = OpTypeInt 32 1
+          %9 = OpTypeFunction %int %int
+       %uint = OpTypeInt 32 0
+      %int_0 = OpConstant %int 0
+       %bool = OpTypeBool
+%_ptr_Function_uint = OpTypePointer Function %uint
+         %24 = OpConstantNull %uint
+%uint_4294901760 = OpConstant %uint 4294901760
+    %uint_16 = OpConstant %uint 16
+     %uint_0 = OpConstant %uint 0
+ %uint_65280 = OpConstant %uint 65280
+     %uint_8 = OpConstant %uint 8
+   %uint_240 = OpConstant %uint 240
+     %uint_4 = OpConstant %uint 4
+    %uint_12 = OpConstant %uint 12
+     %uint_2 = OpConstant %uint 2
+     %uint_1 = OpConstant %uint 1
+%uint_4294967295 = OpConstant %uint 4294967295
+       %void = OpTypeVoid
+         %73 = OpTypeFunction %void
+      %int_1 = OpConstant %int 1
+%_ptr_Function_int = OpTypePointer Function %int
+         %81 = OpConstantNull %int
+         %82 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %int None %9
+          %v = OpFunctionParameter %int
+         %13 = OpLabel
+          %x = OpVariable %_ptr_Function_uint Function %24
+         %17 = OpSLessThan %bool %v %int_0
+         %20 = OpNot %int %v
+         %19 = OpBitcast %uint %20
+         %21 = OpBitcast %uint %v
+         %14 = OpSelect %uint %17 %19 %21
+               OpStore %x %14
+         %27 = OpLoad %uint %x
+         %29 = OpBitwiseAnd %uint %27 %uint_4294901760
+         %26 = OpINotEqual %bool %29 %24
+         %25 = OpSelect %uint %26 %uint_16 %uint_0
+         %32 = OpLoad %uint %x
+         %33 = OpShiftRightLogical %uint %32 %25
+               OpStore %x %33
+         %36 = OpLoad %uint %x
+         %38 = OpBitwiseAnd %uint %36 %uint_65280
+         %35 = OpINotEqual %bool %38 %24
+         %34 = OpSelect %uint %35 %uint_8 %uint_0
+         %40 = OpLoad %uint %x
+         %41 = OpShiftRightLogical %uint %40 %34
+               OpStore %x %41
+         %44 = OpLoad %uint %x
+         %46 = OpBitwiseAnd %uint %44 %uint_240
+         %43 = OpINotEqual %bool %46 %24
+         %42 = OpSelect %uint %43 %uint_4 %uint_0
+         %48 = OpLoad %uint %x
+         %49 = OpShiftRightLogical %uint %48 %42
+               OpStore %x %49
+         %52 = OpLoad %uint %x
+         %54 = OpBitwiseAnd %uint %52 %uint_12
+         %51 = OpINotEqual %bool %54 %24
+         %50 = OpSelect %uint %51 %uint_2 %uint_0
+         %56 = OpLoad %uint %x
+         %57 = OpShiftRightLogical %uint %56 %50
+               OpStore %x %57
+         %60 = OpLoad %uint %x
+         %61 = OpBitwiseAnd %uint %60 %uint_2
+         %59 = OpINotEqual %bool %61 %24
+         %58 = OpSelect %uint %59 %uint_1 %uint_0
+         %64 = OpLoad %uint %x
+         %65 = OpIEqual %bool %64 %uint_0
+         %63 = OpSelect %uint %65 %uint_4294967295 %uint_0
+         %68 = OpBitwiseOr %uint %25 %34
+         %69 = OpBitwiseOr %uint %68 %42
+         %70 = OpBitwiseOr %uint %69 %50
+         %71 = OpBitwiseOr %uint %70 %58
+         %72 = OpBitwiseOr %uint %71 %63
+         %67 = OpBitcast %int %72
+               OpReturnValue %67
+               OpFunctionEnd
+%firstLeadingBit_57a1a3 = OpFunction %void None %73
+         %76 = OpLabel
+        %res = OpVariable %_ptr_Function_int Function %81
+         %77 = OpFunctionCall %int %tint_first_leading_bit %int_1
+               OpStore %res %77
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %82
+         %84 = OpLabel
+         %85 = OpFunctionCall %void %firstLeadingBit_57a1a3
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %73
+         %87 = OpLabel
+         %88 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %88
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %73
+         %91 = OpLabel
+         %92 = OpFunctionCall %void %firstLeadingBit_57a1a3
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %73
+         %94 = OpLabel
+         %95 = OpFunctionCall %void %firstLeadingBit_57a1a3
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/57a1a3.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_57a1a3() {
+  var res : i32 = firstLeadingBit(1);
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_57a1a3();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_57a1a3();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_57a1a3();
+}

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<2, u32>) -> vec<2, u32>
+fn firstLeadingBit_6fe804() {
+  var res: vec2<u32> = firstLeadingBit(vec2<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_6fe804();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_6fe804();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_6fe804();
+}

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+uvec2 tint_first_leading_bit(uvec2 v) {
+  uvec2 x = v;
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return uvec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_6fe804() {
+  uvec2 res = tint_first_leading_bit(uvec2(0u, 0u));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_6fe804();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+uvec2 tint_first_leading_bit(uvec2 v) {
+  uvec2 x = v;
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return uvec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_6fe804() {
+  uvec2 res = tint_first_leading_bit(uvec2(0u, 0u));
+}
+
+void fragment_main() {
+  firstLeadingBit_6fe804();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+uvec2 tint_first_leading_bit(uvec2 v) {
+  uvec2 x = v;
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return uvec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_6fe804() {
+  uvec2 res = tint_first_leading_bit(uvec2(0u, 0u));
+}
+
+void compute_main() {
+  firstLeadingBit_6fe804();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+uint2 tint_first_leading_bit(uint2 v) {
+  uint2 x = v;
+  const uint2 b16 = (bool2((x & uint2((4294901760u).xx))) ? uint2((16u).xx) : uint2((0u).xx));
+  x = (x >> b16);
+  const uint2 b8 = (bool2((x & uint2((65280u).xx))) ? uint2((8u).xx) : uint2((0u).xx));
+  x = (x >> b8);
+  const uint2 b4 = (bool2((x & uint2((240u).xx))) ? uint2((4u).xx) : uint2((0u).xx));
+  x = (x >> b4);
+  const uint2 b2 = (bool2((x & uint2((12u).xx))) ? uint2((2u).xx) : uint2((0u).xx));
+  x = (x >> b2);
+  const uint2 b1 = (bool2((x & uint2((2u).xx))) ? uint2((1u).xx) : uint2((0u).xx));
+  const uint2 is_zero = ((x == uint2((0u).xx)) ? uint2((4294967295u).xx) : uint2((0u).xx));
+  return uint2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_6fe804() {
+  uint2 res = tint_first_leading_bit(uint2(0u, 0u));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_6fe804();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_6fe804();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_6fe804();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+uint2 tint_first_leading_bit(uint2 v) {
+  uint2 x = v;
+  uint2 const b16 = select(uint2(0u), uint2(16u), bool2((x & uint2(4294901760u))));
+  x = (x >> b16);
+  uint2 const b8 = select(uint2(0u), uint2(8u), bool2((x & uint2(65280u))));
+  x = (x >> b8);
+  uint2 const b4 = select(uint2(0u), uint2(4u), bool2((x & uint2(240u))));
+  x = (x >> b4);
+  uint2 const b2 = select(uint2(0u), uint2(2u), bool2((x & uint2(12u))));
+  x = (x >> b2);
+  uint2 const b1 = select(uint2(0u), uint2(1u), bool2((x & uint2(2u))));
+  uint2 const is_zero = select(uint2(0u), uint2(4294967295u), (x == uint2(0u)));
+  return uint2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_6fe804() {
+  uint2 res = tint_first_leading_bit(uint2());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_6fe804();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_6fe804();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_6fe804();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl.expected.spvasm

@@ -0,0 +1,142 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 99
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_6fe804 "firstLeadingBit_6fe804"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+       %uint = OpTypeInt 32 0
+     %v2uint = OpTypeVector %uint 2
+          %9 = OpTypeFunction %v2uint %v2uint
+%_ptr_Function_v2uint = OpTypePointer Function %v2uint
+         %17 = OpConstantNull %v2uint
+       %bool = OpTypeBool
+     %v2bool = OpTypeVector %bool 2
+%uint_4294901760 = OpConstant %uint 4294901760
+         %24 = OpConstantComposite %v2uint %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %27 = OpConstantComposite %v2uint %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %29 = OpConstantComposite %v2uint %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %36 = OpConstantComposite %v2uint %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %39 = OpConstantComposite %v2uint %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %46 = OpConstantComposite %v2uint %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %49 = OpConstantComposite %v2uint %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %56 = OpConstantComposite %v2uint %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %59 = OpConstantComposite %v2uint %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %67 = OpConstantComposite %v2uint %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %72 = OpConstantComposite %v2uint %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %79 = OpTypeFunction %void
+         %85 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v2uint None %9
+          %v = OpFunctionParameter %v2uint
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v2uint Function %17
+               OpStore %x %v
+         %22 = OpLoad %v2uint %x
+         %25 = OpBitwiseAnd %v2uint %22 %24
+         %19 = OpINotEqual %v2bool %25 %17
+         %18 = OpSelect %v2uint %19 %27 %29
+         %30 = OpLoad %v2uint %x
+         %31 = OpShiftRightLogical %v2uint %30 %18
+               OpStore %x %31
+         %34 = OpLoad %v2uint %x
+         %37 = OpBitwiseAnd %v2uint %34 %36
+         %33 = OpINotEqual %v2bool %37 %17
+         %32 = OpSelect %v2uint %33 %39 %29
+         %40 = OpLoad %v2uint %x
+         %41 = OpShiftRightLogical %v2uint %40 %32
+               OpStore %x %41
+         %44 = OpLoad %v2uint %x
+         %47 = OpBitwiseAnd %v2uint %44 %46
+         %43 = OpINotEqual %v2bool %47 %17
+         %42 = OpSelect %v2uint %43 %49 %29
+         %50 = OpLoad %v2uint %x
+         %51 = OpShiftRightLogical %v2uint %50 %42
+               OpStore %x %51
+         %54 = OpLoad %v2uint %x
+         %57 = OpBitwiseAnd %v2uint %54 %56
+         %53 = OpINotEqual %v2bool %57 %17
+         %52 = OpSelect %v2uint %53 %59 %29
+         %60 = OpLoad %v2uint %x
+         %61 = OpShiftRightLogical %v2uint %60 %52
+               OpStore %x %61
+         %64 = OpLoad %v2uint %x
+         %65 = OpBitwiseAnd %v2uint %64 %59
+         %63 = OpINotEqual %v2bool %65 %17
+         %62 = OpSelect %v2uint %63 %67 %29
+         %69 = OpLoad %v2uint %x
+         %70 = OpIEqual %v2bool %69 %29
+         %68 = OpSelect %v2uint %70 %72 %29
+         %74 = OpBitwiseOr %v2uint %18 %32
+         %75 = OpBitwiseOr %v2uint %74 %42
+         %76 = OpBitwiseOr %v2uint %75 %52
+         %77 = OpBitwiseOr %v2uint %76 %62
+         %78 = OpBitwiseOr %v2uint %77 %68
+               OpReturnValue %78
+               OpFunctionEnd
+%firstLeadingBit_6fe804 = OpFunction %void None %79
+         %82 = OpLabel
+        %res = OpVariable %_ptr_Function_v2uint Function %17
+         %83 = OpFunctionCall %v2uint %tint_first_leading_bit %17
+               OpStore %res %83
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %85
+         %87 = OpLabel
+         %88 = OpFunctionCall %void %firstLeadingBit_6fe804
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %79
+         %90 = OpLabel
+         %91 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %91
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %79
+         %94 = OpLabel
+         %95 = OpFunctionCall %void %firstLeadingBit_6fe804
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %79
+         %97 = OpLabel
+         %98 = OpFunctionCall %void %firstLeadingBit_6fe804
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/6fe804.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_6fe804() {
+  var res : vec2<u32> = firstLeadingBit(vec2<u32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_6fe804();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_6fe804();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_6fe804();
+}

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<2, i32>) -> vec<2, i32>
+fn firstLeadingBit_a622c2() {
+  var res: vec2<i32> = firstLeadingBit(vec2<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_a622c2();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_a622c2();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_a622c2();
+}

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+ivec2 tint_first_leading_bit(ivec2 v) {
+  uvec2 x = mix(uvec2(v), uvec2(~(v)), lessThan(v, ivec2(0)));
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return ivec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_a622c2() {
+  ivec2 res = tint_first_leading_bit(ivec2(0, 0));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_a622c2();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+ivec2 tint_first_leading_bit(ivec2 v) {
+  uvec2 x = mix(uvec2(v), uvec2(~(v)), lessThan(v, ivec2(0)));
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return ivec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_a622c2() {
+  ivec2 res = tint_first_leading_bit(ivec2(0, 0));
+}
+
+void fragment_main() {
+  firstLeadingBit_a622c2();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+ivec2 tint_first_leading_bit(ivec2 v) {
+  uvec2 x = mix(uvec2(v), uvec2(~(v)), lessThan(v, ivec2(0)));
+  uvec2 b16 = mix(uvec2(0u), uvec2(16u), bvec2((x & uvec2(4294901760u))));
+  x = (x >> b16);
+  uvec2 b8 = mix(uvec2(0u), uvec2(8u), bvec2((x & uvec2(65280u))));
+  x = (x >> b8);
+  uvec2 b4 = mix(uvec2(0u), uvec2(4u), bvec2((x & uvec2(240u))));
+  x = (x >> b4);
+  uvec2 b2 = mix(uvec2(0u), uvec2(2u), bvec2((x & uvec2(12u))));
+  x = (x >> b2);
+  uvec2 b1 = mix(uvec2(0u), uvec2(1u), bvec2((x & uvec2(2u))));
+  uvec2 is_zero = mix(uvec2(0u), uvec2(4294967295u), equal(x, uvec2(0u)));
+  return ivec2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_a622c2() {
+  ivec2 res = tint_first_leading_bit(ivec2(0, 0));
+}
+
+void compute_main() {
+  firstLeadingBit_a622c2();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+int2 tint_first_leading_bit(int2 v) {
+  uint2 x = ((v < int2((0).xx)) ? uint2(~(v)) : uint2(v));
+  const uint2 b16 = (bool2((x & uint2((4294901760u).xx))) ? uint2((16u).xx) : uint2((0u).xx));
+  x = (x >> b16);
+  const uint2 b8 = (bool2((x & uint2((65280u).xx))) ? uint2((8u).xx) : uint2((0u).xx));
+  x = (x >> b8);
+  const uint2 b4 = (bool2((x & uint2((240u).xx))) ? uint2((4u).xx) : uint2((0u).xx));
+  x = (x >> b4);
+  const uint2 b2 = (bool2((x & uint2((12u).xx))) ? uint2((2u).xx) : uint2((0u).xx));
+  x = (x >> b2);
+  const uint2 b1 = (bool2((x & uint2((2u).xx))) ? uint2((1u).xx) : uint2((0u).xx));
+  const uint2 is_zero = ((x == uint2((0u).xx)) ? uint2((4294967295u).xx) : uint2((0u).xx));
+  return int2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_a622c2() {
+  int2 res = tint_first_leading_bit(int2(0, 0));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_a622c2();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_a622c2();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_a622c2();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+int2 tint_first_leading_bit(int2 v) {
+  uint2 x = select(uint2(v), uint2(~(v)), (v < int2(0)));
+  uint2 const b16 = select(uint2(0u), uint2(16u), bool2((x & uint2(4294901760u))));
+  x = (x >> b16);
+  uint2 const b8 = select(uint2(0u), uint2(8u), bool2((x & uint2(65280u))));
+  x = (x >> b8);
+  uint2 const b4 = select(uint2(0u), uint2(4u), bool2((x & uint2(240u))));
+  x = (x >> b4);
+  uint2 const b2 = select(uint2(0u), uint2(2u), bool2((x & uint2(12u))));
+  x = (x >> b2);
+  uint2 const b1 = select(uint2(0u), uint2(1u), bool2((x & uint2(2u))));
+  uint2 const is_zero = select(uint2(0u), uint2(4294967295u), (x == uint2(0u)));
+  return int2((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_a622c2() {
+  int2 res = tint_first_leading_bit(int2());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_a622c2();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_a622c2();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_a622c2();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl.expected.spvasm

@@ -0,0 +1,154 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 110
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_a622c2 "firstLeadingBit_a622c2"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+        %int = OpTypeInt 32 1
+      %v2int = OpTypeVector %int 2
+          %9 = OpTypeFunction %v2int %v2int
+       %uint = OpTypeInt 32 0
+     %v2uint = OpTypeVector %uint 2
+      %int_0 = OpConstant %int 0
+         %19 = OpConstantComposite %v2int %int_0 %int_0
+       %bool = OpTypeBool
+     %v2bool = OpTypeVector %bool 2
+%_ptr_Function_v2uint = OpTypePointer Function %v2uint
+         %28 = OpConstantNull %v2uint
+%uint_4294901760 = OpConstant %uint 4294901760
+         %33 = OpConstantComposite %v2uint %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %36 = OpConstantComposite %v2uint %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %38 = OpConstantComposite %v2uint %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %45 = OpConstantComposite %v2uint %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %48 = OpConstantComposite %v2uint %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %55 = OpConstantComposite %v2uint %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %58 = OpConstantComposite %v2uint %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %65 = OpConstantComposite %v2uint %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %68 = OpConstantComposite %v2uint %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %76 = OpConstantComposite %v2uint %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %81 = OpConstantComposite %v2uint %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %88 = OpTypeFunction %void
+         %93 = OpConstantNull %v2int
+%_ptr_Function_v2int = OpTypePointer Function %v2int
+         %96 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v2int None %9
+          %v = OpFunctionParameter %v2int
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v2uint Function %28
+         %20 = OpSLessThan %v2bool %v %19
+         %24 = OpNot %v2int %v
+         %23 = OpBitcast %v2uint %24
+         %25 = OpBitcast %v2uint %v
+         %15 = OpSelect %v2uint %20 %23 %25
+               OpStore %x %15
+         %31 = OpLoad %v2uint %x
+         %34 = OpBitwiseAnd %v2uint %31 %33
+         %30 = OpINotEqual %v2bool %34 %28
+         %29 = OpSelect %v2uint %30 %36 %38
+         %39 = OpLoad %v2uint %x
+         %40 = OpShiftRightLogical %v2uint %39 %29
+               OpStore %x %40
+         %43 = OpLoad %v2uint %x
+         %46 = OpBitwiseAnd %v2uint %43 %45
+         %42 = OpINotEqual %v2bool %46 %28
+         %41 = OpSelect %v2uint %42 %48 %38
+         %49 = OpLoad %v2uint %x
+         %50 = OpShiftRightLogical %v2uint %49 %41
+               OpStore %x %50
+         %53 = OpLoad %v2uint %x
+         %56 = OpBitwiseAnd %v2uint %53 %55
+         %52 = OpINotEqual %v2bool %56 %28
+         %51 = OpSelect %v2uint %52 %58 %38
+         %59 = OpLoad %v2uint %x
+         %60 = OpShiftRightLogical %v2uint %59 %51
+               OpStore %x %60
+         %63 = OpLoad %v2uint %x
+         %66 = OpBitwiseAnd %v2uint %63 %65
+         %62 = OpINotEqual %v2bool %66 %28
+         %61 = OpSelect %v2uint %62 %68 %38
+         %69 = OpLoad %v2uint %x
+         %70 = OpShiftRightLogical %v2uint %69 %61
+               OpStore %x %70
+         %73 = OpLoad %v2uint %x
+         %74 = OpBitwiseAnd %v2uint %73 %68
+         %72 = OpINotEqual %v2bool %74 %28
+         %71 = OpSelect %v2uint %72 %76 %38
+         %78 = OpLoad %v2uint %x
+         %79 = OpIEqual %v2bool %78 %38
+         %77 = OpSelect %v2uint %79 %81 %38
+         %83 = OpBitwiseOr %v2uint %29 %41
+         %84 = OpBitwiseOr %v2uint %83 %51
+         %85 = OpBitwiseOr %v2uint %84 %61
+         %86 = OpBitwiseOr %v2uint %85 %71
+         %87 = OpBitwiseOr %v2uint %86 %77
+         %82 = OpBitcast %v2int %87
+               OpReturnValue %82
+               OpFunctionEnd
+%firstLeadingBit_a622c2 = OpFunction %void None %88
+         %91 = OpLabel
+        %res = OpVariable %_ptr_Function_v2int Function %93
+         %92 = OpFunctionCall %v2int %tint_first_leading_bit %93
+               OpStore %res %92
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %96
+         %98 = OpLabel
+         %99 = OpFunctionCall %void %firstLeadingBit_a622c2
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %88
+        %101 = OpLabel
+        %102 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %102
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %88
+        %105 = OpLabel
+        %106 = OpFunctionCall %void %firstLeadingBit_a622c2
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %88
+        %108 = OpLabel
+        %109 = OpFunctionCall %void %firstLeadingBit_a622c2
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/a622c2.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_a622c2() {
+  var res : vec2<i32> = firstLeadingBit(vec2<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_a622c2();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_a622c2();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_a622c2();
+}

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(vec<4, i32>) -> vec<4, i32>
+fn firstLeadingBit_c1f940() {
+  var res: vec4<i32> = firstLeadingBit(vec4<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_c1f940();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_c1f940();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_c1f940();
+}

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+ivec4 tint_first_leading_bit(ivec4 v) {
+  uvec4 x = mix(uvec4(v), uvec4(~(v)), lessThan(v, ivec4(0)));
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return ivec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_c1f940() {
+  ivec4 res = tint_first_leading_bit(ivec4(0, 0, 0, 0));
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_c1f940();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+ivec4 tint_first_leading_bit(ivec4 v) {
+  uvec4 x = mix(uvec4(v), uvec4(~(v)), lessThan(v, ivec4(0)));
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return ivec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_c1f940() {
+  ivec4 res = tint_first_leading_bit(ivec4(0, 0, 0, 0));
+}
+
+void fragment_main() {
+  firstLeadingBit_c1f940();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+ivec4 tint_first_leading_bit(ivec4 v) {
+  uvec4 x = mix(uvec4(v), uvec4(~(v)), lessThan(v, ivec4(0)));
+  uvec4 b16 = mix(uvec4(0u), uvec4(16u), bvec4((x & uvec4(4294901760u))));
+  x = (x >> b16);
+  uvec4 b8 = mix(uvec4(0u), uvec4(8u), bvec4((x & uvec4(65280u))));
+  x = (x >> b8);
+  uvec4 b4 = mix(uvec4(0u), uvec4(4u), bvec4((x & uvec4(240u))));
+  x = (x >> b4);
+  uvec4 b2 = mix(uvec4(0u), uvec4(2u), bvec4((x & uvec4(12u))));
+  x = (x >> b2);
+  uvec4 b1 = mix(uvec4(0u), uvec4(1u), bvec4((x & uvec4(2u))));
+  uvec4 is_zero = mix(uvec4(0u), uvec4(4294967295u), equal(x, uvec4(0u)));
+  return ivec4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_c1f940() {
+  ivec4 res = tint_first_leading_bit(ivec4(0, 0, 0, 0));
+}
+
+void compute_main() {
+  firstLeadingBit_c1f940();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+int4 tint_first_leading_bit(int4 v) {
+  uint4 x = ((v < int4((0).xxxx)) ? uint4(~(v)) : uint4(v));
+  const uint4 b16 = (bool4((x & uint4((4294901760u).xxxx))) ? uint4((16u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b16);
+  const uint4 b8 = (bool4((x & uint4((65280u).xxxx))) ? uint4((8u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b8);
+  const uint4 b4 = (bool4((x & uint4((240u).xxxx))) ? uint4((4u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b4);
+  const uint4 b2 = (bool4((x & uint4((12u).xxxx))) ? uint4((2u).xxxx) : uint4((0u).xxxx));
+  x = (x >> b2);
+  const uint4 b1 = (bool4((x & uint4((2u).xxxx))) ? uint4((1u).xxxx) : uint4((0u).xxxx));
+  const uint4 is_zero = ((x == uint4((0u).xxxx)) ? uint4((4294967295u).xxxx) : uint4((0u).xxxx));
+  return int4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_c1f940() {
+  int4 res = tint_first_leading_bit(int4(0, 0, 0, 0));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_c1f940();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_c1f940();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_c1f940();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+int4 tint_first_leading_bit(int4 v) {
+  uint4 x = select(uint4(v), uint4(~(v)), (v < int4(0)));
+  uint4 const b16 = select(uint4(0u), uint4(16u), bool4((x & uint4(4294901760u))));
+  x = (x >> b16);
+  uint4 const b8 = select(uint4(0u), uint4(8u), bool4((x & uint4(65280u))));
+  x = (x >> b8);
+  uint4 const b4 = select(uint4(0u), uint4(4u), bool4((x & uint4(240u))));
+  x = (x >> b4);
+  uint4 const b2 = select(uint4(0u), uint4(2u), bool4((x & uint4(12u))));
+  x = (x >> b2);
+  uint4 const b1 = select(uint4(0u), uint4(1u), bool4((x & uint4(2u))));
+  uint4 const is_zero = select(uint4(0u), uint4(4294967295u), (x == uint4(0u)));
+  return int4((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_c1f940() {
+  int4 res = tint_first_leading_bit(int4());
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_c1f940();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_c1f940();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_c1f940();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl.expected.spvasm

@@ -0,0 +1,154 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 110
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_c1f940 "firstLeadingBit_c1f940"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+        %int = OpTypeInt 32 1
+      %v4int = OpTypeVector %int 4
+          %9 = OpTypeFunction %v4int %v4int
+       %uint = OpTypeInt 32 0
+     %v4uint = OpTypeVector %uint 4
+      %int_0 = OpConstant %int 0
+         %19 = OpConstantComposite %v4int %int_0 %int_0 %int_0 %int_0
+       %bool = OpTypeBool
+     %v4bool = OpTypeVector %bool 4
+%_ptr_Function_v4uint = OpTypePointer Function %v4uint
+         %28 = OpConstantNull %v4uint
+%uint_4294901760 = OpConstant %uint 4294901760
+         %33 = OpConstantComposite %v4uint %uint_4294901760 %uint_4294901760 %uint_4294901760 %uint_4294901760
+    %uint_16 = OpConstant %uint 16
+         %36 = OpConstantComposite %v4uint %uint_16 %uint_16 %uint_16 %uint_16
+     %uint_0 = OpConstant %uint 0
+         %38 = OpConstantComposite %v4uint %uint_0 %uint_0 %uint_0 %uint_0
+ %uint_65280 = OpConstant %uint 65280
+         %45 = OpConstantComposite %v4uint %uint_65280 %uint_65280 %uint_65280 %uint_65280
+     %uint_8 = OpConstant %uint 8
+         %48 = OpConstantComposite %v4uint %uint_8 %uint_8 %uint_8 %uint_8
+   %uint_240 = OpConstant %uint 240
+         %55 = OpConstantComposite %v4uint %uint_240 %uint_240 %uint_240 %uint_240
+     %uint_4 = OpConstant %uint 4
+         %58 = OpConstantComposite %v4uint %uint_4 %uint_4 %uint_4 %uint_4
+    %uint_12 = OpConstant %uint 12
+         %65 = OpConstantComposite %v4uint %uint_12 %uint_12 %uint_12 %uint_12
+     %uint_2 = OpConstant %uint 2
+         %68 = OpConstantComposite %v4uint %uint_2 %uint_2 %uint_2 %uint_2
+     %uint_1 = OpConstant %uint 1
+         %76 = OpConstantComposite %v4uint %uint_1 %uint_1 %uint_1 %uint_1
+%uint_4294967295 = OpConstant %uint 4294967295
+         %81 = OpConstantComposite %v4uint %uint_4294967295 %uint_4294967295 %uint_4294967295 %uint_4294967295
+       %void = OpTypeVoid
+         %88 = OpTypeFunction %void
+         %93 = OpConstantNull %v4int
+%_ptr_Function_v4int = OpTypePointer Function %v4int
+         %96 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %v4int None %9
+          %v = OpFunctionParameter %v4int
+         %14 = OpLabel
+          %x = OpVariable %_ptr_Function_v4uint Function %28
+         %20 = OpSLessThan %v4bool %v %19
+         %24 = OpNot %v4int %v
+         %23 = OpBitcast %v4uint %24
+         %25 = OpBitcast %v4uint %v
+         %15 = OpSelect %v4uint %20 %23 %25
+               OpStore %x %15
+         %31 = OpLoad %v4uint %x
+         %34 = OpBitwiseAnd %v4uint %31 %33
+         %30 = OpINotEqual %v4bool %34 %28
+         %29 = OpSelect %v4uint %30 %36 %38
+         %39 = OpLoad %v4uint %x
+         %40 = OpShiftRightLogical %v4uint %39 %29
+               OpStore %x %40
+         %43 = OpLoad %v4uint %x
+         %46 = OpBitwiseAnd %v4uint %43 %45
+         %42 = OpINotEqual %v4bool %46 %28
+         %41 = OpSelect %v4uint %42 %48 %38
+         %49 = OpLoad %v4uint %x
+         %50 = OpShiftRightLogical %v4uint %49 %41
+               OpStore %x %50
+         %53 = OpLoad %v4uint %x
+         %56 = OpBitwiseAnd %v4uint %53 %55
+         %52 = OpINotEqual %v4bool %56 %28
+         %51 = OpSelect %v4uint %52 %58 %38
+         %59 = OpLoad %v4uint %x
+         %60 = OpShiftRightLogical %v4uint %59 %51
+               OpStore %x %60
+         %63 = OpLoad %v4uint %x
+         %66 = OpBitwiseAnd %v4uint %63 %65
+         %62 = OpINotEqual %v4bool %66 %28
+         %61 = OpSelect %v4uint %62 %68 %38
+         %69 = OpLoad %v4uint %x
+         %70 = OpShiftRightLogical %v4uint %69 %61
+               OpStore %x %70
+         %73 = OpLoad %v4uint %x
+         %74 = OpBitwiseAnd %v4uint %73 %68
+         %72 = OpINotEqual %v4bool %74 %28
+         %71 = OpSelect %v4uint %72 %76 %38
+         %78 = OpLoad %v4uint %x
+         %79 = OpIEqual %v4bool %78 %38
+         %77 = OpSelect %v4uint %79 %81 %38
+         %83 = OpBitwiseOr %v4uint %29 %41
+         %84 = OpBitwiseOr %v4uint %83 %51
+         %85 = OpBitwiseOr %v4uint %84 %61
+         %86 = OpBitwiseOr %v4uint %85 %71
+         %87 = OpBitwiseOr %v4uint %86 %77
+         %82 = OpBitcast %v4int %87
+               OpReturnValue %82
+               OpFunctionEnd
+%firstLeadingBit_c1f940 = OpFunction %void None %88
+         %91 = OpLabel
+        %res = OpVariable %_ptr_Function_v4int Function %93
+         %92 = OpFunctionCall %v4int %tint_first_leading_bit %93
+               OpStore %res %92
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %96
+         %98 = OpLabel
+         %99 = OpFunctionCall %void %firstLeadingBit_c1f940
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %88
+        %101 = OpLabel
+        %102 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %102
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %88
+        %105 = OpLabel
+        %106 = OpFunctionCall %void %firstLeadingBit_c1f940
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %88
+        %108 = OpLabel
+        %109 = OpFunctionCall %void %firstLeadingBit_c1f940
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/c1f940.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_c1f940() {
+  var res : vec4<i32> = firstLeadingBit(vec4<i32>());
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_c1f940();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_c1f940();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_c1f940();
+}

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl

@@ -0,0 +1,45 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+////////////////////////////////////////////////////////////////////////////////
+// File generated by tools/builtin-gen
+// using the template:
+//   test/tint/builtins/builtins.wgsl.tmpl
+// and the builtin defintion file:
+//   src/tint/builtins.def
+//
+// Do not modify this file directly
+////////////////////////////////////////////////////////////////////////////////
+
+
+// fn firstLeadingBit(u32) -> u32
+fn firstLeadingBit_f0779d() {
+  var res: u32 = firstLeadingBit(1u);
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_f0779d();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_f0779d();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_f0779d();
+}

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl.expected.glsl

@@ -0,0 +1,93 @@
+#version 310 es
+
+uint tint_first_leading_bit(uint v) {
+  uint x = v;
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return uint((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_f0779d() {
+  uint res = tint_first_leading_bit(1u);
+}
+
+vec4 vertex_main() {
+  firstLeadingBit_f0779d();
+  return vec4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void main() {
+  vec4 inner_result = vertex_main();
+  gl_Position = inner_result;
+  gl_Position.y = -(gl_Position.y);
+  gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
+  return;
+}
+#version 310 es
+precision mediump float;
+
+uint tint_first_leading_bit(uint v) {
+  uint x = v;
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return uint((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_f0779d() {
+  uint res = tint_first_leading_bit(1u);
+}
+
+void fragment_main() {
+  firstLeadingBit_f0779d();
+}
+
+void main() {
+  fragment_main();
+  return;
+}
+#version 310 es
+
+uint tint_first_leading_bit(uint v) {
+  uint x = v;
+  uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return uint((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_f0779d() {
+  uint res = tint_first_leading_bit(1u);
+}
+
+void compute_main() {
+  firstLeadingBit_f0779d();
+}
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void main() {
+  compute_main();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl.expected.hlsl

@@ -0,0 +1,45 @@
+uint tint_first_leading_bit(uint v) {
+  uint x = v;
+  const uint b16 = (bool((x & 4294901760u)) ? 16u : 0u);
+  x = (x >> b16);
+  const uint b8 = (bool((x & 65280u)) ? 8u : 0u);
+  x = (x >> b8);
+  const uint b4 = (bool((x & 240u)) ? 4u : 0u);
+  x = (x >> b4);
+  const uint b2 = (bool((x & 12u)) ? 2u : 0u);
+  x = (x >> b2);
+  const uint b1 = (bool((x & 2u)) ? 1u : 0u);
+  const uint is_zero = ((x == 0u) ? 4294967295u : 0u);
+  return uint((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_f0779d() {
+  uint res = tint_first_leading_bit(1u);
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_f0779d();
+  return float4(0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+tint_symbol vertex_main() {
+  const float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  firstLeadingBit_f0779d();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  firstLeadingBit_f0779d();
+  return;
+}

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl.expected.msl

@@ -0,0 +1,48 @@
+#include <metal_stdlib>
+
+using namespace metal;
+uint tint_first_leading_bit(uint v) {
+  uint x = v;
+  uint const b16 = select(0u, 16u, bool((x & 4294901760u)));
+  x = (x >> b16);
+  uint const b8 = select(0u, 8u, bool((x & 65280u)));
+  x = (x >> b8);
+  uint const b4 = select(0u, 4u, bool((x & 240u)));
+  x = (x >> b4);
+  uint const b2 = select(0u, 2u, bool((x & 12u)));
+  x = (x >> b2);
+  uint const b1 = select(0u, 1u, bool((x & 2u)));
+  uint const is_zero = select(0u, 4294967295u, (x == 0u));
+  return uint((((((b16 | b8) | b4) | b2) | b1) | is_zero));
+}
+
+void firstLeadingBit_f0779d() {
+  uint res = tint_first_leading_bit(1u);
+}
+
+struct tint_symbol {
+  float4 value [[position]];
+};
+
+float4 vertex_main_inner() {
+  firstLeadingBit_f0779d();
+  return float4();
+}
+
+vertex tint_symbol vertex_main() {
+  float4 const inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = {};
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+fragment void fragment_main() {
+  firstLeadingBit_f0779d();
+  return;
+}
+
+kernel void compute_main() {
+  firstLeadingBit_f0779d();
+  return;
+}
+

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl.expected.spvasm

@@ -0,0 +1,129 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 86
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
+               OpEntryPoint Fragment %fragment_main "fragment_main"
+               OpEntryPoint GLCompute %compute_main "compute_main"
+               OpExecutionMode %fragment_main OriginUpperLeft
+               OpExecutionMode %compute_main LocalSize 1 1 1
+               OpName %value "value"
+               OpName %vertex_point_size "vertex_point_size"
+               OpName %tint_first_leading_bit "tint_first_leading_bit"
+               OpName %v "v"
+               OpName %x "x"
+               OpName %firstLeadingBit_f0779d "firstLeadingBit_f0779d"
+               OpName %res "res"
+               OpName %vertex_main_inner "vertex_main_inner"
+               OpName %vertex_main "vertex_main"
+               OpName %fragment_main "fragment_main"
+               OpName %compute_main "compute_main"
+               OpDecorate %value BuiltIn Position
+               OpDecorate %vertex_point_size BuiltIn PointSize
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+          %5 = OpConstantNull %v4float
+      %value = OpVariable %_ptr_Output_v4float Output %5
+%_ptr_Output_float = OpTypePointer Output %float
+          %8 = OpConstantNull %float
+%vertex_point_size = OpVariable %_ptr_Output_float Output %8
+       %uint = OpTypeInt 32 0
+          %9 = OpTypeFunction %uint %uint
+%_ptr_Function_uint = OpTypePointer Function %uint
+         %16 = OpConstantNull %uint
+       %bool = OpTypeBool
+%uint_4294901760 = OpConstant %uint 4294901760
+    %uint_16 = OpConstant %uint 16
+     %uint_0 = OpConstant %uint 0
+ %uint_65280 = OpConstant %uint 65280
+     %uint_8 = OpConstant %uint 8
+   %uint_240 = OpConstant %uint 240
+     %uint_4 = OpConstant %uint 4
+    %uint_12 = OpConstant %uint 12
+     %uint_2 = OpConstant %uint 2
+     %uint_1 = OpConstant %uint 1
+%uint_4294967295 = OpConstant %uint 4294967295
+       %void = OpTypeVoid
+         %66 = OpTypeFunction %void
+         %72 = OpTypeFunction %v4float
+    %float_1 = OpConstant %float 1
+%tint_first_leading_bit = OpFunction %uint None %9
+          %v = OpFunctionParameter %uint
+         %13 = OpLabel
+          %x = OpVariable %_ptr_Function_uint Function %16
+               OpStore %x %v
+         %20 = OpLoad %uint %x
+         %22 = OpBitwiseAnd %uint %20 %uint_4294901760
+         %18 = OpINotEqual %bool %22 %16
+         %17 = OpSelect %uint %18 %uint_16 %uint_0
+         %25 = OpLoad %uint %x
+         %26 = OpShiftRightLogical %uint %25 %17
+               OpStore %x %26
+         %29 = OpLoad %uint %x
+         %31 = OpBitwiseAnd %uint %29 %uint_65280
+         %28 = OpINotEqual %bool %31 %16
+         %27 = OpSelect %uint %28 %uint_8 %uint_0
+         %33 = OpLoad %uint %x
+         %34 = OpShiftRightLogical %uint %33 %27
+               OpStore %x %34
+         %37 = OpLoad %uint %x
+         %39 = OpBitwiseAnd %uint %37 %uint_240
+         %36 = OpINotEqual %bool %39 %16
+         %35 = OpSelect %uint %36 %uint_4 %uint_0
+         %41 = OpLoad %uint %x
+         %42 = OpShiftRightLogical %uint %41 %35
+               OpStore %x %42
+         %45 = OpLoad %uint %x
+         %47 = OpBitwiseAnd %uint %45 %uint_12
+         %44 = OpINotEqual %bool %47 %16
+         %43 = OpSelect %uint %44 %uint_2 %uint_0
+         %49 = OpLoad %uint %x
+         %50 = OpShiftRightLogical %uint %49 %43
+               OpStore %x %50
+         %53 = OpLoad %uint %x
+         %54 = OpBitwiseAnd %uint %53 %uint_2
+         %52 = OpINotEqual %bool %54 %16
+         %51 = OpSelect %uint %52 %uint_1 %uint_0
+         %57 = OpLoad %uint %x
+         %58 = OpIEqual %bool %57 %uint_0
+         %56 = OpSelect %uint %58 %uint_4294967295 %uint_0
+         %61 = OpBitwiseOr %uint %17 %27
+         %62 = OpBitwiseOr %uint %61 %35
+         %63 = OpBitwiseOr %uint %62 %43
+         %64 = OpBitwiseOr %uint %63 %51
+         %65 = OpBitwiseOr %uint %64 %56
+               OpReturnValue %65
+               OpFunctionEnd
+%firstLeadingBit_f0779d = OpFunction %void None %66
+         %69 = OpLabel
+        %res = OpVariable %_ptr_Function_uint Function %16
+         %70 = OpFunctionCall %uint %tint_first_leading_bit %uint_1
+               OpStore %res %70
+               OpReturn
+               OpFunctionEnd
+%vertex_main_inner = OpFunction %v4float None %72
+         %74 = OpLabel
+         %75 = OpFunctionCall %void %firstLeadingBit_f0779d
+               OpReturnValue %5
+               OpFunctionEnd
+%vertex_main = OpFunction %void None %66
+         %77 = OpLabel
+         %78 = OpFunctionCall %v4float %vertex_main_inner
+               OpStore %value %78
+               OpStore %vertex_point_size %float_1
+               OpReturn
+               OpFunctionEnd
+%fragment_main = OpFunction %void None %66
+         %81 = OpLabel
+         %82 = OpFunctionCall %void %firstLeadingBit_f0779d
+               OpReturn
+               OpFunctionEnd
+%compute_main = OpFunction %void None %66
+         %84 = OpLabel
+         %85 = OpFunctionCall %void %firstLeadingBit_f0779d
+               OpReturn
+               OpFunctionEnd

test/tint/builtins/gen/firstLeadingBit/f0779d.wgsl.expected.wgsl

@@ -0,0 +1,19 @@
+fn firstLeadingBit_f0779d() {
+  var res : u32 = firstLeadingBit(1u);
+}
+
+@stage(vertex)
+fn vertex_main() -> @builtin(position) vec4<f32> {
+  firstLeadingBit_f0779d();
+  return vec4<f32>();
+}
+
+@stage(fragment)
+fn fragment_main() {
+  firstLeadingBit_f0779d();
+}
+
+@stage(compute) @workgroup_size(1)
+fn compute_main() {
+  firstLeadingBit_f0779d();
+}