Implemement const-eval for some unpack routines.

This CL adds const-eval for unpack2x16snorm, unpack2x16unorm,
unpack4x8snorm and unpack4x8unorm.

Bug: tint:1581
Change-Id: Ieda938b797dfe3f8d8046101d12b99da69ad68f4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/108864
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>

src/tint/intrinsics.def

@@ -550,10 +550,10 @@ fn transpose<M: num, N: num, T: f32_f16>(mat<M, N, T>) -> mat<N, M, T>
 fn trunc<T: f32_f16>(T) -> T
 fn trunc<N: num, T: f32_f16>(vec<N, T>) -> vec<N, T>
 fn unpack2x16float(u32) -> vec2<f32>
-fn unpack2x16snorm(u32) -> vec2<f32>
+@const fn unpack2x16snorm(u32) -> vec2<f32>
-fn unpack2x16unorm(u32) -> vec2<f32>
+@const fn unpack2x16unorm(u32) -> vec2<f32>
-fn unpack4x8snorm(u32) -> vec4<f32>
+@const fn unpack4x8snorm(u32) -> vec4<f32>
-fn unpack4x8unorm(u32) -> vec4<f32>
+@const fn unpack4x8unorm(u32) -> vec4<f32>
 @stage("compute") fn workgroupBarrier()
 
 fn textureDimensions<T: fiu32>(texture: texture_1d<T>) -> u32

src/tint/resolver/const_eval.cc

@@ -2168,6 +2168,68 @@ ConstEval::Result ConstEval::step(const sem::Type* ty,
     return TransformElements(builder, ty, transform, args[0], args[1]);
 }
 
+ConstEval::Result ConstEval::unpack2x16snorm(const sem::Type* ty,
+                                             utils::VectorRef<const sem::Constant*> args,
+                                             const Source&) {
+    auto* inner_ty = sem::Type::DeepestElementOf(ty);
+    auto e = args[0]->As<u32>().value;
+
+    utils::Vector<const sem::Constant*, 2> els;
+    els.Reserve(2);
+    for (size_t i = 0; i < 2; ++i) {
+        auto val = f32(
+            std::max(static_cast<float>(int16_t((e >> (16 * i)) & 0x0000'ffff)) / 32767.f, -1.f));
+        els.Push(CreateElement(builder, inner_ty, val));
+    }
+    return CreateComposite(builder, ty, std::move(els));
+}
+
+ConstEval::Result ConstEval::unpack2x16unorm(const sem::Type* ty,
+                                             utils::VectorRef<const sem::Constant*> args,
+                                             const Source&) {
+    auto* inner_ty = sem::Type::DeepestElementOf(ty);
+    auto e = args[0]->As<u32>().value;
+
+    utils::Vector<const sem::Constant*, 2> els;
+    els.Reserve(2);
+    for (size_t i = 0; i < 2; ++i) {
+        auto val = f32(static_cast<float>(uint16_t((e >> (16 * i)) & 0x0000'ffff)) / 65535.f);
+        els.Push(CreateElement(builder, inner_ty, val));
+    }
+    return CreateComposite(builder, ty, std::move(els));
+}
+
+ConstEval::Result ConstEval::unpack4x8snorm(const sem::Type* ty,
+                                            utils::VectorRef<const sem::Constant*> args,
+                                            const Source&) {
+    auto* inner_ty = sem::Type::DeepestElementOf(ty);
+    auto e = args[0]->As<u32>().value;
+
+    utils::Vector<const sem::Constant*, 4> els;
+    els.Reserve(4);
+    for (size_t i = 0; i < 4; ++i) {
+        auto val =
+            f32(std::max(static_cast<float>(int8_t((e >> (8 * i)) & 0x0000'00ff)) / 127.f, -1.f));
+        els.Push(CreateElement(builder, inner_ty, val));
+    }
+    return CreateComposite(builder, ty, std::move(els));
+}
+
+ConstEval::Result ConstEval::unpack4x8unorm(const sem::Type* ty,
+                                            utils::VectorRef<const sem::Constant*> args,
+                                            const Source&) {
+    auto* inner_ty = sem::Type::DeepestElementOf(ty);
+    auto e = args[0]->As<u32>().value;
+
+    utils::Vector<const sem::Constant*, 4> els;
+    els.Reserve(4);
+    for (size_t i = 0; i < 4; ++i) {
+        auto val = f32(static_cast<float>(uint8_t((e >> (8 * i)) & 0x0000'00ff)) / 255.f);
+        els.Push(CreateElement(builder, inner_ty, val));
+    }
+    return CreateComposite(builder, ty, std::move(els));
+}
+
 ConstEval::Result ConstEval::quantizeToF16(const sem::Type* ty,
                                            utils::VectorRef<const sem::Constant*> args,
                                            const Source&) {

src/tint/resolver/const_eval.h

@@ -638,6 +638,42 @@ class ConstEval {
                 utils::VectorRef<const sem::Constant*> args,
                 const Source& source);
 
+    /// unpack2x16snorm builtin
+    /// @param ty the expression type
+    /// @param args the input arguments
+    /// @param source the source location of the conversion
+    /// @return the result value, or null if the value cannot be calculated
+    Result unpack2x16snorm(const sem::Type* ty,
+                           utils::VectorRef<const sem::Constant*> args,
+                           const Source& source);
+
+    /// unpack2x16unorm builtin
+    /// @param ty the expression type
+    /// @param args the input arguments
+    /// @param source the source location of the conversion
+    /// @return the result value, or null if the value cannot be calculated
+    Result unpack2x16unorm(const sem::Type* ty,
+                           utils::VectorRef<const sem::Constant*> args,
+                           const Source& source);
+
+    /// unpack4x8snorm builtin
+    /// @param ty the expression type
+    /// @param args the input arguments
+    /// @param source the source location of the conversion
+    /// @return the result value, or null if the value cannot be calculated
+    Result unpack4x8snorm(const sem::Type* ty,
+                          utils::VectorRef<const sem::Constant*> args,
+                          const Source& source);
+
+    /// unpack4x8unorm builtin
+    /// @param ty the expression type
+    /// @param args the input arguments
+    /// @param source the source location of the conversion
+    /// @return the result value, or null if the value cannot be calculated
+    Result unpack4x8unorm(const sem::Type* ty,
+                          utils::VectorRef<const sem::Constant*> args,
+                          const Source& source);
+
     /// quantizeToF16 builtin
     /// @param ty the expression type
     /// @param args the input arguments

src/tint/resolver/const_eval_builtin_test.cc

@@ -9,7 +9,7 @@
 // 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
+// See the License for the empecific language governing permissions and
 // limitations under the License.
 
 #include "src/tint/resolver/const_eval_test.h"
@@ -1335,6 +1335,74 @@ INSTANTIATE_TEST_SUITE_P(  //
                                               StepCases<f32>(),
                                               StepCases<f16>()))));
 
+std::vector<Case> Unpack4x8snormCases() {
+    return {
+        C({Val(u32(0x0000'0000))}, Vec(f32(0), f32(0), f32(0), f32(0))),
+        C({Val(u32(0x8100'0000))}, Vec(f32(0), f32(0), f32(0), f32(-1))),
+        C({Val(u32(0x7f00'0000))}, Vec(f32(0), f32(0), f32(0), f32(1))),
+        C({Val(u32(0x0081'0000))}, Vec(f32(0), f32(0), f32(-1), f32(0))),
+        C({Val(u32(0x0000'7f00))}, Vec(f32(0), f32(1), f32(0), f32(0))),
+        C({Val(u32(0x0000'0081))}, Vec(f32(-1), f32(0), f32(0), f32(0))),
+        C({Val(u32(0x817f'817f))}, Vec(f32(1), f32(-1), f32(1), f32(-1))),
+        C({Val(u32(0x816d'937f))},
+          Vec(f32(1), f32(-0.8582677165354), f32(0.8582677165354), f32(-1))),
+    };
+}
+INSTANTIATE_TEST_SUITE_P(  //
+    Unpack4x8snorm,
+    ResolverConstEvalBuiltinTest,
+    testing::Combine(testing::Values(sem::BuiltinType::kUnpack4X8Snorm),
+                     testing::ValuesIn(Unpack4x8snormCases())));
+
+std::vector<Case> Unpack4x8unormCases() {
+    return {
+        C({Val(u32(0x0000'0000))}, Vec(f32(0), f32(0), f32(0), f32(0))),
+        C({Val(u32(0xff00'0000))}, Vec(f32(0), f32(0), f32(0), f32(1))),
+        C({Val(u32(0x00ff'0000))}, Vec(f32(0), f32(0), f32(1), f32(0))),
+        C({Val(u32(0x0000'ff00))}, Vec(f32(0), f32(1), f32(0), f32(0))),
+        C({Val(u32(0x0000'00ff))}, Vec(f32(1), f32(0), f32(0), f32(0))),
+        C({Val(u32(0x00ff'00ff))}, Vec(f32(1), f32(0), f32(1), f32(0))),
+        C({Val(u32(0x0066'00ff))}, Vec(f32(1), f32(0), f32(0.4), f32(0))),
+    };
+}
+INSTANTIATE_TEST_SUITE_P(  //
+    Unpack4x8unorm,
+    ResolverConstEvalBuiltinTest,
+    testing::Combine(testing::Values(sem::BuiltinType::kUnpack4X8Unorm),
+                     testing::ValuesIn(Unpack4x8unormCases())));
+
+std::vector<Case> Unpack2x16snormCases() {
+    return {
+        C({Val(u32(0x0000'0000))}, Vec(f32(0), f32(0))),
+        C({Val(u32(0x8001'0000))}, Vec(f32(0), f32(-1))),
+        C({Val(u32(0x7fff'0000))}, Vec(f32(0), f32(1))),
+        C({Val(u32(0x0000'8001))}, Vec(f32(-1), f32(0))),
+        C({Val(u32(0x0000'7fff))}, Vec(f32(1), f32(0))),
+        C({Val(u32(0x8001'7fff))}, Vec(f32(1), f32(-1))),
+        C({Val(u32(0x8001'7fff))}, Vec(f32(1), f32(-1))),
+        C({Val(u32(0x4000'999a))}, Vec(f32(-0.80001220740379), f32(0.500015259254737))).FloatComp(),
+    };
+}
+INSTANTIATE_TEST_SUITE_P(  //
+    Unpack2x16snorm,
+    ResolverConstEvalBuiltinTest,
+    testing::Combine(testing::Values(sem::BuiltinType::kUnpack2X16Snorm),
+                     testing::ValuesIn(Unpack2x16snormCases())));
+
+std::vector<Case> Unpack2x16unormCases() {
+    return {
+        C({Val(u32(0xffff'0000))}, Vec(f32(0), f32(1))),
+        C({Val(u32(0x0000'ffff))}, Vec(f32(1), f32(0))),
+        C({Val(u32(0x0000'6666))}, Vec(f32(0.4), f32(0))),
+        C({Val(u32(0x0000'ffff))}, Vec(f32(1), f32(0))),
+    };
+}
+INSTANTIATE_TEST_SUITE_P(  //
+    Unpack2x16unorm,
+    ResolverConstEvalBuiltinTest,
+    testing::Combine(testing::Values(sem::BuiltinType::kUnpack2X16Unorm),
+                     testing::ValuesIn(Unpack2x16unormCases())));
+
 std::vector<Case> QuantizeToF16Cases() {
     (void)E({Vec(0_f, 0_f)}, "");  // Currently unused, but will be soon.
     return {

src/tint/resolver/intrinsic_table.inl

@@ -13838,7 +13838,7 @@ constexpr OverloadInfo kOverloads[] = {
     /* parameters */ &kParameters[952],
     /* return matcher indices */ &kMatcherIndices[134],
     /* flags */ OverloadFlags(OverloadFlag::kIsBuiltin, OverloadFlag::kSupportsVertexPipeline, OverloadFlag::kSupportsFragmentPipeline, OverloadFlag::kSupportsComputePipeline),
-    /* const eval */ nullptr,
+    /* const eval */ &ConstEval::unpack4x8unorm,
   },
   {
     /* [459] */
@@ -13850,7 +13850,7 @@ constexpr OverloadInfo kOverloads[] = {
     /* parameters */ &kParameters[962],
     /* return matcher indices */ &kMatcherIndices[134],
     /* flags */ OverloadFlags(OverloadFlag::kIsBuiltin, OverloadFlag::kSupportsVertexPipeline, OverloadFlag::kSupportsFragmentPipeline, OverloadFlag::kSupportsComputePipeline),
-    /* const eval */ nullptr,
+    /* const eval */ &ConstEval::unpack4x8snorm,
   },
   {
     /* [460] */
@@ -13862,7 +13862,7 @@ constexpr OverloadInfo kOverloads[] = {
     /* parameters */ &kParameters[963],
     /* return matcher indices */ &kMatcherIndices[132],
     /* flags */ OverloadFlags(OverloadFlag::kIsBuiltin, OverloadFlag::kSupportsVertexPipeline, OverloadFlag::kSupportsFragmentPipeline, OverloadFlag::kSupportsComputePipeline),
-    /* const eval */ nullptr,
+    /* const eval */ &ConstEval::unpack2x16unorm,
   },
   {
     /* [461] */
@@ -13874,7 +13874,7 @@ constexpr OverloadInfo kOverloads[] = {
     /* parameters */ &kParameters[973],
     /* return matcher indices */ &kMatcherIndices[132],
     /* flags */ OverloadFlags(OverloadFlag::kIsBuiltin, OverloadFlag::kSupportsVertexPipeline, OverloadFlag::kSupportsFragmentPipeline, OverloadFlag::kSupportsComputePipeline),
-    /* const eval */ nullptr,
+    /* const eval */ &ConstEval::unpack2x16snorm,
   },
   {
     /* [462] */

test/tint/builtins/gen/literal/unpack2x16snorm/b4aea6.wgsl.expected.dxc.hlsl

@@ -1,11 +1,5 @@
-float2 tint_unpack2x16snorm(uint param_0) {
-  int j = int(param_0);
-  int2 i = int2(j << 16, j) >> 16;
-  return clamp(float2(i) / 32767.0, -1.0, 1.0);
-}
-
 void unpack2x16snorm_b4aea6() {
-  float2 res = tint_unpack2x16snorm(1u);
+  float2 res = float2(3.05185094e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16snorm/b4aea6.wgsl.expected.fxc.hlsl

@@ -1,11 +1,5 @@
-float2 tint_unpack2x16snorm(uint param_0) {
-  int j = int(param_0);
-  int2 i = int2(j << 16, j) >> 16;
-  return clamp(float2(i) / 32767.0, -1.0, 1.0);
-}
-
 void unpack2x16snorm_b4aea6() {
-  float2 res = tint_unpack2x16snorm(1u);
+  float2 res = float2(3.05185094e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16snorm/b4aea6.wgsl.expected.glsl

@@ -1,7 +1,7 @@
 #version 310 es
 
 void unpack2x16snorm_b4aea6() {
-  vec2 res = unpackSnorm2x16(1u);
+  vec2 res = vec2(3.05185094e-05f, 0.0f);
 }
 
 vec4 vertex_main() {
@@ -21,7 +21,7 @@ void main() {
 precision mediump float;
 
 void unpack2x16snorm_b4aea6() {
-  vec2 res = unpackSnorm2x16(1u);
+  vec2 res = vec2(3.05185094e-05f, 0.0f);
 }
 
 void fragment_main() {
@@ -35,7 +35,7 @@ void main() {
 #version 310 es
 
 void unpack2x16snorm_b4aea6() {
-  vec2 res = unpackSnorm2x16(1u);
+  vec2 res = vec2(3.05185094e-05f, 0.0f);
 }
 
 void compute_main() {

test/tint/builtins/gen/literal/unpack2x16snorm/b4aea6.wgsl.expected.msl

@@ -2,7 +2,7 @@
 
 using namespace metal;
 void unpack2x16snorm_b4aea6() {
-  float2 res = unpack_snorm2x16_to_float(1u);
+  float2 res = float2(3.05185094e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16snorm/b4aea6.wgsl.expected.spvasm

@@ -1,10 +1,9 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 35
+; Bound: 33
 ; Schema: 0
                OpCapability Shader
-         %15 = OpExtInstImport "GLSL.std.450"
                OpMemoryModel Logical GLSL450
                OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
                OpEntryPoint Fragment %fragment_main "fragment_main"
@@ -32,38 +31,37 @@
        %void = OpTypeVoid
           %9 = OpTypeFunction %void
     %v2float = OpTypeVector %float 2
-       %uint = OpTypeInt 32 0
+%float_3_05185094en05 = OpConstant %float 3.05185094e-05
-     %uint_1 = OpConstant %uint 1
+         %15 = OpConstantComposite %v2float %float_3_05185094en05 %8
 %_ptr_Function_v2float = OpTypePointer Function %v2float
-         %20 = OpConstantNull %v2float
+         %18 = OpConstantNull %v2float
-         %21 = OpTypeFunction %v4float
+         %19 = OpTypeFunction %v4float
     %float_1 = OpConstant %float 1
 %unpack2x16snorm_b4aea6 = OpFunction %void None %9
          %12 = OpLabel
-        %res = OpVariable %_ptr_Function_v2float Function %20
+        %res = OpVariable %_ptr_Function_v2float Function %18
-         %13 = OpExtInst %v2float %15 UnpackSnorm2x16 %uint_1
+               OpStore %res %15
-               OpStore %res %13
                OpReturn
                OpFunctionEnd
-%vertex_main_inner = OpFunction %v4float None %21
+%vertex_main_inner = OpFunction %v4float None %19
-         %23 = OpLabel
+         %21 = OpLabel
-         %24 = OpFunctionCall %void %unpack2x16snorm_b4aea6
+         %22 = OpFunctionCall %void %unpack2x16snorm_b4aea6
                OpReturnValue %5
                OpFunctionEnd
 %vertex_main = OpFunction %void None %9
-         %26 = OpLabel
+         %24 = OpLabel
-         %27 = OpFunctionCall %v4float %vertex_main_inner
+         %25 = OpFunctionCall %v4float %vertex_main_inner
-               OpStore %value %27
+               OpStore %value %25
                OpStore %vertex_point_size %float_1
                OpReturn
                OpFunctionEnd
 %fragment_main = OpFunction %void None %9
-         %30 = OpLabel
+         %28 = OpLabel
-         %31 = OpFunctionCall %void %unpack2x16snorm_b4aea6
+         %29 = OpFunctionCall %void %unpack2x16snorm_b4aea6
                OpReturn
                OpFunctionEnd
 %compute_main = OpFunction %void None %9
-         %33 = OpLabel
+         %31 = OpLabel
-         %34 = OpFunctionCall %void %unpack2x16snorm_b4aea6
+         %32 = OpFunctionCall %void %unpack2x16snorm_b4aea6
                OpReturn
                OpFunctionEnd

test/tint/builtins/gen/literal/unpack2x16unorm/7699c0.wgsl.expected.dxc.hlsl

@@ -1,11 +1,5 @@
-float2 tint_unpack2x16unorm(uint param_0) {
-  uint j = param_0;
-  uint2 i = uint2(j & 0xffff, j >> 16);
-  return float2(i) / 65535.0;
-}
-
 void unpack2x16unorm_7699c0() {
-  float2 res = tint_unpack2x16unorm(1u);
+  float2 res = float2(1.52590219e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16unorm/7699c0.wgsl.expected.fxc.hlsl

@@ -1,11 +1,5 @@
-float2 tint_unpack2x16unorm(uint param_0) {
-  uint j = param_0;
-  uint2 i = uint2(j & 0xffff, j >> 16);
-  return float2(i) / 65535.0;
-}
-
 void unpack2x16unorm_7699c0() {
-  float2 res = tint_unpack2x16unorm(1u);
+  float2 res = float2(1.52590219e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16unorm/7699c0.wgsl.expected.glsl

@@ -1,7 +1,7 @@
 #version 310 es
 
 void unpack2x16unorm_7699c0() {
-  vec2 res = unpackUnorm2x16(1u);
+  vec2 res = vec2(1.52590219e-05f, 0.0f);
 }
 
 vec4 vertex_main() {
@@ -21,7 +21,7 @@ void main() {
 precision mediump float;
 
 void unpack2x16unorm_7699c0() {
-  vec2 res = unpackUnorm2x16(1u);
+  vec2 res = vec2(1.52590219e-05f, 0.0f);
 }
 
 void fragment_main() {
@@ -35,7 +35,7 @@ void main() {
 #version 310 es
 
 void unpack2x16unorm_7699c0() {
-  vec2 res = unpackUnorm2x16(1u);
+  vec2 res = vec2(1.52590219e-05f, 0.0f);
 }
 
 void compute_main() {

test/tint/builtins/gen/literal/unpack2x16unorm/7699c0.wgsl.expected.msl

@@ -2,7 +2,7 @@
 
 using namespace metal;
 void unpack2x16unorm_7699c0() {
-  float2 res = unpack_unorm2x16_to_float(1u);
+  float2 res = float2(1.52590219e-05f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack2x16unorm/7699c0.wgsl.expected.spvasm

@@ -1,10 +1,9 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 35
+; Bound: 33
 ; Schema: 0
                OpCapability Shader
-         %15 = OpExtInstImport "GLSL.std.450"
                OpMemoryModel Logical GLSL450
                OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
                OpEntryPoint Fragment %fragment_main "fragment_main"
@@ -32,38 +31,37 @@
        %void = OpTypeVoid
           %9 = OpTypeFunction %void
     %v2float = OpTypeVector %float 2
-       %uint = OpTypeInt 32 0
+%float_1_52590219en05 = OpConstant %float 1.52590219e-05
-     %uint_1 = OpConstant %uint 1
+         %15 = OpConstantComposite %v2float %float_1_52590219en05 %8
 %_ptr_Function_v2float = OpTypePointer Function %v2float
-         %20 = OpConstantNull %v2float
+         %18 = OpConstantNull %v2float
-         %21 = OpTypeFunction %v4float
+         %19 = OpTypeFunction %v4float
     %float_1 = OpConstant %float 1
 %unpack2x16unorm_7699c0 = OpFunction %void None %9
          %12 = OpLabel
-        %res = OpVariable %_ptr_Function_v2float Function %20
+        %res = OpVariable %_ptr_Function_v2float Function %18
-         %13 = OpExtInst %v2float %15 UnpackUnorm2x16 %uint_1
+               OpStore %res %15
-               OpStore %res %13
                OpReturn
                OpFunctionEnd
-%vertex_main_inner = OpFunction %v4float None %21
+%vertex_main_inner = OpFunction %v4float None %19
-         %23 = OpLabel
+         %21 = OpLabel
-         %24 = OpFunctionCall %void %unpack2x16unorm_7699c0
+         %22 = OpFunctionCall %void %unpack2x16unorm_7699c0
                OpReturnValue %5
                OpFunctionEnd
 %vertex_main = OpFunction %void None %9
-         %26 = OpLabel
+         %24 = OpLabel
-         %27 = OpFunctionCall %v4float %vertex_main_inner
+         %25 = OpFunctionCall %v4float %vertex_main_inner
-               OpStore %value %27
+               OpStore %value %25
                OpStore %vertex_point_size %float_1
                OpReturn
                OpFunctionEnd
 %fragment_main = OpFunction %void None %9
-         %30 = OpLabel
+         %28 = OpLabel
-         %31 = OpFunctionCall %void %unpack2x16unorm_7699c0
+         %29 = OpFunctionCall %void %unpack2x16unorm_7699c0
                OpReturn
                OpFunctionEnd
 %compute_main = OpFunction %void None %9
-         %33 = OpLabel
+         %31 = OpLabel
-         %34 = OpFunctionCall %void %unpack2x16unorm_7699c0
+         %32 = OpFunctionCall %void %unpack2x16unorm_7699c0
                OpReturn
                OpFunctionEnd

test/tint/builtins/gen/literal/unpack4x8snorm/523fb3.wgsl.expected.dxc.hlsl

@@ -1,11 +1,5 @@
-float4 tint_unpack4x8snorm(uint param_0) {
-  int j = int(param_0);
-  int4 i = int4(j << 24, j << 16, j << 8, j) >> 24;
-  return clamp(float4(i) / 127.0, -1.0, 1.0);
-}
-
 void unpack4x8snorm_523fb3() {
-  float4 res = tint_unpack4x8snorm(1u);
+  float4 res = float4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8snorm/523fb3.wgsl.expected.fxc.hlsl

@@ -1,11 +1,5 @@
-float4 tint_unpack4x8snorm(uint param_0) {
-  int j = int(param_0);
-  int4 i = int4(j << 24, j << 16, j << 8, j) >> 24;
-  return clamp(float4(i) / 127.0, -1.0, 1.0);
-}
-
 void unpack4x8snorm_523fb3() {
-  float4 res = tint_unpack4x8snorm(1u);
+  float4 res = float4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8snorm/523fb3.wgsl.expected.glsl

@@ -1,7 +1,7 @@
 #version 310 es
 
 void unpack4x8snorm_523fb3() {
-  vec4 res = unpackSnorm4x8(1u);
+  vec4 res = vec4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 vec4 vertex_main() {
@@ -21,7 +21,7 @@ void main() {
 precision mediump float;
 
 void unpack4x8snorm_523fb3() {
-  vec4 res = unpackSnorm4x8(1u);
+  vec4 res = vec4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 void fragment_main() {
@@ -35,7 +35,7 @@ void main() {
 #version 310 es
 
 void unpack4x8snorm_523fb3() {
-  vec4 res = unpackSnorm4x8(1u);
+  vec4 res = vec4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 void compute_main() {

test/tint/builtins/gen/literal/unpack4x8snorm/523fb3.wgsl.expected.msl

@@ -2,7 +2,7 @@
 
 using namespace metal;
 void unpack4x8snorm_523fb3() {
-  float4 res = unpack_snorm4x8_to_float(1u);
+  float4 res = float4(0.007874016f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8snorm/523fb3.wgsl.expected.spvasm

@@ -1,10 +1,9 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 33
+; Bound: 31
 ; Schema: 0
                OpCapability Shader
-         %14 = OpExtInstImport "GLSL.std.450"
                OpMemoryModel Logical GLSL450
                OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
                OpEntryPoint Fragment %fragment_main "fragment_main"
@@ -31,37 +30,36 @@
 %vertex_point_size = OpVariable %_ptr_Output_float Output %8
        %void = OpTypeVoid
           %9 = OpTypeFunction %void
-       %uint = OpTypeInt 32 0
+%float_0_00787401572 = OpConstant %float 0.00787401572
-     %uint_1 = OpConstant %uint 1
+         %14 = OpConstantComposite %v4float %float_0_00787401572 %8 %8 %8
 %_ptr_Function_v4float = OpTypePointer Function %v4float
-         %19 = OpTypeFunction %v4float
+         %17 = OpTypeFunction %v4float
     %float_1 = OpConstant %float 1
 %unpack4x8snorm_523fb3 = OpFunction %void None %9
          %12 = OpLabel
         %res = OpVariable %_ptr_Function_v4float Function %5
-         %13 = OpExtInst %v4float %14 UnpackSnorm4x8 %uint_1
+               OpStore %res %14
-               OpStore %res %13
                OpReturn
                OpFunctionEnd
-%vertex_main_inner = OpFunction %v4float None %19
+%vertex_main_inner = OpFunction %v4float None %17
-         %21 = OpLabel
+         %19 = OpLabel
-         %22 = OpFunctionCall %void %unpack4x8snorm_523fb3
+         %20 = OpFunctionCall %void %unpack4x8snorm_523fb3
                OpReturnValue %5
                OpFunctionEnd
 %vertex_main = OpFunction %void None %9
-         %24 = OpLabel
+         %22 = OpLabel
-         %25 = OpFunctionCall %v4float %vertex_main_inner
+         %23 = OpFunctionCall %v4float %vertex_main_inner
-               OpStore %value %25
+               OpStore %value %23
                OpStore %vertex_point_size %float_1
                OpReturn
                OpFunctionEnd
 %fragment_main = OpFunction %void None %9
-         %28 = OpLabel
+         %26 = OpLabel
-         %29 = OpFunctionCall %void %unpack4x8snorm_523fb3
+         %27 = OpFunctionCall %void %unpack4x8snorm_523fb3
                OpReturn
                OpFunctionEnd
 %compute_main = OpFunction %void None %9
-         %31 = OpLabel
+         %29 = OpLabel
-         %32 = OpFunctionCall %void %unpack4x8snorm_523fb3
+         %30 = OpFunctionCall %void %unpack4x8snorm_523fb3
                OpReturn
                OpFunctionEnd

test/tint/builtins/gen/literal/unpack4x8unorm/750c74.wgsl.expected.dxc.hlsl

@@ -1,11 +1,5 @@
-float4 tint_unpack4x8unorm(uint param_0) {
-  uint j = param_0;
-  uint4 i = uint4(j & 0xff, (j >> 8) & 0xff, (j >> 16) & 0xff, j >> 24);
-  return float4(i) / 255.0;
-}
-
 void unpack4x8unorm_750c74() {
-  float4 res = tint_unpack4x8unorm(1u);
+  float4 res = float4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8unorm/750c74.wgsl.expected.fxc.hlsl

@@ -1,11 +1,5 @@
-float4 tint_unpack4x8unorm(uint param_0) {
-  uint j = param_0;
-  uint4 i = uint4(j & 0xff, (j >> 8) & 0xff, (j >> 16) & 0xff, j >> 24);
-  return float4(i) / 255.0;
-}
-
 void unpack4x8unorm_750c74() {
-  float4 res = tint_unpack4x8unorm(1u);
+  float4 res = float4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8unorm/750c74.wgsl.expected.glsl

@@ -1,7 +1,7 @@
 #version 310 es
 
 void unpack4x8unorm_750c74() {
-  vec4 res = unpackUnorm4x8(1u);
+  vec4 res = vec4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 vec4 vertex_main() {
@@ -21,7 +21,7 @@ void main() {
 precision mediump float;
 
 void unpack4x8unorm_750c74() {
-  vec4 res = unpackUnorm4x8(1u);
+  vec4 res = vec4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 void fragment_main() {
@@ -35,7 +35,7 @@ void main() {
 #version 310 es
 
 void unpack4x8unorm_750c74() {
-  vec4 res = unpackUnorm4x8(1u);
+  vec4 res = vec4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 void compute_main() {

test/tint/builtins/gen/literal/unpack4x8unorm/750c74.wgsl.expected.msl

@@ -2,7 +2,7 @@
 
 using namespace metal;
 void unpack4x8unorm_750c74() {
-  float4 res = unpack_unorm4x8_to_float(1u);
+  float4 res = float4(0.003921569f, 0.0f, 0.0f, 0.0f);
 }
 
 struct tint_symbol {

test/tint/builtins/gen/literal/unpack4x8unorm/750c74.wgsl.expected.spvasm

@@ -1,10 +1,9 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 33
+; Bound: 31
 ; Schema: 0
                OpCapability Shader
-         %14 = OpExtInstImport "GLSL.std.450"
                OpMemoryModel Logical GLSL450
                OpEntryPoint Vertex %vertex_main "vertex_main" %value %vertex_point_size
                OpEntryPoint Fragment %fragment_main "fragment_main"
@@ -31,37 +30,36 @@
 %vertex_point_size = OpVariable %_ptr_Output_float Output %8
        %void = OpTypeVoid
           %9 = OpTypeFunction %void
-       %uint = OpTypeInt 32 0
+%float_0_00392156886 = OpConstant %float 0.00392156886
-     %uint_1 = OpConstant %uint 1
+         %14 = OpConstantComposite %v4float %float_0_00392156886 %8 %8 %8
 %_ptr_Function_v4float = OpTypePointer Function %v4float
-         %19 = OpTypeFunction %v4float
+         %17 = OpTypeFunction %v4float
     %float_1 = OpConstant %float 1
 %unpack4x8unorm_750c74 = OpFunction %void None %9
          %12 = OpLabel
         %res = OpVariable %_ptr_Function_v4float Function %5
-         %13 = OpExtInst %v4float %14 UnpackUnorm4x8 %uint_1
+               OpStore %res %14
-               OpStore %res %13
                OpReturn
                OpFunctionEnd
-%vertex_main_inner = OpFunction %v4float None %19
+%vertex_main_inner = OpFunction %v4float None %17
-         %21 = OpLabel
+         %19 = OpLabel
-         %22 = OpFunctionCall %void %unpack4x8unorm_750c74
+         %20 = OpFunctionCall %void %unpack4x8unorm_750c74
                OpReturnValue %5
                OpFunctionEnd
 %vertex_main = OpFunction %void None %9
-         %24 = OpLabel
+         %22 = OpLabel
-         %25 = OpFunctionCall %v4float %vertex_main_inner
+         %23 = OpFunctionCall %v4float %vertex_main_inner
-               OpStore %value %25
+               OpStore %value %23
                OpStore %vertex_point_size %float_1
                OpReturn
                OpFunctionEnd
 %fragment_main = OpFunction %void None %9
-         %28 = OpLabel
+         %26 = OpLabel
-         %29 = OpFunctionCall %void %unpack4x8unorm_750c74
+         %27 = OpFunctionCall %void %unpack4x8unorm_750c74
                OpReturn
                OpFunctionEnd
 %compute_main = OpFunction %void None %9
-         %31 = OpLabel
+         %29 = OpLabel
-         %32 = OpFunctionCall %void %unpack4x8unorm_750c74
+         %30 = OpFunctionCall %void %unpack4x8unorm_750c74
                OpReturn
                OpFunctionEnd