tint: Implement signed-int overloads of sign()

Bug: tint:1581
Fixed: tint:1782
Change-Id: Ia029bf9d1ce1d978c5cabc3016cb8ad1b4bac06a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/113243
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/transform/builtin_polyfill.cc

@@ -590,6 +590,32 @@ struct BuiltinPolyfill::State {
         return name;
     }
 
+    /// Builds the polyfill function for the `sign` builtin when the element type is integer
+    /// @param ty the parameter and return type for the function
+    /// @return the polyfill function name
+    Symbol sign_int(const sem::Type* ty) {
+        const uint32_t width = WidthOf(ty);
+        auto zero = [&] { return ScalarOrVector(width, 0_a); };
+
+        // pos_or_neg_one = (v > 0) ? 1 : -1
+        auto pos_or_neg_one = b.Call("select",                     //
+                                     ScalarOrVector(width, -1_a),  //
+                                     ScalarOrVector(width, 1_a),   //
+                                     b.GreaterThan("v", zero()));
+
+        auto name = b.Symbols().New("tint_sign");
+        b.Func(name,
+               utils::Vector{
+                   b.Param("v", T(ty)),
+               },
+               T(ty),
+               utils::Vector{
+                   b.Return(b.Call("select", pos_or_neg_one, zero(), b.Equal("v", zero()))),
+               });
+
+        return name;
+    }
+
     /// Builds the polyfill function for the `textureSampleBaseClampToEdge` builtin, when the
     /// texture type is texture_2d<f32>.
     /// @return the polyfill function name
@@ -855,6 +881,15 @@ Transform::ApplyResult BuiltinPolyfill::Apply(const Program* src,
                             builtin, [&] { return s.saturate(builtin->ReturnType()); });
                     }
                     break;
+                case sem::BuiltinType::kSign:
+                    if (polyfill.sign_int) {
+                        auto* ty = builtin->ReturnType();
+                        if (ty->is_signed_integer_scalar_or_vector()) {
+                            fn = builtin_polyfills.GetOrCreate(builtin,
+                                                               [&] { return s.sign_int(ty); });
+                        }
+                    }
+                    break;
                 case sem::BuiltinType::kTextureSampleBaseClampToEdge:
                     if (polyfill.texture_sample_base_clamp_to_edge_2d_f32) {
                         auto& sig = builtin->Signature();

src/tint/transform/builtin_polyfill.h

@@ -68,6 +68,8 @@ class BuiltinPolyfill final : public Castable<BuiltinPolyfill, Transform> {
         bool int_div_mod = false;
         /// Should `saturate()` be polyfilled?
         bool saturate = false;
+        /// Should `sign()` be polyfilled for integer types?
+        bool sign_int = false;
         /// Should `textureSampleBaseClampToEdge()` be polyfilled for texture_2d<f32> textures?
         bool texture_sample_base_clamp_to_edge_2d_f32 = false;
         /// Should the vector form of `quantizeToF16()` be polyfilled with a scalar implementation?

src/tint/transform/builtin_polyfill_test.cc

@@ -34,11 +34,7 @@ TEST_F(BuiltinPolyfillTest, ShouldRunEmptyModule) {
 TEST_F(BuiltinPolyfillTest, EmptyModule) {
     auto* src = R"()";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src);
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -73,11 +69,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillAcosh(Level::kFull));
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillAcosh(Level::kFull)));
 }
 
 TEST_F(BuiltinPolyfillTest, Acosh_Full_f32) {
@@ -206,11 +198,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillSinh());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillSinh()));
 }
 
 TEST_F(BuiltinPolyfillTest, Asinh_f32) {
@@ -293,11 +281,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillAtanh(Level::kFull));
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillAtanh(Level::kFull)));
 }
 
 TEST_F(BuiltinPolyfillTest, Atanh_Full_f32) {
@@ -603,11 +587,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillClampInteger());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillClampInteger()));
 }
 
 TEST_F(BuiltinPolyfillTest, ClampInteger_i32) {
@@ -732,11 +712,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillCountLeadingZeros());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillCountLeadingZeros()));
 }
 
 TEST_F(BuiltinPolyfillTest, CountLeadingZeros_i32) {
@@ -909,11 +885,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillCountTrailingZeros());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillCountTrailingZeros()));
 }
 
 TEST_F(BuiltinPolyfillTest, CountTrailingZeros_i32) {
@@ -1088,11 +1060,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillExtractBits(Level::kFull));
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillExtractBits(Level::kFull)));
 }
 
 TEST_F(BuiltinPolyfillTest, ExtractBits_Full_i32) {
@@ -1345,11 +1313,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillFirstLeadingBit());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillFirstLeadingBit()));
 }
 
 TEST_F(BuiltinPolyfillTest, FirstLeadingBit_i32) {
@@ -1522,11 +1486,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillFirstTrailingBit());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillFirstTrailingBit()));
 }
 
 TEST_F(BuiltinPolyfillTest, FirstTrailingBit_i32) {
@@ -1701,11 +1661,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillInsertBits(Level::kFull));
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillInsertBits(Level::kFull)));
 }
 
 TEST_F(BuiltinPolyfillTest, InsertBits_Full_i32) {
@@ -2715,11 +2671,7 @@ fn f() {
 }
 )";
 
-    auto* expect = src;
-
-    auto got = Run<BuiltinPolyfill>(src, polyfillSaturate());
-
-    EXPECT_EQ(expect, str(got));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillSaturate()));
 }
 
 TEST_F(BuiltinPolyfillTest, Saturate_f32) {
@@ -2826,6 +2778,99 @@ fn f() {
     EXPECT_EQ(expect, str(got));
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// sign_int
+////////////////////////////////////////////////////////////////////////////////
+DataMap polyfillSignInt() {
+    BuiltinPolyfill::Builtins builtins;
+    builtins.sign_int = true;
+    DataMap data;
+    data.Add<BuiltinPolyfill::Config>(builtins);
+    return data;
+}
+
+TEST_F(BuiltinPolyfillTest, ShouldRunSign_i32) {
+    auto* src = R"(
+fn f() {
+  let v = 1i;
+  sign(v);
+}
+)";
+
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src));
+    EXPECT_TRUE(ShouldRun<BuiltinPolyfill>(src, polyfillSignInt()));
+}
+
+TEST_F(BuiltinPolyfillTest, ShouldRunSign_f32) {
+    auto* src = R"(
+fn f() {
+  let v = 1f;
+  sign(v);
+}
+)";
+
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src));
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillSignInt()));
+}
+
+TEST_F(BuiltinPolyfillTest, SignInt_ConstantExpression) {
+    auto* src = R"(
+fn f() {
+  let r : i32 = sign(1i);
+}
+)";
+
+    EXPECT_FALSE(ShouldRun<BuiltinPolyfill>(src, polyfillSignInt()));
+}
+
+TEST_F(BuiltinPolyfillTest, SignInt_i32) {
+    auto* src = R"(
+fn f() {
+  let v = 1i;
+  let r : i32 = sign(v);
+}
+)";
+
+    auto* expect = R"(
+fn tint_sign(v : i32) -> i32 {
+  return select(select(-1, 1, (v > 0)), 0, (v == 0));
+}
+
+fn f() {
+  let v = 1i;
+  let r : i32 = tint_sign(v);
+}
+)";
+
+    auto got = Run<BuiltinPolyfill>(src, polyfillSignInt());
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(BuiltinPolyfillTest, SignInt_vec3_i32) {
+    auto* src = R"(
+fn f() {
+  let v = 1i;
+  let r : vec3<i32> = sign(vec3<i32>(v));
+}
+)";
+
+    auto* expect = R"(
+fn tint_sign(v : vec3<i32>) -> vec3<i32> {
+  return select(select(vec3(-1), vec3(1), (v > vec3(0))), vec3(0), (v == vec3(0)));
+}
+
+fn f() {
+  let v = 1i;
+  let r : vec3<i32> = tint_sign(vec3<i32>(v));
+}
+)";
+
+    auto got = Run<BuiltinPolyfill>(src, polyfillSignInt());
+
+    EXPECT_EQ(expect, str(got));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // textureSampleBaseClampToEdge
 ////////////////////////////////////////////////////////////////////////////////