GLSL: implement fma().

Bug: tint:1448
Change-Id: I7e331a2eabd507a4babce756fc79d68b0bf7d7be
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/82145
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>

src/tint/writer/glsl/generator_impl.cc

@@ -610,6 +610,9 @@ bool GeneratorImpl::EmitBuiltinCall(std::ostream& out,
   if (builtin->Type() == sem::BuiltinType::kInsertBits) {
     return EmitInsertBits(out, expr);
   }
+  if (builtin->Type() == sem::BuiltinType::kFma && version_.IsES()) {
+    return EmitEmulatedFMA(out, expr);
+  }
   if (builtin->IsDataPacking()) {
     return EmitDataPackingCall(out, expr, builtin);
   }
@@ -859,6 +862,24 @@ bool GeneratorImpl::EmitInsertBits(std::ostream& out,
   return true;
 }
 
+bool GeneratorImpl::EmitEmulatedFMA(std::ostream& out,
+                                    const ast::CallExpression* expr) {
+  out << "((";
+  if (!EmitExpression(out, expr->args[0])) {
+    return false;
+  }
+  out << ") * (";
+  if (!EmitExpression(out, expr->args[1])) {
+    return false;
+  }
+  out << ") + (";
+  if (!EmitExpression(out, expr->args[2])) {
+    return false;
+  }
+  out << "))";
+  return true;
+}
+
 bool GeneratorImpl::EmitSelectCall(std::ostream& out,
                                    const ast::CallExpression* expr) {
   auto* expr_false = expr->args[0];
@@ -1619,7 +1640,7 @@ std::string GeneratorImpl::generate_builtin_name(const sem::Builtin* builtin) {
     case sem::BuiltinType::kFract:
       return "fract";
     case sem::BuiltinType::kFma:
-      return "mad";
+      return "fma";
     case sem::BuiltinType::kFwidth:
     case sem::BuiltinType::kFwidthCoarse:
     case sem::BuiltinType::kFwidthFine:

src/tint/writer/glsl/generator_impl.h

@@ -181,6 +181,11 @@ class GeneratorImpl : public TextGenerator {
   /// @param expr the call expression
   /// @returns true if the expression is emitted
   bool EmitInsertBits(std::ostream& out, const ast::CallExpression* expr);
+  /// Emulates 'fma' on GLSL ES, where it is unsupported.
+  /// @param out the output of the expression stream
+  /// @param expr the fma() expression
+  /// @returns true if the expression is emitted
+  bool EmitEmulatedFMA(std::ostream& out, const ast::CallExpression* expr);
   /// Handles generating a call to a texture function (`textureSample`,
   /// `textureSampleGrad`, etc)
   /// @param out the output of the expression stream

src/tint/writer/glsl/generator_impl_builtin_test.cc

@@ -213,7 +213,7 @@ INSTANTIATE_TEST_SUITE_P(
         BuiltinData{BuiltinType::kExp2, ParamType::kF32, "exp2"},
         BuiltinData{BuiltinType::kFaceForward, ParamType::kF32, "faceforward"},
         BuiltinData{BuiltinType::kFloor, ParamType::kF32, "floor"},
-        BuiltinData{BuiltinType::kFma, ParamType::kF32, "mad"},
+        BuiltinData{BuiltinType::kFma, ParamType::kF32, "fma"},
         BuiltinData{BuiltinType::kFract, ParamType::kF32, "fract"},
         BuiltinData{BuiltinType::kFwidth, ParamType::kF32, "fwidth"},
         BuiltinData{BuiltinType::kFwidthCoarse, ParamType::kF32, "fwidth"},
@@ -873,6 +873,23 @@ void main() {
 )");
 }
 
+TEST_F(GlslGeneratorImplTest_Builtin, FMA) {
+  auto* call = Call("fma", "a", "b", "c");
+
+  Global("a", ty.vec3<f32>(), ast::StorageClass::kPrivate);
+  Global("b", ty.vec3<f32>(), ast::StorageClass::kPrivate);
+  Global("c", ty.vec3<f32>(), ast::StorageClass::kPrivate);
+
+  WrapInFunction(CallStmt(call));
+
+  GeneratorImpl& gen = Build();
+
+  gen.increment_indent();
+  std::stringstream out;
+  ASSERT_TRUE(gen.EmitExpression(out, call)) << gen.error();
+  EXPECT_EQ(out.str(), "((a) * (b) + (c))");
+}
+
 TEST_F(GlslGeneratorImplTest_Builtin, DotU32) {
   Global("v", ty.vec3<u32>(), ast::StorageClass::kPrivate);
   WrapInFunction(CallStmt(Call("dot", "v", "v")));

src/tint/writer/glsl/generator_impl_import_test.cc

@@ -212,8 +212,7 @@ TEST_P(GlslImportData_TripleParam_ScalarTest, Float) {
 }
 INSTANTIATE_TEST_SUITE_P(GlslGeneratorImplTest_Import,
                          GlslImportData_TripleParam_ScalarTest,
-                         testing::Values(GlslImportData{"fma", "mad"},
+                         testing::Values(GlslImportData{"mix", "mix"},
-                                         GlslImportData{"mix", "mix"},
                                          GlslImportData{"clamp", "clamp"},
                                          GlslImportData{"smoothStep",
                                                         "smoothstep"}));
@@ -239,7 +238,6 @@ INSTANTIATE_TEST_SUITE_P(
     GlslGeneratorImplTest_Import,
     GlslImportData_TripleParam_VectorTest,
     testing::Values(GlslImportData{"faceForward", "faceforward"},
-                    GlslImportData{"fma", "mad"},
                     GlslImportData{"clamp", "clamp"},
                     GlslImportData{"smoothStep", "smoothstep"}));
 

test/tint/benchmark/skinned-shadowed-pbr-fragment.wgsl.expected.glsl

@@ -1,5 +1,3 @@
-SKIP: FAILED
-
 benchmark/skinned-shadowed-pbr-fragment.wgsl:51:13 warning: use of deprecated language feature: the @stride attribute is deprecated; use a larger type if necessary
   lights : @stride(32) array<Light>;
             ^^^^^^
@@ -79,7 +77,7 @@ layout(binding = 2, std430) buffer GlobalLights_1 {
 } globalLights;
 const uvec3 tileCount = uvec3(32u, 18u, 48u);
 float linearDepth(float depthSample) {
-  return ((camera.zFar * camera.zNear) / mad(depthSample, (camera.zNear - camera.zFar), camera.zFar));
+  return ((camera.zFar * camera.zNear) / ((depthSample) * ((camera.zNear - camera.zFar)) + (camera.zFar)));
 }
 
 uvec3 getTile(vec4 fragCoord) {
@@ -370,10 +368,3 @@ void main() {
   emissive_1 = inner_result.emissive;
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:76: 'mad' : no matching overloaded function found 
-ERROR: 0:76: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-

test/tint/builtins/gen/fma/26a7a9.wgsl.expected.glsl

@@ -1,9 +1,7 @@
-SKIP: FAILED
-
 #version 310 es
 
 void fma_26a7a9() {
-  vec2 res = mad(vec2(0.0f, 0.0f), vec2(0.0f, 0.0f), vec2(0.0f, 0.0f));
+  vec2 res = ((vec2(0.0f, 0.0f)) * (vec2(0.0f, 0.0f)) + (vec2(0.0f, 0.0f)));
 }
 
 vec4 vertex_main() {
@@ -18,19 +16,11 @@ void main() {
   gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 2-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 precision mediump float;
 
 void fma_26a7a9() {
-  vec2 res = mad(vec2(0.0f, 0.0f), vec2(0.0f, 0.0f), vec2(0.0f, 0.0f));
+  vec2 res = ((vec2(0.0f, 0.0f)) * (vec2(0.0f, 0.0f)) + (vec2(0.0f, 0.0f)));
 }
 
 void fragment_main() {
@@ -41,18 +31,10 @@ void main() {
   fragment_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:5: 'mad' : no matching overloaded function found 
-ERROR: 0:5: '=' :  cannot convert from ' const float' to ' temp mediump 2-component vector of float'
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 
 void fma_26a7a9() {
-  vec2 res = mad(vec2(0.0f, 0.0f), vec2(0.0f, 0.0f), vec2(0.0f, 0.0f));
+  vec2 res = ((vec2(0.0f, 0.0f)) * (vec2(0.0f, 0.0f)) + (vec2(0.0f, 0.0f)));
 }
 
 void compute_main() {
@@ -64,11 +46,3 @@ void main() {
   compute_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 2-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/builtins/gen/fma/6a3283.wgsl.expected.glsl

@@ -1,9 +1,7 @@
-SKIP: FAILED
-
 #version 310 es
 
 void fma_6a3283() {
-  vec4 res = mad(vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f));
+  vec4 res = ((vec4(0.0f, 0.0f, 0.0f, 0.0f)) * (vec4(0.0f, 0.0f, 0.0f, 0.0f)) + (vec4(0.0f, 0.0f, 0.0f, 0.0f)));
 }
 
 vec4 vertex_main() {
@@ -18,19 +16,11 @@ void main() {
   gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 4-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 precision mediump float;
 
 void fma_6a3283() {
-  vec4 res = mad(vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f));
+  vec4 res = ((vec4(0.0f, 0.0f, 0.0f, 0.0f)) * (vec4(0.0f, 0.0f, 0.0f, 0.0f)) + (vec4(0.0f, 0.0f, 0.0f, 0.0f)));
 }
 
 void fragment_main() {
@@ -41,18 +31,10 @@ void main() {
   fragment_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:5: 'mad' : no matching overloaded function found 
-ERROR: 0:5: '=' :  cannot convert from ' const float' to ' temp mediump 4-component vector of float'
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 
 void fma_6a3283() {
-  vec4 res = mad(vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f), vec4(0.0f, 0.0f, 0.0f, 0.0f));
+  vec4 res = ((vec4(0.0f, 0.0f, 0.0f, 0.0f)) * (vec4(0.0f, 0.0f, 0.0f, 0.0f)) + (vec4(0.0f, 0.0f, 0.0f, 0.0f)));
 }
 
 void compute_main() {
@@ -64,11 +46,3 @@ void main() {
   compute_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 4-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/builtins/gen/fma/c10ba3.wgsl.expected.glsl

@@ -1,9 +1,7 @@
-SKIP: FAILED
-
 #version 310 es
 
 void fma_c10ba3() {
-  float res = mad(1.0f, 1.0f, 1.0f);
+  float res = ((1.0f) * (1.0f) + (1.0f));
 }
 
 vec4 vertex_main() {
@@ -18,18 +16,11 @@ void main() {
   gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-
 #version 310 es
 precision mediump float;
 
 void fma_c10ba3() {
-  float res = mad(1.0f, 1.0f, 1.0f);
+  float res = ((1.0f) * (1.0f) + (1.0f));
 }
 
 void fragment_main() {
@@ -40,17 +31,10 @@ void main() {
   fragment_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:5: 'mad' : no matching overloaded function found 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-
 #version 310 es
 
 void fma_c10ba3() {
-  float res = mad(1.0f, 1.0f, 1.0f);
+  float res = ((1.0f) * (1.0f) + (1.0f));
 }
 
 void compute_main() {
@@ -62,10 +46,3 @@ void main() {
   compute_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-

test/tint/builtins/gen/fma/e17c5c.wgsl.expected.glsl

@@ -1,9 +1,7 @@
-SKIP: FAILED
-
 #version 310 es
 
 void fma_e17c5c() {
-  vec3 res = mad(vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f));
+  vec3 res = ((vec3(0.0f, 0.0f, 0.0f)) * (vec3(0.0f, 0.0f, 0.0f)) + (vec3(0.0f, 0.0f, 0.0f)));
 }
 
 vec4 vertex_main() {
@@ -18,19 +16,11 @@ void main() {
   gl_Position.z = ((2.0f * gl_Position.z) - gl_Position.w);
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 3-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 precision mediump float;
 
 void fma_e17c5c() {
-  vec3 res = mad(vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f));
+  vec3 res = ((vec3(0.0f, 0.0f, 0.0f)) * (vec3(0.0f, 0.0f, 0.0f)) + (vec3(0.0f, 0.0f, 0.0f)));
 }
 
 void fragment_main() {
@@ -41,18 +31,10 @@ void main() {
   fragment_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:5: 'mad' : no matching overloaded function found 
-ERROR: 0:5: '=' :  cannot convert from ' const float' to ' temp mediump 3-component vector of float'
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-
 #version 310 es
 
 void fma_e17c5c() {
-  vec3 res = mad(vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f), vec3(0.0f, 0.0f, 0.0f));
+  vec3 res = ((vec3(0.0f, 0.0f, 0.0f)) * (vec3(0.0f, 0.0f, 0.0f)) + (vec3(0.0f, 0.0f, 0.0f)));
 }
 
 void compute_main() {
@@ -64,11 +46,3 @@ void main() {
   compute_main();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: 'mad' : no matching overloaded function found 
-ERROR: 0:4: '=' :  cannot convert from ' const float' to ' temp highp 3-component vector of float'
-ERROR: 0:4: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/builtins/gen/textureDimensions/ba1481.wgsl.expected.glsl

@@ -1,6 +1,6 @@
 SKIP: FAILED
 
-../../src/tint/writer/glsl/generator_impl.cc:2576 internal compiler error: Multiplanar external texture transform was not run.
+../../src/tint/writer/glsl/generator_impl.cc:2589 internal compiler error: Multiplanar external texture transform was not run.
 
 
 ********************************************************************

test/tint/builtins/gen/textureLoad/8acf41.wgsl.expected.glsl

@@ -1,6 +1,6 @@
 SKIP: FAILED
 
-../../src/tint/writer/glsl/generator_impl.cc:2576 internal compiler error: Multiplanar external texture transform was not run.
+../../src/tint/writer/glsl/generator_impl.cc:2589 internal compiler error: Multiplanar external texture transform was not run.
 
 
 ********************************************************************

test/tint/builtins/gen/textureSampleLevel/979816.wgsl.expected.glsl

@@ -1,6 +1,6 @@
 SKIP: FAILED
 
-../../src/tint/writer/glsl/generator_impl.cc:2576 internal compiler error: Multiplanar external texture transform was not run.
+../../src/tint/writer/glsl/generator_impl.cc:2589 internal compiler error: Multiplanar external texture transform was not run.
 
 
 ********************************************************************

test/tint/unittest/reader/spirv/Samples_SpvParserTest_GlslStd450_Floating_FloatingFloatingFloating_Scalar_2.spvasm.expected.glsl

@@ -1,5 +1,3 @@
-SKIP: FAILED
-
 #version 310 es
 
 void main_1() {
@@ -25,7 +23,7 @@ void main_1() {
   vec3 v3f2 = vec3(60.0f, 70.0f, 50.0f);
   vec4 v4f1 = vec4(50.0f, 50.0f, 50.0f, 50.0f);
   vec4 v4f2 = v4f1;
-  float x_1 = mad(f1, f2, f3);
+  float x_1 = ((f1) * (f2) + (f3));
   return;
 }
 
@@ -38,10 +36,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:26: 'mad' : no matching overloaded function found 
-ERROR: 0:26: '' : compilation terminated 
-ERROR: 2 compilation errors.  No code generated.
-
-
-

test/tint/unittest/reader/spirv/Samples_SpvParserTest_GlslStd450_Floating_FloatingFloatingFloating_Vector_2.spvasm.expected.glsl

@@ -1,5 +1,3 @@
-SKIP: FAILED
-
 #version 310 es
 
 void main_1() {
@@ -25,7 +23,7 @@ void main_1() {
   vec3 v3f2 = vec3(60.0f, 70.0f, 50.0f);
   vec4 v4f1 = vec4(50.0f, 50.0f, 50.0f, 50.0f);
   vec4 v4f2 = v4f1;
-  vec2 x_1 = mad(v2f1, v2f2, v2f3);
+  vec2 x_1 = ((v2f1) * (v2f2) + (v2f3));
   return;
 }
 
@@ -38,11 +36,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:26: 'mad' : no matching overloaded function found 
-ERROR: 0:26: '=' :  cannot convert from ' const float' to ' temp highp 2-component vector of float'
-ERROR: 0:26: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-