[HLSL] Remove faceforward SPIRV fast path

[kmpeng]

Follow up to PR #139959.

Tasks completed:

• Remove the faceforward SPIRV fast path because the pattern matching added in #139959 transforms select(dot(I, Ng) < 0, N, -N) into faceforward at the backend level
• Update the faceforward.hlsl test accordingly

[llvmbot]

@llvm/pr-subscribers-hlsl
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-backend-x86

Author: Kaitlin Peng (kmpeng)

Changes

Follow up to PR #139959.

Tasks completed:

• Remove the faceforward SPIRV fast path because the pattern matching added in #139959 transforms select(dot(I, Ng) < 0, N, -N) into faceforward at the backend level
• Update the faceforward.hlsl test accordingly

---

Full diff: https://github.com/llvm/llvm-project/pull/169547.diff

2 Files Affected:

• (modified) clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h (-4)
• (modified) clang/test/CodeGenHLSL/builtins/faceforward.hlsl (+9-32)

diff --git a/clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h b/clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h
index d1dc8275431c0..3550409b6988d 100644
--- a/clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h
@@ -137,11 +137,7 @@ template <typename T> constexpr vector<T, 4> lit_impl(T NDotL, T NDotH, T M) {
 }
 
 template <typename T> constexpr T faceforward_impl(T N, T I, T Ng) {
-#if (__has_builtin(__builtin_spirv_faceforward))
-  return __builtin_spirv_faceforward(N, I, Ng);
-#else
   return select(dot(I, Ng) < 0, N, -N);
-#endif
 }
 
 template <typename T> constexpr T ldexp_impl(T X, T Exp) {
diff --git a/clang/test/CodeGenHLSL/builtins/faceforward.hlsl b/clang/test/CodeGenHLSL/builtins/faceforward.hlsl
index 70459d81685a1..261454e8bc152 100644
--- a/clang/test/CodeGenHLSL/builtins/faceforward.hlsl
+++ b/clang/test/CodeGenHLSL/builtins/faceforward.hlsl
@@ -1,9 +1,9 @@
 // RUN: %clang_cc1 -finclude-default-header -triple \
 // RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type -fnative-int16-type \
-// RUN:   -emit-llvm -o - | FileCheck %s
+// RUN:   -emit-llvm -o - | FileCheck %s --check-prefixes=CHECK,DXCHECK
 // RUN: %clang_cc1 -finclude-default-header -triple \
 // RUN:   spirv-unknown-vulkan-compute %s -fnative-half-type -fnative-int16-type \
-// RUN:   -emit-llvm -o - | FileCheck %s --check-prefix=SPVCHECK
+// RUN:   -emit-llvm -o - | FileCheck %s --check-prefixes=CHECK,SPVCHECK
 
 // CHECK-LABEL: test_faceforward_half
 // CHECK: %hlsl.dot.i = fmul reassoc nnan ninf nsz arcp afn half %{{.*}}, %{{.*}}
@@ -11,42 +11,31 @@
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn half %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, half %{{.*}}, half %fneg.i
 // CHECK: ret half %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_half
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef half @llvm.spv.faceforward.f16(half %{{.*}}, half %{{.*}}, half %{{.*}})
-// SPVCHECK: ret half %spv.faceforward.i
 half test_faceforward_half(half N, half I, half Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_half2
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.dx.fdot.v2f16(<2 x half> %{{.*}}, <2 x half> %{{.*}})
+// DXCHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.[[ICF:dx]].fdot.v2f16(<2 x half> %{{.*}}, <2 x half> %{{.*}})
+// SPVCHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.[[ICF:spv]].fdot.v2f16(<2 x half> %{{.*}}, <2 x half> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt half %hlsl.dot.i, 0xH0000
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <2 x half> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <2 x half> %{{.*}}, <2 x half> %fneg.i
 // CHECK: ret <2 x half> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_half2
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <2 x half> @llvm.spv.faceforward.v2f16(<2 x half> %{{.*}}, <2 x half> %{{.*}}, <2 x half> %{{.*}})
-// SPVCHECK: ret <2 x half> %spv.faceforward.i
 half2 test_faceforward_half2(half2 N, half2 I, half2 Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_half3
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.dx.fdot.v3f16(<3 x half> %{{.*}}, <3 x half> %{{.*}})
+// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.[[ICF]].fdot.v3f16(<3 x half> %{{.*}}, <3 x half> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt half %hlsl.dot.i, 0xH0000
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <3 x half> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <3 x half> %{{.*}}, <3 x half> %fneg.i
 // CHECK: ret <3 x half> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_half3
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <3 x half> @llvm.spv.faceforward.v3f16(<3 x half> %{{.*}}, <3 x half> %{{.*}}, <3 x half> %{{.*}})
-// SPVCHECK: ret <3 x half> %spv.faceforward.i
 half3 test_faceforward_half3(half3 N, half3 I, half3 Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_half4
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.dx.fdot.v4f16(<4 x half> %{{.*}}, <4 x half> %{{.*}})
+// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn half @llvm.[[ICF]].fdot.v4f16(<4 x half> %{{.*}}, <4 x half> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt half %hlsl.dot.i, 0xH0000
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <4 x half> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <4 x half> %{{.*}}, <4 x half> %fneg.i
 // CHECK: ret <4 x half> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_half4
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <4 x half> @llvm.spv.faceforward.v4f16(<4 x half> %{{.*}}, <4 x half> %{{.*}}, <4 x half> %{{.*}})
-// SPVCHECK: ret <4 x half> %spv.faceforward.i
 half4 test_faceforward_half4(half4 N, half4 I, half4 Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_float
@@ -55,40 +44,28 @@ half4 test_faceforward_half4(half4 N, half4 I, half4 Ng) { return faceforward(N,
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn float %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, float %{{.*}}, float %fneg.i
 // CHECK: ret float %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_float
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef float @llvm.spv.faceforward.f32(float %{{.*}}, float %{{.*}}, float %{{.*}})
-// SPVCHECK: ret float %spv.faceforward.i
 float test_faceforward_float(float N, float I, float Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_float2
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.dx.fdot.v2f32(<2 x float> %{{.*}}, <2 x float> %{{.*}})
+// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.[[ICF]].fdot.v2f32(<2 x float> %{{.*}}, <2 x float> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt float %hlsl.dot.i, 0.000000e+00
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <2 x float> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <2 x float> %{{.*}}, <2 x float> %fneg.i
 // CHECK: ret <2 x float> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_float2
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <2 x float> @llvm.spv.faceforward.v2f32(<2 x float> %{{.*}}, <2 x float> %{{.*}}, <2 x float> %{{.*}})
-// SPVCHECK: ret <2 x float> %spv.faceforward.i
 float2 test_faceforward_float2(float2 N, float2 I, float2 Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_float3
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.dx.fdot.v3f32(<3 x float> %{{.*}}, <3 x float> %{{.*}})
+// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.[[ICF]].fdot.v3f32(<3 x float> %{{.*}}, <3 x float> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt float %hlsl.dot.i, 0.000000e+00
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <3 x float> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <3 x float> %{{.*}}, <3 x float> %fneg.i
 // CHECK: ret <3 x float> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_float3
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <3 x float> @llvm.spv.faceforward.v3f32(<3 x float> %{{.*}}, <3 x float> %{{.*}}, <3 x float> %{{.*}})
-// SPVCHECK: ret <3 x float> %spv.faceforward.i
 float3 test_faceforward_float3(float3 N, float3 I, float3 Ng) { return faceforward(N, I, Ng); }
 
 // CHECK-LABEL: test_faceforward_float4
-// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.dx.fdot.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}})
+// CHECK: %hlsl.dot.i = call reassoc nnan ninf nsz arcp afn float @llvm.[[ICF]].fdot.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}})
 // CHECK: %cmp.i = fcmp reassoc nnan ninf nsz arcp afn olt float %hlsl.dot.i, 0.000000e+00
 // CHECK: %fneg.i = fneg reassoc nnan ninf nsz arcp afn <4 x float> %{{.*}}
 // CHECK: %hlsl.select.i = select reassoc nnan ninf nsz arcp afn i1 %cmp.i, <4 x float> %{{.*}}, <4 x float> %fneg.i
 // CHECK: ret <4 x float> %hlsl.select.i
-// SPVCHECK-LABEL: test_faceforward_float4
-// SPVCHECK: %spv.faceforward.i = call reassoc nnan ninf nsz arcp afn noundef <4 x float> @llvm.spv.faceforward.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}}, <4 x float> %{{.*}})
-// SPVCHECK: ret <4 x float> %spv.faceforward.i
 float4 test_faceforward_float4(float4 N, float4 I, float4 Ng) { return faceforward(N, I, Ng); }

[farzonl]

LGTM