[HLSL] Implement the faceforward intrinsic

clang/include/clang/Basic/BuiltinsSPIRV.td

@@ -31,3 +31,9 @@ def SPIRVSmoothStep : Builtin {
   let Attributes = [NoThrow, Const, CustomTypeChecking];
   let Prototype = "void(...)";
 }
+
+def SPIRVFaceForward : Builtin {
+  let Spellings = ["__builtin_spirv_faceforward"];
+  let Attributes = [NoThrow, Const, CustomTypeChecking];
+  let Prototype = "void(...)";
+}

clang/lib/CodeGen/TargetBuiltins/SPIR.cpp

@@ -71,6 +71,18 @@ Value *CodeGenFunction::EmitSPIRVBuiltinExpr(unsigned BuiltinID,
         ArrayRef<Value *>{Min, Max, X}, /*FMFSource=*/nullptr,
         "spv.smoothstep");
   }
+  case SPIRV::BI__builtin_spirv_faceforward: {
+    Value *N = EmitScalarExpr(E->getArg(0));
+    Value *I = EmitScalarExpr(E->getArg(1));
+    Value *Ng = EmitScalarExpr(E->getArg(2));
+    assert(E->getArg(0)->getType()->hasFloatingRepresentation() &&
+           E->getArg(1)->getType()->hasFloatingRepresentation() &&
+           E->getArg(2)->getType()->hasFloatingRepresentation() &&
+           "FaceForward operands must have a float representation");
+    return Builder.CreateIntrinsic(
+        /*ReturnType=*/N->getType(), Intrinsic::spv_faceforward,
+        ArrayRef<Value *>{N, I, Ng}, /*FMFSource=*/nullptr, "spv.faceforward");
+  }
   }
   return nullptr;
 }

clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h

@@ -126,6 +126,14 @@ template <typename T> constexpr vector<T, 4> lit_impl(T NDotL, T NDotH, T M) {
   return Result;
 }
 
+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
+}
+
 } // namespace __detail
 } // namespace hlsl
 

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -214,6 +214,53 @@ const inline double4 dst(double4 Src0, double4 Src1) {
   return __detail::dst_impl(Src0, Src1);
 }
 
+//===----------------------------------------------------------------------===//
+// faceforward builtin
+//===----------------------------------------------------------------------===//
+
+/// \fn T faceforward(T N, T I, T Ng)
+/// \brief Flips the surface-normal (if needed) to face in a direction opposite
+/// to \a I. Returns the result in terms of \a N.
+/// \param N The resulting floating-point surface-normal vector.
+/// \param I A floating-point, incident vector that points from the view
+/// position to the shading position.
+/// \param Ng A floating-point surface-normal vector.
+///
+/// Return a floating-point, surface normal vector that is facing the view
+/// direction.
+
+template <typename T>
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+const inline __detail::enable_if_t<__detail::is_arithmetic<T>::Value &&
+                                       __detail::is_same<half, T>::value,
+                                   T> faceforward(T N, T I, T Ng) {
+  return __detail::faceforward_impl(N, I, Ng);
+}
+
+template <typename T>
+const inline __detail::enable_if_t<
+    __detail::is_arithmetic<T>::Value && __detail::is_same<float, T>::value, T>
+faceforward(T N, T I, T Ng) {
+  return __detail::faceforward_impl(N, I, Ng);
+}
+
+template <int L>
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+const inline __detail::HLSL_FIXED_VECTOR<half, L> faceforward(
+    __detail::HLSL_FIXED_VECTOR<half, L> N,
+    __detail::HLSL_FIXED_VECTOR<half, L> I,
+    __detail::HLSL_FIXED_VECTOR<half, L> Ng) {
+  return __detail::faceforward_impl(N, I, Ng);
+}
+
+template <int L>
+const inline __detail::HLSL_FIXED_VECTOR<float, L>
+faceforward(__detail::HLSL_FIXED_VECTOR<float, L> N,
+            __detail::HLSL_FIXED_VECTOR<float, L> I,
+            __detail::HLSL_FIXED_VECTOR<float, L> Ng) {
+  return __detail::faceforward_impl(N, I, Ng);
+}
+
 //===----------------------------------------------------------------------===//
 // fmod builtins
 //===----------------------------------------------------------------------===//

clang/lib/Sema/SemaSPIRV.cpp

@@ -16,6 +16,23 @@ namespace clang {
 
 SemaSPIRV::SemaSPIRV(Sema &S) : SemaBase(S) {}
 
+static bool CheckAllArgsHaveSameType(Sema *S, CallExpr *TheCall) {
+  assert(TheCall->getNumArgs() > 1);
+  QualType ArgTy0 = TheCall->getArg(0)->getType();
+
+  for (unsigned I = 1, N = TheCall->getNumArgs(); I < N; ++I) {
+    if (!S->getASTContext().hasSameUnqualifiedType(
+            ArgTy0, TheCall->getArg(I)->getType())) {
+      S->Diag(TheCall->getBeginLoc(), diag::err_vec_builtin_incompatible_vector)
+          << TheCall->getDirectCallee() << /*useAllTerminology*/ true
+          << SourceRange(TheCall->getArg(0)->getBeginLoc(),
+                         TheCall->getArg(N - 1)->getEndLoc());
+      return true;
+    }
+  }
+  return false;
+}
+
 bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
                                               CallExpr *TheCall) {
   switch (BuiltinID) {
@@ -105,35 +122,41 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     if (SemaRef.checkArgCount(TheCall, 3))
       return true;
 
-    // check if the all arguments have floating representation
-    for (unsigned i = 0; i < TheCall->getNumArgs(); ++i) {
-      ExprResult Arg = TheCall->getArg(i);
-      QualType ArgTy = Arg.get()->getType();
-      if (!ArgTy->hasFloatingRepresentation()) {
-        SemaRef.Diag(Arg.get()->getBeginLoc(),
-                     diag::err_builtin_invalid_arg_type)
-            << i + 1 << /* scalar or vector */ 5 << /* no int */ 0 << /* fp */ 1
-            << ArgTy;
-        return true;
-      }
+    // Check if first argument has floating representation
+    ExprResult A = TheCall->getArg(0);
+    QualType ArgTyA = A.get()->getType();
+    if (!ArgTyA->hasFloatingRepresentation()) {
+      SemaRef.Diag(A.get()->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << /* ordinal */ 1 << /* scalar or vector */ 5 << /* no int */ 0
+          << /* fp */ 1 << ArgTyA;
+      return true;
     }
 
-    // check if all arguments are of the same type
+    if (CheckAllArgsHaveSameType(&SemaRef, TheCall))
+      return true;
+
+    QualType RetTy = ArgTyA;
+    TheCall->setType(RetTy);
+    break;
+  }
+  case SPIRV::BI__builtin_spirv_faceforward: {
+    if (SemaRef.checkArgCount(TheCall, 3))
+      return true;
+
+    // Check if first argument has floating representation
     ExprResult A = TheCall->getArg(0);
-    ExprResult B = TheCall->getArg(1);
-    ExprResult C = TheCall->getArg(2);
-    if (!(SemaRef.getASTContext().hasSameUnqualifiedType(A.get()->getType(),
-                                                         B.get()->getType()) &&
-          SemaRef.getASTContext().hasSameUnqualifiedType(A.get()->getType(),
-                                                         C.get()->getType()))) {
-      SemaRef.Diag(TheCall->getBeginLoc(),
-                   diag::err_vec_builtin_incompatible_vector)
-          << TheCall->getDirectCallee() << /*useAllTerminology*/ true
-          << SourceRange(A.get()->getBeginLoc(), C.get()->getEndLoc());
+    QualType ArgTyA = A.get()->getType();
+    if (!ArgTyA->hasFloatingRepresentation()) {
+      SemaRef.Diag(A.get()->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << /* ordinal */ 1 << /* scalar or vector */ 5 << /* no int */ 0
+          << /* fp */ 1 << ArgTyA;
       return true;
     }
 
-    QualType RetTy = A.get()->getType();
+    if (CheckAllArgsHaveSameType(&SemaRef, TheCall))
+      return true;
+
+    QualType RetTy = ArgTyA;
     TheCall->setType(RetTy);
     break;
   }

clang/test/CodeGenHLSL/builtins/faceforward.hlsl

@@ -0,0 +1,94 @@
+// RUN: %clang_cc1 -finclude-default-header -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -finclude-default-header -triple \
+// RUN:   spirv-unknown-vulkan-compute %s -fnative-half-type \
+// RUN:   -emit-llvm -o - | FileCheck %s --check-prefix=SPVCHECK
+
+// CHECK-LABEL: test_faceforward_half
+// CHECK: %hlsl.dot.i = fmul reassoc nnan ninf nsz arcp afn 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 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> %{{.*}})
+// 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: %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: %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
+// CHECK: %hlsl.dot.i = fmul reassoc nnan ninf nsz arcp afn 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 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: %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: %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: %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); }

clang/test/CodeGenSPIRV/Builtins/faceforward.c

@@ -0,0 +1,67 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
+
+// RUN: %clang_cc1 -O1 -triple spirv-pc-vulkan-compute %s -emit-llvm -o - | FileCheck %s
+
+typedef _Float16 half;
+typedef half half2 __attribute__((ext_vector_type(2)));
+typedef half half3 __attribute__((ext_vector_type(3)));
+typedef half half4 __attribute__((ext_vector_type(4)));
+typedef float float2 __attribute__((ext_vector_type(2)));
+typedef float float3 __attribute__((ext_vector_type(3)));
+typedef float float4 __attribute__((ext_vector_type(4)));
+
+// CHECK-LABEL: define spir_func half @test_faceforward_half(
+// CHECK-SAME: half noundef [[N:%.*]], half noundef [[I:%.*]], half noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call half @llvm.spv.faceforward.f16(half [[N]], half [[I]], half [[NG]])
+// CHECK-NEXT:    ret half [[SPV_FACEFORWARD]]
+half test_faceforward_half(half N, half I, half Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <2 x half> @test_faceforward_half2(
+// CHECK-SAME: <2 x half> noundef [[N:%.*]], <2 x half> noundef [[I:%.*]], <2 x half> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <2 x half> @llvm.spv.faceforward.v2f16(<2 x half> [[N]], <2 x half> [[I]], <2 x half> [[NG]])
+// CHECK-NEXT:    ret <2 x half> [[SPV_FACEFORWARD]]
+half2 test_faceforward_half2(half2 N, half2 I, half2 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <3 x half> @test_faceforward_half3(
+// CHECK-SAME: <3 x half> noundef [[N:%.*]], <3 x half> noundef [[I:%.*]], <3 x half> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <3 x half> @llvm.spv.faceforward.v3f16(<3 x half> [[N]], <3 x half> [[I]], <3 x half> [[NG]])
+// CHECK-NEXT:    ret <3 x half> [[SPV_FACEFORWARD]]
+half3 test_faceforward_half3(half3 N, half3 I, half3 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <4 x half> @test_faceforward_half4(
+// CHECK-SAME: <4 x half> noundef [[N:%.*]], <4 x half> noundef [[I:%.*]], <4 x half> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <4 x half> @llvm.spv.faceforward.v4f16(<4 x half> [[N]], <4 x half> [[I]], <4 x half> [[NG]])
+// CHECK-NEXT:    ret <4 x half> [[SPV_FACEFORWARD]]
+half4 test_faceforward_half4(half4 N, half4 I, half4 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func float @test_faceforward_float(
+// CHECK-SAME: float noundef [[N:%.*]], float noundef [[I:%.*]], float noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call float @llvm.spv.faceforward.f32(float [[N]], float [[I]], float [[NG]])
+// CHECK-NEXT:    ret float [[SPV_FACEFORWARD]]
+float test_faceforward_float(float N, float I, float Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <2 x float> @test_faceforward_float2(
+// CHECK-SAME: <2 x float> noundef [[N:%.*]], <2 x float> noundef [[I:%.*]], <2 x float> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <2 x float> @llvm.spv.faceforward.v2f32(<2 x float> [[N]], <2 x float> [[I]], <2 x float> [[NG]])
+// CHECK-NEXT:    ret <2 x float> [[SPV_FACEFORWARD]]
+float2 test_faceforward_float2(float2 N, float2 I, float2 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <3 x float> @test_faceforward_float3(
+// CHECK-SAME: <3 x float> noundef [[N:%.*]], <3 x float> noundef [[I:%.*]], <3 x float> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <3 x float> @llvm.spv.faceforward.v3f32(<3 x float> [[N]], <3 x float> [[I]], <3 x float> [[NG]])
+// CHECK-NEXT:    ret <3 x float> [[SPV_FACEFORWARD]]
+float3 test_faceforward_float3(float3 N, float3 I, float3 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }
+
+// CHECK-LABEL: define spir_func <4 x float> @test_faceforward_float4(
+// CHECK-SAME: <4 x float> noundef [[N:%.*]], <4 x float> noundef [[I:%.*]], <4 x float> noundef [[NG:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[SPV_FACEFORWARD:%.*]] = tail call <4 x float> @llvm.spv.faceforward.v4f32(<4 x float> [[N]], <4 x float> [[I]], <4 x float> [[NG]])
+// CHECK-NEXT:    ret <4 x float> [[SPV_FACEFORWARD]]
+float4 test_faceforward_float4(float4 N, float4 I, float4 Ng) { return __builtin_spirv_faceforward(N, I, Ng); }