create int_spv_faceforward intrinsic, create faceforward lowering & map to int_spv_faceforward, create SPIR-V backend test case

Author: kmpeng

llvm/include/llvm/IR/IntrinsicsSPIRV.td

@@ -67,6 +67,7 @@ let TargetPrefix = "spv" in {
   def int_spv_cross : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>, LLVMMatchType<0>], [IntrNoMem]>;
   def int_spv_degrees : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty], [IntrNoMem]>;
   def int_spv_distance : DefaultAttrsIntrinsic<[LLVMVectorElementType<0>], [llvm_anyfloat_ty, LLVMMatchType<0>], [IntrNoMem]>;
+  def int_spv_faceforward : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty, LLVMMatchType<0>, LLVMMatchType<0>], [IntrNoMem]>;
   def int_spv_frac : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty], [IntrNoMem]>;
   def int_spv_lerp : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty, LLVMMatchType<0>,LLVMMatchType<0>],
     [IntrNoMem] >;

llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

@@ -3083,6 +3083,8 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
     return selectExtInst(ResVReg, ResType, I, CL::length, GL::Length);
   case Intrinsic::spv_degrees:
     return selectExtInst(ResVReg, ResType, I, CL::degrees, GL::Degrees);
+  case Intrinsic::spv_faceforward:
+    return selectExtInst(ResVReg, ResType, I, GL::FaceForward);
   case Intrinsic::spv_frac:
     return selectExtInst(ResVReg, ResType, I, CL::fract, GL::Fract);
   case Intrinsic::spv_normalize:

llvm/test/CodeGen/SPIRV/hlsl-intrinsics/faceforward.ll

@@ -0,0 +1,35 @@
+; RUN: llc -O0 -verify-machineinstrs -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val --target-env vulkan1.3 %}
+
+; Make sure SPIRV operation function calls for faceforward are lowered correctly.
+
+; CHECK-DAG: %[[#op_ext_glsl:]] = OpExtInstImport "GLSL.std.450"
+; CHECK-DAG: %[[#float_16:]] = OpTypeFloat 16
+; CHECK-DAG: %[[#vec4_float_16:]] = OpTypeVector %[[#float_16]] 4
+; CHECK-DAG: %[[#float_32:]] = OpTypeFloat 32
+; CHECK-DAG: %[[#vec4_float_32:]] = OpTypeVector %[[#float_32]] 4
+
+define noundef <4 x half> @faceforward_half4(<4 x half> noundef %a, <4 x half> noundef %b, <4 x half> noundef %c) {
+entry:
+  ; CHECK: %[[#]] = OpFunction %[[#vec4_float_16]] None %[[#]]
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#vec4_float_16]]
+  ; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#vec4_float_16]]
+  ; CHECK: %[[#arg2:]] = OpFunctionParameter %[[#vec4_float_16]]
+  ; CHECK: %[[#]] = OpExtInst %[[#vec4_float_16]] %[[#op_ext_glsl]] FaceForward %[[#arg0]] %[[#arg1]] %[[#arg2]]
+  %spv.faceforward = call <4 x half> @llvm.spv.faceforward.f16(<4 x half> %a, <4 x half> %b, <4 x half> %c)
+  ret <4 x half> %spv.faceforward
+}
+
+define noundef <4 x float> @faceforward_float4(<4 x float> noundef %a, <4 x float> noundef %b, <4 x float> noundef %c) {
+entry:
+  ; CHECK: %[[#]] = OpFunction %[[#vec4_float_32]] None %[[#]]
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#vec4_float_32]]
+  ; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#vec4_float_32]]
+  ; CHECK: %[[#arg2:]] = OpFunctionParameter %[[#vec4_float_32]]
+  ; CHECK: %[[#]] = OpExtInst %[[#vec4_float_32]] %[[#op_ext_glsl]] FaceForward %[[#arg0]] %[[#arg1]] %[[#arg2]]
+  %spv.faceforward = call <4 x float> @llvm.spv.faceforward.f32(<4 x float> %a, <4 x float> %b, <4 x float> %c)
+  ret <4 x float> %spv.faceforward
+}
+
+declare <4 x half> @llvm.spv.faceforward.f16(<4 x half>, <4 x half>, <4 x half>)
+declare <4 x float> @llvm.spv.faceforward.f32(<4 x float>, <4 x float>, <4 x float>)