[HLSL] add cos library function

This change exposes the cos library function for HLSL,
excluding long, int, and long long doubles.
Cos is supported for all scalar, vector, and matrix types.

Long and long long double support is missing in this patch because those types
don't exist in HLSL. Int is missing because the cos function only works on floating type arguments.

The full documentation of the HLSL cos function is available here:
https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-cos

Reviewed By: python3kgae

Differential Revision: https://reviews.llvm.org/D134921

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -101,6 +101,34 @@ double3 ceil(double3);
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double4 ceil(double4);
 
-} // namespace hlsl
+// cos builtins
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos))) half cos(half);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half2 cos(half2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half3 cos(half3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+half4 cos(half4);
+#endif
 
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos))) float
+cos(float);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float2 cos(float2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float3 cos(float3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+float4 cos(float4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos))) double
+cos(double);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+double2 cos(double2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+double3 cos(double3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_cos)))
+double4 cos(double4);
+
+} // namespace hlsl
 #endif //_HLSL_HLSL_INTRINSICS_H_

clang/test/CodeGenHLSL/builtins/cos.hlsl

@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -emit-llvm -disable-llvm-passes -O3 -o - | FileCheck %s
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm -disable-llvm-passes \
+// RUN:   -D__HLSL_ENABLE_16_BIT -o - | FileCheck %s --check-prefix=NO_HALF
+
+// CHECK: define noundef half @
+// CHECK: call half @llvm.cos.f16(
+// NO_HALF: define noundef float @"?test_cos_half@@YA$halff@$halff@@Z"(
+// NO_HALF: call float @llvm.cos.f32(
+half test_cos_half ( half p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <2 x half> @
+// CHECK: call <2 x half> @llvm.cos.v2f16
+// NO_HALF: define noundef <2 x float> @"?test_cos_float2@@YAT?$__vector@M$01@__clang@@T12@@Z"(
+// NO_HALF: call <2 x float> @llvm.cos.v2f32(
+half2 test_cos_half2 ( half2 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <3 x half> @
+// CHECK: call <3 x half> @llvm.cos.v3f16
+// NO_HALF: define noundef <3 x float> @"?test_cos_float3@@YAT?$__vector@M$02@__clang@@T12@@Z"(
+// NO_HALF: call <3 x float> @llvm.cos.v3f32(
+half3 test_cos_half3 ( half3 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <4 x half> @
+// CHECK: call <4 x half> @llvm.cos.v4f16
+// NO_HALF: define noundef <4 x float> @"?test_cos_float4@@YAT?$__vector@M$03@__clang@@T12@@Z"(
+// NO_HALF: call <4 x float> @llvm.cos.v4f32(
+half4 test_cos_half4 ( half4 p0 ) {
+  return cos ( p0 );
+}
+
+// CHECK: define noundef float @
+// CHECK: call float @llvm.cos.f32(
+float test_cos_float ( float p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <2 x float> @
+// CHECK: call <2 x float> @llvm.cos.v2f32
+float2 test_cos_float2 ( float2 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <3 x float> @
+// CHECK: call <3 x float> @llvm.cos.v3f32
+float3 test_cos_float3 ( float3 p0 ) {
+  return cos ( p0 );
+}
+// CHECK: define noundef <4 x float> @
+// CHECK: call <4 x float> @llvm.cos.v4f32
+float4 test_cos_float4 ( float4 p0 ) {
+  return cos ( p0 );
+}