add floor library function

[bob80905]

Summary

This change exposes the floor library function for HLSL,
excluding long, int, and long long doubles.
Floor 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 floor function only works on floating type arguments.

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

[bob80905]

• update with clang format

[beanz]

LGTM. @bob80905 if you haven't already, you should follow the steps here (https://www.llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access) to get commit access.

clang/lib/Headers/hlsl/hlsl_intrinsics.h

 ceil(double);
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double2 ceil(double2);
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double3 ceil(double3);
 __attribute__((clang_builtin_alias(__builtin_elementwise_ceil)))
 double4 ceil(double4);
 
+// floor builtins
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half floor(half);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half2 floor(half2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half3 floor(half3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+half4 floor(half4);
+#endif
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor))) float
+floor(float);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float2 floor(float2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float3 floor(float3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+float4 floor(float4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor))) double
+floor(double);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double2 floor(double2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double3 floor(double3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_floor)))
+double4 floor(double4);
+
 // 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)))

clang/test/CodeGenHLSL/builtins/floor.hlsl

+// 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
+
+using hlsl::floor;
+
+// CHECK: define noundef half @
+// CHECK: call half @llvm.floor.f16(
+// NO_HALF: define noundef float @"?test_floor_half@@YA$halff@$halff@@Z"(
+// NO_HALF: call float @llvm.floor.f32(float %0)
+half test_floor_half ( half p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x half> @
+// CHECK: call <2 x half> @llvm.floor.v2f16(
+// NO_HALF: define noundef <2 x float> @"?test_floor_half2@@YAT?$__vector@$halff@$01@__clang@@T12@@Z"(
+// NO_HALF: call <2 x float> @llvm.floor.v2f32(
+half2 test_floor_half2 ( half2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x half> @
+// CHECK: call <3 x half> @llvm.floor.v3f16(
+// NO_HALF: define noundef <3 x float> @"?test_floor_half3@@YAT?$__vector@$halff@$02@__clang@@T12@@Z"(
+// NO_HALF: call <3 x float> @llvm.floor.v3f32(
+half3 test_floor_half3 ( half3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x half> @
+// CHECK: call <4 x half> @llvm.floor.v4f16(
+// NO_HALF: define noundef <4 x float> @"?test_floor_half4@@YAT?$__vector@$halff@$03@__clang@@T12@@Z"(
+// NO_HALF: call <4 x float> @llvm.floor.v4f32(
+half4 test_floor_half4 ( half4 p0 ) {
+  return floor ( p0 );
+}
+
+// CHECK: define noundef float @
+// CHECK: call float @llvm.floor.f32(
+float test_floor_float ( float p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x float> @
+// CHECK: call <2 x float> @llvm.floor.v2f32(
+float2 test_floor_float2 ( float2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x float> @
+// CHECK: call <3 x float> @llvm.floor.v3f32(
+float3 test_floor_float3 ( float3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x float> @
+// CHECK: call <4 x float> @llvm.floor.v4f32(
+float4 test_floor_float4 ( float4 p0 ) {
+  return floor ( p0 );
+}
+
+// CHECK: define noundef double @
+// CHECK: call double @llvm.floor.f64(
+double test_floor_double ( double p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <2 x double> @
+// CHECK: call <2 x double> @llvm.floor.v2f64(
+double2 test_floor_double2 ( double2 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <3 x double> @
+// CHECK: call <3 x double> @llvm.floor.v3f64(
+double3 test_floor_double3 ( double3 p0 ) {
+  return floor ( p0 );
+}
+// CHECK: define noundef <4 x double> @
+// CHECK: call <4 x double> @llvm.floor.v4f64(
+double4 test_floor_double4 ( double4 p0 ) {
+  return floor ( p0 );
+}