[HLSL] Remove double pow intrinsics (#86407)

Currently, the HLSL community is re-implementing its HLSL compiler, the
DirectX Shader Compiler (DXC), in LLVM/main piece by piece. This change
removes the pow intrinsics with parameters of type double as it is not
available in DXC.

Introduced in
df5137e.

Documentation for HLSL pow function is available here:
https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-pow#parameters

Closes #86181

Author: robincaloudis

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -1174,15 +1174,6 @@ float3 pow(float3, float3);
 _HLSL_BUILTIN_ALIAS(__builtin_elementwise_pow)
 float4 pow(float4, float4);
 
-_HLSL_BUILTIN_ALIAS(__builtin_elementwise_pow)
-double pow(double, double);
-_HLSL_BUILTIN_ALIAS(__builtin_elementwise_pow)
-double2 pow(double2, double2);
-_HLSL_BUILTIN_ALIAS(__builtin_elementwise_pow)
-double3 pow(double3, double3);
-_HLSL_BUILTIN_ALIAS(__builtin_elementwise_pow)
-double4 pow(double4, double4);
-
 //===----------------------------------------------------------------------===//
 // reversebits builtins
 //===----------------------------------------------------------------------===//

clang/test/CodeGenHLSL/builtins/pow.hlsl

@@ -39,16 +39,3 @@ float3 test_pow_float3(float3 p0, float3 p1) { return pow(p0, p1); }
 // CHECK: define noundef <4 x float> @"?test_pow_float4
 // CHECK: call <4 x float> @llvm.pow.v4f32
 float4 test_pow_float4(float4 p0, float4 p1) { return pow(p0, p1); }
-
-// CHECK: define noundef double @"?test_pow_double@@YANNN@Z"(
-// CHECK: call double @llvm.pow.f64(
-double test_pow_double(double p0, double p1) { return pow(p0, p1); }
-// CHECK: define noundef <2 x double> @"?test_pow_double2@@YAT?$__vector@N$01@__clang@@T12@0@Z"(
-// CHECK: call <2 x double> @llvm.pow.v2f64
-double2 test_pow_double2(double2 p0, double2 p1) { return pow(p0, p1); }
-// CHECK: define noundef <3 x double> @"?test_pow_double3@@YAT?$__vector@N$02@__clang@@T12@0@Z"(
-// CHECK: call <3 x double> @llvm.pow.v3f64
-double3 test_pow_double3(double3 p0, double3 p1) { return pow(p0, p1); }
-// CHECK: define noundef <4 x double> @"?test_pow_double4@@YAT?$__vector@N$03@__clang@@T12@0@Z"(
-// CHECK: call <4 x double> @llvm.pow.v4f64
-double4 test_pow_double4(double4 p0, double4 p1) { return pow(p0, p1); }