Adding asuint implementation to hlsl (#107292)

Implements support for the `asuint` HLSL function casting behaviour.
Addressing the `splitdouble` scenario will be addressed in a future PR. 

Fixes: #70097

---------

Co-authored-by: Joao Saffran <[email protected]>
Co-authored-by: Justin Bogner <[email protected]>

Author: 3 people

clang/lib/Headers/CMakeLists.txt

@@ -87,6 +87,7 @@ set(hlsl_h
 set(hlsl_subdir_files
   hlsl/hlsl_basic_types.h
   hlsl/hlsl_intrinsics.h
+  hlsl/hlsl_detail.h
   )
 set(hlsl_files
   ${hlsl_h}

clang/lib/Headers/hlsl/hlsl_detail.h

@@ -0,0 +1,38 @@
+//===----- detail.h - HLSL definitions for intrinsics ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _HLSL_HLSL_DETAILS_H_
+#define _HLSL_HLSL_DETAILS_H_
+
+namespace hlsl {
+
+namespace __detail {
+
+#define _HLSL_INLINE                                                           \
+  __attribute__((__always_inline__, __nodebug__)) static inline
+
+template <bool B, typename T> struct enable_if {};
+
+template <typename T> struct enable_if<true, T> {
+  using Type = T;
+};
+
+template <typename U, typename T, int N>
+_HLSL_INLINE typename enable_if<sizeof(U) == sizeof(T), vector<U, N> >::Type
+bit_cast(vector<T, N> V) {
+  return __builtin_bit_cast(vector<U, N>, V);
+}
+
+template <typename U, typename T>
+_HLSL_INLINE typename enable_if<sizeof(U) == sizeof(T), U>::Type bit_cast(T F) {
+  return __builtin_bit_cast(U, F);
+}
+
+} // namespace __detail
+} // namespace hlsl
+#endif //_HLSL_HLSL_DETAILS_H_

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -9,6 +9,8 @@
 #ifndef _HLSL_HLSL_INTRINSICS_H_
 #define _HLSL_HLSL_INTRINSICS_H_
 
+#include "hlsl_detail.h"
+
 namespace hlsl {
 
 // Note: Functions in this file are sorted alphabetically, then grouped by base
@@ -387,6 +389,23 @@ float3 asin(float3);
 _HLSL_BUILTIN_ALIAS(__builtin_elementwise_asin)
 float4 asin(float4);
 
+//===----------------------------------------------------------------------===//
+// asuint builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn uint asuint(T Val)
+/// \brief Interprets the bit pattern of x as an unsigned integer.
+/// \param Val The input value.
+
+template <typename T, int N>
+_HLSL_INLINE vector<uint, N> asuint(vector<T, N> V) {
+  return __detail::bit_cast<uint, T, N>(V);
+}
+
+template <typename T> _HLSL_INLINE uint asuint(T F) {
+  return __detail::bit_cast<uint, T>(F);
+}
+
 //===----------------------------------------------------------------------===//
 // atan builtins
 //===----------------------------------------------------------------------===//

clang/test/CodeGenHLSL/builtins/asuint.hlsl

@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple dxil-pc-shadermodel6.3-library %s -fnative-half-type -emit-llvm -O1 -o - | FileCheck %s
+
+// CHECK: define {{.*}}test_uint{{.*}}(i32 {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK-NOT: bitcast
+// CHECK: ret i32 [[VAL]]
+uint test_uint(uint p0) {
+  return asuint(p0);
+}
+
+// CHECK: define {{.*}}test_int{{.*}}(i32 {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK-NOT: bitcast
+// CHECK: ret i32 [[VAL]]
+uint test_int(int p0) {
+  return asuint(p0);
+}
+
+// CHECK: define {{.*}}test_float{{.*}}(float {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK: bitcast float [[VAL]] to i32
+uint test_float(float p0) {
+  return asuint(p0);
+}
+
+// CHECK: define {{.*}}test_vector_uint{{.*}}(<4 x i32> {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK-NOT: bitcast
+// CHECK: ret <4 x i32> [[VAL]]
+uint4 test_vector_uint(uint4 p0) {
+  return asuint(p0);
+}
+
+// CHECK: define {{.*}}test_vector_int{{.*}}(<4 x i32> {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK-NOT: bitcast
+// CHECK: ret <4 x i32> [[VAL]]
+uint4 test_vector_int(int4 p0) {
+  return asuint(p0);
+}
+
+// CHECK: define {{.*}}test_vector_float{{.*}}(<4 x float> {{.*}} [[VAL:%.*]]){{.*}} 
+// CHECK: bitcast <4 x float> [[VAL]] to <4 x i32>
+uint4 test_vector_float(float4 p0) {
+  return asuint(p0);
+}

clang/test/SemaHLSL/BuiltIns/asuint-errors.hlsl

@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -verify
+
+
+uint4 test_asuint_too_many_arg(float p0, float p1) {
+  return asuint(p0, p1);
+  // expected-error@-1 {{no matching function for call to 'asuint'}}
+  // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires single argument 'V', but 2 arguments were provided}}
+  // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires single argument 'F', but 2 arguments were provided}}
+}
+
+uint test_asuint_double(double p1) {
+    return asuint(p1);
+    // expected-error@hlsl/hlsl_intrinsics.h:* {{no matching function for call to 'bit_cast'}}
+    // expected-note@-2 {{in instantiation of function template specialization 'hlsl::asuint<double>'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: could not match 'vector<double, N>' against 'double'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: substitution failure [with U = uint, T = double]: no type named 'Type'}}
+}
+
+uint test_asuint_half(half p1) {
+    return asuint(p1);
+    // expected-error@hlsl/hlsl_intrinsics.h:* {{no matching function for call to 'bit_cast'}}
+    // expected-note@-2 {{in instantiation of function template specialization 'hlsl::asuint<half>'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: could not match 'vector<half, N>' against 'half'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: substitution failure [with U = uint, T = half]: no type named 'Type'}}
+}