RKSimon created this revision.
RKSimon added reviewers: rsmith, craig.topper, erichkeane.
Herald added a project: clang.
RKSimon requested review of this revision.
As suggested by @rsmith on PR47267, by replacing the __builtin_memcpy bitcast
pattern with __builtin_bit_cast we can use _castf32_u32, _castu32_f32,
_castf64_u64 and _castu64_f64 inside constant expresssions (constexpr).
Although __builtin_bit_cast was added for c++20 it works on all clang c/c++
modes.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D86398
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Headers/ia32intrin.h
clang/test/CodeGen/x86-builtins.c
Index: clang/test/CodeGen/x86-builtins.c
===================================================================
--- clang/test/CodeGen/x86-builtins.c
+++ clang/test/CodeGen/x86-builtins.c
@@ -1,45 +1,43 @@
-// RUN: %clang_cc1 -ffreestanding %s -triple=x86_64-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s -check-prefix=CHECK-64
-// RUN: %clang_cc1 -ffreestanding %s -triple=i386-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s -check-prefix=CHECK-32
+// RUN: %clang_cc1 -x c -ffreestanding %s -triple=x86_64-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s
+// RUN: %clang_cc1 -x c -ffreestanding %s -triple=i386-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s
+// RUN: %clang_cc1 -x c++ -std=c++11 -ffreestanding %s -triple=x86_64-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s
+// RUN: %clang_cc1 -x c++ -std=c++11 -ffreestanding %s -triple=i386-unknown-unknown -emit-llvm -o - -Wall -Werror | FileCheck %s
#include <x86intrin.h>
unsigned int test_castf32_u32 (float __A){
- // CHECK-64-LABEL: @test_castf32_u32
- // CHECK-64: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %{{.*}}, i8* align 4 %{{.*}}, i64 4, i1 false)
- // CHECK-64: %{{.*}} = load i32, i32* %{{.*}}, align 4
- // CHECK-32-LABEL: @test_castf32_u32
- // CHECK-32: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %{{.*}}, i8* align 4 %{{.*}}, i32 4, i1 false)
- // CHECK-32: %{{.*}} = load i32, i32* %{{.*}}, align 4
+ // CHECK-LABEL: test_castf32_u32
+ // CHECK: bitcast float* %{{.*}} to i32*
+ // CHECK: %{{.*}} = load i32, i32* %{{.*}}, align 4
return _castf32_u32(__A);
}
unsigned long long test_castf64_u64 (double __A){
- // CHECK-64-LABEL: @test_castf64_u64
- // CHECK-64: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %{{.*}}, i8* align 8 %{{.*}}, i64 8, i1 false)
- // CHECK-64: %{{.*}} = load i64, i64* %{{.*}}, align 8
- // CHECK-32-LABEL: @test_castf64_u64
- // CHECK-32: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %{{.*}}, i8* align 8 %{{.*}}, i32 8, i1 false)
- // CHECK-32: %{{.*}} = load i64, i64* %{{.*}}, align 8
+ // CHECK-LABEL: test_castf64_u64
+ // CHECK: bitcast double* %{{.*}} to i64*
+ // CHECK: %{{.*}} = load i64, i64* %{{.*}}, align 8
return _castf64_u64(__A);
}
float test_castu32_f32 (unsigned int __A){
- // CHECK-64-LABEL: @test_castu32_f32
- // CHECK-64: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %{{.*}}, i8* align 4 %{{.*}}, i64 4, i1 false)
- // CHECK-64: %{{.*}} = load float, float* %{{.*}}, align 4
- // CHECK-32-LABEL: @test_castu32_f32
- // CHECK-32: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %{{.*}}, i8* align 4 %{{.*}}, i32 4, i1 false)
- // CHECK-32: %{{.*}} = load float, float* %{{.*}}, align 4
+ // CHECK-LABEL: test_castu32_f32
+ // CHECK: bitcast i32* %{{.*}} to float*
+ // CHECK: %{{.*}} = load float, float* %{{.*}}, align 4
return _castu32_f32(__A);
}
double test_castu64_f64 (unsigned long long __A){
- // CHECK-64-LABEL: @test_castu64_f64
- // CHECK-64: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %{{.*}}, i8* align 8 %{{.*}}, i64 8, i1 false)
- // CHECK-64: %{{.*}} = load double, double* %{{.*}}, align 8
- // CHECK-32-LABEL: @test_castu64_f64
- // CHECK-32: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %{{.*}}, i8* align 8 %{{.*}}, i32 8, i1 false)
- // CHECK-32: %{{.*}} = load double, double* %{{.*}}, align 8
+ // CHECK-LABEL: test_castu64_f64
+ // CHECK: bitcast i64* %{{.*}} to double*
+ // CHECK: %{{.*}} = load double, double* %{{.*}}, align 8
return _castu64_f64(__A);
}
+// Test constexpr handling.
+#if defined(__cplusplus) && (__cplusplus >= 201103L)
+char cast_f32_u32_0[_castf32_u32(-0.0f) == 0x80000000 ? 1 : -1];
+char cast_u32_f32_0[_castu32_f32(0x3F800000) == +1.0f ? 1 : -1];
+
+char castf64_u64_0[_castf64_u64(-0.0) == 0x8000000000000000 ? 1 : -1];
+char castu64_f64_0[_castu64_f64(0xBFF0000000000000ULL) == -1.0 ? 1 : -1];
+#endif
Index: clang/lib/Headers/ia32intrin.h
===================================================================
--- clang/lib/Headers/ia32intrin.h
+++ clang/lib/Headers/ia32intrin.h
@@ -16,12 +16,13 @@
/* Define the default attributes for the functions in this file. */
#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__))
-#define __DEFAULT_FN_ATTRS_CAST __attribute__((__always_inline__))
#define __DEFAULT_FN_ATTRS_SSE42 __attribute__((__always_inline__, __nodebug__, __target__("sse4.2")))
#if defined(__cplusplus) && (__cplusplus >= 201103L)
+#define __DEFAULT_FN_ATTRS_CAST __attribute__((__always_inline__)) constexpr
#define __DEFAULT_FN_ATTRS_CONSTEXPR __DEFAULT_FN_ATTRS constexpr
#else
+#define __DEFAULT_FN_ATTRS_CAST __attribute__((__always_inline__))
#define __DEFAULT_FN_ATTRS_CONSTEXPR __DEFAULT_FN_ATTRS
#endif
@@ -218,9 +219,7 @@
*/
static __inline__ unsigned int __DEFAULT_FN_ATTRS_CAST
_castf32_u32(float __A) {
- unsigned int D;
- __builtin_memcpy(&D, &__A, sizeof(__A));
- return D;
+ return __builtin_bit_cast(unsigned int, __A);
}
/** Cast a 64-bit float value to a 64-bit unsigned integer value
@@ -235,9 +234,7 @@
*/
static __inline__ unsigned long long __DEFAULT_FN_ATTRS_CAST
_castf64_u64(double __A) {
- unsigned long long D;
- __builtin_memcpy(&D, &__A, sizeof(__A));
- return D;
+ return __builtin_bit_cast(unsigned long long, __A);
}
/** Cast a 32-bit unsigned integer value to a 32-bit float value
@@ -252,9 +249,7 @@
*/
static __inline__ float __DEFAULT_FN_ATTRS_CAST
_castu32_f32(unsigned int __A) {
- float D;
- __builtin_memcpy(&D, &__A, sizeof(__A));
- return D;
+ return __builtin_bit_cast(float, __A);
}
/** Cast a 64-bit unsigned integer value to a 64-bit float value
@@ -269,9 +264,7 @@
*/
static __inline__ double __DEFAULT_FN_ATTRS_CAST
_castu64_f64(unsigned long long __A) {
- double D;
- __builtin_memcpy(&D, &__A, sizeof(__A));
- return D;
+ return __builtin_bit_cast(double, __A);
}
/** Adds the unsigned integer operand to the CRC-32C checksum of the
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -179,6 +179,9 @@
- The x86 intrinsics ``__bswap``, ``__bswapd``, ``__bswap64`` and ``__bswapq``
may now be used within constant expressions.
+- The x86 intrinsics ``_castf32_u32``, ``_castf64_u64``, ``_castu32_f32`` and
+ ``_castu64_f64`` may now be used within constant expressions.
+
Internal API Changes
--------------------
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