From f8e0e5db48601cb0d019405703ccaa2378f503e0 Mon Sep 17 00:00:00 2001 From: Simon Pilgrim Date: Sun, 23 Aug 2020 10:27:46 +0100 Subject: [PATCH] [X86] Enable constexpr on _cast fp<-> uint intrinsics (PR31446) 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. Differential Revision: https://reviews.llvm.org/D86398 --- clang/docs/ReleaseNotes.rst | 3 +++ clang/lib/Headers/ia32intrin.h | 19 +++++---------- clang/test/CodeGen/x86-builtins.c | 50 +++++++++++++++++++-------------------- 3 files changed, 33 insertions(+), 39 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index ba2b540..b4e594a 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -179,6 +179,9 @@ X86 Support in Clang - 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 -------------------- diff --git a/clang/lib/Headers/ia32intrin.h b/clang/lib/Headers/ia32intrin.h index 1d17a56..f01a3ad 100644 --- a/clang/lib/Headers/ia32intrin.h +++ b/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 @@ __writeeflags(unsigned int __f) */ 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 @@ _castf32_u32(float __A) { */ 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 @@ _castf64_u64(double __A) { */ 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 @@ _castu32_f32(unsigned int __A) { */ 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 diff --git a/clang/test/CodeGen/x86-builtins.c b/clang/test/CodeGen/x86-builtins.c index fa2530b..6604e1f 100644 --- a/clang/test/CodeGen/x86-builtins.c +++ b/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 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 -- 2.7.4