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Nov 28, 2025
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[Headers][X86] Convert bf16 to f32 conversions to constexpr implementations #169841

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c963664
[Headers][X86] Convert bf16 to f32 conversions to constexpr implement…
RKSimon Nov 27, 2025
237a4a9
Merge branch 'main' into x86-bf16-constexpr
RKSimon Nov 28, 2025
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19 changes: 15 additions & 4 deletions clang/lib/Headers/avx512bf16intrin.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,14 @@ typedef __bf16 __bfloat16 __attribute__((deprecated("use __bf16 instead")));
#define __DEFAULT_FN_ATTRS \
__attribute__((__always_inline__, __nodebug__, __target__("avx512bf16")))

#if defined(__cplusplus) && (__cplusplus >= 201103L)
#define __DEFAULT_FN_ATTRS512_CONSTEXPR __DEFAULT_FN_ATTRS512 constexpr
#define __DEFAULT_FN_ATTRS_CONSTEXPR __DEFAULT_FN_ATTRS constexpr
#else
#define __DEFAULT_FN_ATTRS512_CONSTEXPR __DEFAULT_FN_ATTRS512
#define __DEFAULT_FN_ATTRS_CONSTEXPR __DEFAULT_FN_ATTRS
#endif

/// Convert One BF16 Data to One Single Float Data.
///
/// \headerfile <x86intrin.h>
Expand All @@ -35,7 +43,7 @@ typedef __bf16 __bfloat16 __attribute__((deprecated("use __bf16 instead")));
/// A bfloat data.
/// \returns A float data whose sign field and exponent field keep unchanged,
/// and fraction field is extended to 23 bits.
static __inline__ float __DEFAULT_FN_ATTRS _mm_cvtsbh_ss(__bf16 __A) {
static __inline__ float __DEFAULT_FN_ATTRS_CONSTEXPR _mm_cvtsbh_ss(__bf16 __A) {
return (float)(__A);
}

Expand Down Expand Up @@ -235,7 +243,8 @@ _mm512_maskz_dpbf16_ps(__mmask16 __U, __m512 __D, __m512bh __A, __m512bh __B) {
/// \param __A
/// A 256-bit vector of [16 x bfloat].
/// \returns A 512-bit vector of [16 x float] come from conversion of __A
static __inline__ __m512 __DEFAULT_FN_ATTRS512 _mm512_cvtpbh_ps(__m256bh __A) {
static __inline__ __m512 __DEFAULT_FN_ATTRS512_CONSTEXPR
_mm512_cvtpbh_ps(__m256bh __A) {
return (__m512) __builtin_convertvector(__A, __v16sf);
}

Expand All @@ -249,7 +258,7 @@ static __inline__ __m512 __DEFAULT_FN_ATTRS512 _mm512_cvtpbh_ps(__m256bh __A) {
/// \param __A
/// A 256-bit vector of [16 x bfloat].
/// \returns A 512-bit vector of [16 x float] come from conversion of __A
static __inline__ __m512 __DEFAULT_FN_ATTRS512
static __inline__ __m512 __DEFAULT_FN_ATTRS512_CONSTEXPR
_mm512_maskz_cvtpbh_ps(__mmask16 __U, __m256bh __A) {
return (__m512)__builtin_ia32_selectps_512((__mmask16)__U,
(__v16sf)_mm512_cvtpbh_ps(__A),
Expand All @@ -268,14 +277,16 @@ _mm512_maskz_cvtpbh_ps(__mmask16 __U, __m256bh __A) {
/// \param __A
/// A 256-bit vector of [16 x bfloat].
/// \returns A 512-bit vector of [16 x float] come from conversion of __A
static __inline__ __m512 __DEFAULT_FN_ATTRS512
static __inline__ __m512 __DEFAULT_FN_ATTRS512_CONSTEXPR
_mm512_mask_cvtpbh_ps(__m512 __S, __mmask16 __U, __m256bh __A) {
return (__m512)__builtin_ia32_selectps_512(
(__mmask16)__U, (__v16sf)_mm512_cvtpbh_ps(__A), (__v16sf)__S);
}

#undef __DEFAULT_FN_ATTRS
#undef __DEFAULT_FN_ATTRS_CONSTEXPR
#undef __DEFAULT_FN_ATTRS512
#undef __DEFAULT_FN_ATTRS512_CONSTEXPR

#endif
#endif
24 changes: 18 additions & 6 deletions clang/lib/Headers/avx512vlbf16intrin.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,14 @@
__target__("avx512vl,avx512bf16"), \
__min_vector_width__(256)))

#if defined(__cplusplus) && (__cplusplus >= 201103L)
#define __DEFAULT_FN_ATTRS128_CONSTEXPR __DEFAULT_FN_ATTRS128 constexpr
#define __DEFAULT_FN_ATTRS256_CONSTEXPR __DEFAULT_FN_ATTRS256 constexpr
#else
#define __DEFAULT_FN_ATTRS128_CONSTEXPR __DEFAULT_FN_ATTRS128
#define __DEFAULT_FN_ATTRS256_CONSTEXPR __DEFAULT_FN_ATTRS256
#endif

/// Convert Two Packed Single Data to One Packed BF16 Data.
///
/// \headerfile <x86intrin.h>
Expand Down Expand Up @@ -421,7 +429,8 @@ static __inline__ __bf16 __DEFAULT_FN_ATTRS128 _mm_cvtness_sbh(float __A) {
/// \param __A
/// A 128-bit vector of [4 x bfloat].
/// \returns A 128-bit vector of [4 x float] come from conversion of __A
static __inline__ __m128 __DEFAULT_FN_ATTRS128 _mm_cvtpbh_ps(__m128bh __A) {
static __inline__ __m128 __DEFAULT_FN_ATTRS128_CONSTEXPR
_mm_cvtpbh_ps(__m128bh __A) {
return (__m128)_mm256_castps256_ps128(
(__m256) __builtin_convertvector(__A, __v8sf));
}
Expand All @@ -433,7 +442,8 @@ static __inline__ __m128 __DEFAULT_FN_ATTRS128 _mm_cvtpbh_ps(__m128bh __A) {
/// \param __A
/// A 128-bit vector of [8 x bfloat].
/// \returns A 256-bit vector of [8 x float] come from conversion of __A
static __inline__ __m256 __DEFAULT_FN_ATTRS256 _mm256_cvtpbh_ps(__m128bh __A) {
static __inline__ __m256 __DEFAULT_FN_ATTRS256_CONSTEXPR
_mm256_cvtpbh_ps(__m128bh __A) {
return (__m256) __builtin_convertvector(__A, __v8sf);
}

Expand All @@ -447,7 +457,7 @@ static __inline__ __m256 __DEFAULT_FN_ATTRS256 _mm256_cvtpbh_ps(__m128bh __A) {
/// \param __A
/// A 128-bit vector of [4 x bfloat].
/// \returns A 128-bit vector of [4 x float] come from conversion of __A
static __inline__ __m128 __DEFAULT_FN_ATTRS128
static __inline__ __m128 __DEFAULT_FN_ATTRS128_CONSTEXPR
_mm_maskz_cvtpbh_ps(__mmask8 __U, __m128bh __A) {
return (__m128)__builtin_ia32_selectps_128(
(__mmask8)__U, (__v4sf)_mm_cvtpbh_ps(__A), (__v4sf)_mm_setzero_ps());
Expand All @@ -463,7 +473,7 @@ _mm_maskz_cvtpbh_ps(__mmask8 __U, __m128bh __A) {
/// \param __A
/// A 128-bit vector of [8 x bfloat].
/// \returns A 256-bit vector of [8 x float] come from conversion of __A
static __inline__ __m256 __DEFAULT_FN_ATTRS256
static __inline__ __m256 __DEFAULT_FN_ATTRS256_CONSTEXPR
_mm256_maskz_cvtpbh_ps(__mmask8 __U, __m128bh __A) {
return (__m256)__builtin_ia32_selectps_256((__mmask8)__U,
(__v8sf)_mm256_cvtpbh_ps(__A),
Expand All @@ -483,7 +493,7 @@ _mm256_maskz_cvtpbh_ps(__mmask8 __U, __m128bh __A) {
/// \param __A
/// A 128-bit vector of [4 x bfloat].
/// \returns A 128-bit vector of [4 x float] come from conversion of __A
static __inline__ __m128 __DEFAULT_FN_ATTRS128
static __inline__ __m128 __DEFAULT_FN_ATTRS128_CONSTEXPR
_mm_mask_cvtpbh_ps(__m128 __S, __mmask8 __U, __m128bh __A) {
return (__m128)__builtin_ia32_selectps_128(
(__mmask8)__U, (__v4sf)_mm_cvtpbh_ps(__A), (__v4sf)__S);
Expand All @@ -502,14 +512,16 @@ _mm_mask_cvtpbh_ps(__m128 __S, __mmask8 __U, __m128bh __A) {
/// \param __A
/// A 128-bit vector of [8 x bfloat].
/// \returns A 256-bit vector of [8 x float] come from conversion of __A
static __inline__ __m256 __DEFAULT_FN_ATTRS256
static __inline__ __m256 __DEFAULT_FN_ATTRS256_CONSTEXPR
_mm256_mask_cvtpbh_ps(__m256 __S, __mmask8 __U, __m128bh __A) {
return (__m256)__builtin_ia32_selectps_256(
(__mmask8)__U, (__v8sf)_mm256_cvtpbh_ps(__A), (__v8sf)__S);
}

#undef __DEFAULT_FN_ATTRS128
#undef __DEFAULT_FN_ATTRS256
#undef __DEFAULT_FN_ATTRS128_CONSTEXPR
#undef __DEFAULT_FN_ATTRS256_CONSTEXPR

#endif
#endif
5 changes: 5 additions & 0 deletions clang/test/CodeGen/X86/avx512bf16-builtins.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,13 +9,15 @@
// RUN: %clang_cc1 -x c++ -flax-vector-conversions=none -ffreestanding %s -triple=i386-apple-darwin -target-feature +avx512bf16 -emit-llvm -o - -Wall -Werror -fexperimental-new-constant-interpreter | FileCheck %s

#include <immintrin.h>
#include "builtin_test_helpers.h"

float test_mm_cvtsbh_ss(__bf16 A) {
// CHECK-LABEL: test_mm_cvtsbh_ss
// CHECK: fpext bfloat %{{.*}} to float
// CHECK: ret float %{{.*}}
return _mm_cvtsbh_ss(A);
}
TEST_CONSTEXPR(_mm_cvtsbh_ss(-1.0f) == -1.0f);

__m512bh test_mm512_cvtne2ps_pbh(__m512 A, __m512 B) {
// CHECK-LABEL: test_mm512_cvtne2ps_pbh
Expand Down Expand Up @@ -82,17 +84,20 @@ __m512 test_mm512_cvtpbh_ps(__m256bh A) {
// CHECK: fpext <16 x bfloat> %{{.*}} to <16 x float>
return _mm512_cvtpbh_ps(A);
}
TEST_CONSTEXPR(match_m512(_mm512_cvtpbh_ps((__m256bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f, -128.0f, -0.5f, 0.25f, -0.125f, -4.0f, 2.0f, -1.0f, 0.0f}), -0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f, -128.0f, -0.5f, 0.25f, -0.125f, -4.0f, 2.0f, -1.0f, 0.0f));

__m512 test_mm512_maskz_cvtpbh_ps(__mmask16 M, __m256bh A) {
// CHECK-LABEL: test_mm512_maskz_cvtpbh_ps
// CHECK: fpext <16 x bfloat> %{{.*}} to <16 x float>
// CHECK: select <16 x i1> %{{.*}}, <16 x float> %{{.*}}, <16 x float> %{{.*}}
return _mm512_maskz_cvtpbh_ps(M, A);
}
TEST_CONSTEXPR(match_m512(_mm512_maskz_cvtpbh_ps(0xA753, (__m256bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f, -128.0f, -0.5f, 0.25f, -0.125f, -4.0f, 2.0f, -1.0f, 0.0f}), -0.0f, 1.0f, 0.0f, 0.0f, -8.0f, 0.0f, -32.0f, 0.0f, -128.0f, -0.5f, 0.25f, 0.0f, 0.0f, 2.0f, 0.0f, 0.0f));

__m512 test_mm512_mask_cvtpbh_ps(__m512 S, __mmask16 M, __m256bh A) {
// CHECK-LABEL: test_mm512_mask_cvtpbh_ps
// CHECK: fpext <16 x bfloat> %{{.*}} to <16 x float>
// CHECK: select <16 x i1> %{{.*}}, <16 x float> %{{.*}}, <16 x float> %{{.*}}
return _mm512_mask_cvtpbh_ps(S, M, A);
}
TEST_CONSTEXPR(match_m512(_mm512_mask_cvtpbh_ps((__m512){ 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f }, 0xA753, (__m256bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f, -128.0f, -0.5f, 0.25f, -0.125f, -4.0f, 2.0f, -1.0f, 0.0f}), -0.0f, 1.0f, 99.0f, 99.0f, -8.0f, 99.0f, -32.0f, 99.0f, -128.0f, -0.5f, 0.25f, 99.0f, 99.0f, 2.0f, 99.0f, 0.0f));
7 changes: 7 additions & 0 deletions clang/test/CodeGen/X86/avx512vlbf16-builtins.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
// RUN: %clang_cc1 -x c++ -flax-vector-conversions=none -ffreestanding %s -triple=i386-apple-darwin -target-feature +avx512bf16 -target-feature +avx512vl -emit-llvm -o - -Wall -Werror -fexperimental-new-constant-interpreter | FileCheck %s

#include <immintrin.h>
#include "builtin_test_helpers.h"

__m128bh test_mm_cvtne2ps2bf16(__m128 A, __m128 B) {
// CHECK-LABEL: test_mm_cvtne2ps2bf16
Expand Down Expand Up @@ -160,12 +161,14 @@ __m128 test_mm_cvtpbh_ps(__m128bh A) {
// CHECK: shufflevector <8 x float> %{{.*}}, <8 x float> %{{.*}}, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
return _mm_cvtpbh_ps(A);
}
TEST_CONSTEXPR(match_m128(_mm_cvtpbh_ps((__m128bh){-8.0f, 16.0f, -32.0f, 64.0f, -0.0f, 1.0f, -2.0f, 4.0f}), -8.0f, 16.0f, -32.0f, 64.0f));

__m256 test_mm256_cvtpbh_ps(__m128bh A) {
// CHECK-LABEL: test_mm256_cvtpbh_ps
// CHECK: fpext <8 x bfloat> %{{.*}} to <8 x float>
return _mm256_cvtpbh_ps(A);
}
TEST_CONSTEXPR(match_m256(_mm256_cvtpbh_ps((__m128bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f}), -0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f));

__m128 test_mm_maskz_cvtpbh_ps(__mmask8 M, __m128bh A) {
// CHECK-LABEL: test_mm_maskz_cvtpbh_ps
Expand All @@ -174,13 +177,15 @@ __m128 test_mm_maskz_cvtpbh_ps(__mmask8 M, __m128bh A) {
// CHECK: select <4 x i1> %{{.*}}, <4 x float> %{{.*}}, <4 x float> %{{.*}}
return _mm_maskz_cvtpbh_ps(M, A);
}
TEST_CONSTEXPR(match_m128(_mm_maskz_cvtpbh_ps(0x01, (__m128bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f}), -0.0f, 0.0f, 0.0f, 0.0f));

__m256 test_mm256_maskz_cvtpbh_ps(__mmask8 M, __m128bh A) {
// CHECK-LABEL: test_mm256_maskz_cvtpbh_ps
// CHECK: fpext <8 x bfloat> %{{.*}} to <8 x float>
// CHECK: select <8 x i1> %{{.*}}, <8 x float> %{{.*}}, <8 x float> %{{.*}}
return _mm256_maskz_cvtpbh_ps(M, A);
}
TEST_CONSTEXPR(match_m256(_mm256_maskz_cvtpbh_ps(0x73, (__m128bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f}), -0.0f, 1.0f, 0.0f, 0.0f, -8.0f, 16.0f, -32.0f, 0.0f));

__m128 test_mm_mask_cvtpbh_ps(__m128 S, __mmask8 M, __m128bh A) {
// CHECK-LABEL: test_mm_mask_cvtpbh_ps
Expand All @@ -189,10 +194,12 @@ __m128 test_mm_mask_cvtpbh_ps(__m128 S, __mmask8 M, __m128bh A) {
// CHECK: select <4 x i1> %{{.*}}, <4 x float> %{{.*}}, <4 x float> %{{.*}}
return _mm_mask_cvtpbh_ps(S, M, A);
}
TEST_CONSTEXPR(match_m128(_mm_mask_cvtpbh_ps((__m128){ 99.0f, 99.0f, 99.0f, 99.0f }, 0x03, (__m128bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f}), -0.0f, 1.0f, 99.0f, 99.0f));

__m256 test_mm256_mask_cvtpbh_ps(__m256 S, __mmask8 M, __m128bh A) {
// CHECK-LABEL: test_mm256_mask_cvtpbh_ps
// CHECK: fpext <8 x bfloat> %{{.*}} to <8 x float>
// CHECK: select <8 x i1> %{{.*}}, <8 x float> %{{.*}}, <8 x float> %{{.*}}
return _mm256_mask_cvtpbh_ps(S, M, A);
}
TEST_CONSTEXPR(match_m256(_mm256_mask_cvtpbh_ps((__m256){ 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f, 99.0f }, 0x37, (__m128bh){-0.0f, 1.0f, -2.0f, 4.0f, -8.0f, 16.0f, -32.0f, 64.0f}), -0.0f, 1.0f, -2.0f, 99.0f, -8.0f, 16.0f, 99.0f, 99.0f));
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