[libc-commits] [libc] [libc] Allow LLVM_LIBC_FUNCTION macro to take another parameter for function alias. (PR #187154)
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libc-commits at lists.llvm.org
Wed Mar 18 09:21:54 PDT 2026
https://github.com/lntue updated https://github.com/llvm/llvm-project/pull/187154
>From e849d07c709ed8866db29e99b4b98e3e10615490 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Tue, 17 Mar 2026 23:27:03 +0000
Subject: [PATCH 1/2] [libc] Allow LLVM_LIBC_FUNCTION macro to take another
parameter for function alias.
---
libc/src/__support/common.h | 28 +++++++++++++++++++---------
libc/src/mathvec/generic/expf.cpp | 6 +++++-
2 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/libc/src/__support/common.h b/libc/src/__support/common.h
index da157a8646458..b3bbb08d4ed2f 100644
--- a/libc/src/__support/common.h
+++ b/libc/src/__support/common.h
@@ -37,7 +37,9 @@
// clang-format on
#define LLVM_LIBC_EMPTY
+#define GET_NOTHING(...) 0
#define GET_SECOND(first, second, ...) second
+#define GET_FIFTH(first, second, third, fourth, fifth, ...) fifth
#define EXPAND_THEN_SECOND(name) GET_SECOND(name, LLVM_LIBC_EMPTY)
#define LLVM_LIBC_ATTR(name) EXPAND_THEN_SECOND(LLVM_LIBC_FUNCTION_ATTR_##name)
@@ -48,25 +50,33 @@
// symbol. Moreover, a C symbol `func` in macOS is mangled as `_func`.
#if defined(LIBC_COPT_PUBLIC_PACKAGING) && !defined(LIBC_COMPILER_IS_MSVC)
#ifndef __APPLE__
-#define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) \
+#define LLVM_LIBC_FUNCTION_IMPL_4(type, name, arglist, c_alias) \
LLVM_LIBC_ATTR(name) \
LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) \
- __##name##_impl__ asm(#name); \
- decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#name)]]; \
+ __##name##_impl__ asm(c_alias); \
+ decltype(LIBC_NAMESPACE::name) name [[gnu::alias(c_alias)]]; \
type __##name##_impl__ arglist
#else // __APPLE__
-#define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) \
+#define LLVM_LIBC_FUNCTION_IMPL_4(type, name, arglist, c_alias) \
LLVM_LIBC_ATTR(name) \
- LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) name asm("_" #name); \
+ LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) name asm( \
+ "_" c_alias); \
type name arglist
#endif // __APPLE__
+
#else // LIBC_COPT_PUBLIC_PACKAGING
-#define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) type name arglist
+#define LLVM_LIBC_FUNCTION_IMPL_4(type, name, arglist, c_alias) \
+ type name arglist
#endif // LIBC_COPT_PUBLIC_PACKAGING
-// This extra layer of macro allows `name` to be a macro to rename a function.
-#define LLVM_LIBC_FUNCTION(type, name, arglist) \
- LLVM_LIBC_FUNCTION_IMPL(type, name, arglist)
+#define LLVM_LIBC_FUNCTION_IMPL_3(type, name, arglist) \
+ LLVM_LIBC_FUNCTION_IMPL_4(type, name, arglist, #name)
+
+// LLVM_LIBC_FUNCTION(type, name, arglist) is equivalent to
+// LLVM_LIBC_FUNCTION(type, name, arglist, #name)
+#define LLVM_LIBC_FUNCTION(...) \
+ GET_FIFTH(__VA_ARGS__, LLVM_LIBC_FUNCTION_IMPL_4, LLVM_LIBC_FUNCTION_IMPL_3, \
+ GET_NOTHING)(__VA_ARGS__)
// At the moment, [[gnu::alias()]] is not supported on MacOS, and it is needed
// to cleanly export and alias the C++ symbol `LIBC_NAMESPACE::func` with the C
diff --git a/libc/src/mathvec/generic/expf.cpp b/libc/src/mathvec/generic/expf.cpp
index d86c21d40644c..7db8838e00bf8 100644
--- a/libc/src/mathvec/generic/expf.cpp
+++ b/libc/src/mathvec/generic/expf.cpp
@@ -7,10 +7,14 @@
//===----------------------------------------------------------------------===//
#include "src/mathvec/expf.h"
+#include "src/__support/common.h"
#include "src/__support/mathvec/expf.h"
namespace LIBC_NAMESPACE_DECL {
-cpp::simd<float> expf(cpp::simd<float> x) { return mathvec::expf(x); }
+LLVM_LIBC_FUNCTION(cpp::simd<float>, expf, (cpp::simd<float> x),
+ "_ZGVbN4v_expf") {
+ return mathvec::expf(x);
+}
} // namespace LIBC_NAMESPACE_DECL
>From 42076c74872c933da684ef254fca8b05cfacd40f Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Wed, 18 Mar 2026 16:21:05 +0000
Subject: [PATCH 2/2] Add proper default names for vectorized expf.
---
libc/src/mathvec/generic/CMakeLists.txt | 1 +
libc/src/mathvec/generic/expf.cpp | 21 ++++++++++++++++++++-
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/libc/src/mathvec/generic/CMakeLists.txt b/libc/src/mathvec/generic/CMakeLists.txt
index c2abbfbe265ca..d5d94d5ed56b5 100644
--- a/libc/src/mathvec/generic/CMakeLists.txt
+++ b/libc/src/mathvec/generic/CMakeLists.txt
@@ -5,6 +5,7 @@ add_entrypoint_object(
HDRS
../expf.h
DEPENDS
+ libc.src.__support.macros.properties.cpu_features
libc.src.__support.mathvec.expf
FLAGS
ROUND_OPT
diff --git a/libc/src/mathvec/generic/expf.cpp b/libc/src/mathvec/generic/expf.cpp
index 7db8838e00bf8..e269fa82e08f5 100644
--- a/libc/src/mathvec/generic/expf.cpp
+++ b/libc/src/mathvec/generic/expf.cpp
@@ -8,12 +8,31 @@
#include "src/mathvec/expf.h"
#include "src/__support/common.h"
+#include "src/__support/macros/properties/cpu_features.h"
#include "src/__support/mathvec/expf.h"
+#ifndef LIBC_MATHVEC_EXPF_SYM
+#if defined(LIBC_TARGET_CPU_HAS_AVX512F)
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "_ZGVeN16v_"
+#elif defined(LIBC_TARGET_CPU_HAS_AVX2)
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "_ZGVdN8v_"
+#elif defined(LIBC_TARGET_CPU_HAS_AVX)
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "_ZGVcN8v_"
+#elif defined(LIBC_TARGET_CPU_HAS_SSE2)
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "_ZGVbN4v_"
+#elif defined(LIBC_TARGET_CPU_HAS_ARM_NEON)
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "_ZGVnN4v_"
+#else
+#define LIBC_MATHVEC_EXPF_SYM_PREFIX "__"
+#endif // LIBC_TARGET_CPU_HAS_*
+
+#define LIBC_MATHVEC_EXPF_SYM LIBC_MATHVEC_EXPF_SYM_PREFIX "expf"
+#endif // LIBC_MATHVEC_EXPF_SYM
+
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(cpp::simd<float>, expf, (cpp::simd<float> x),
- "_ZGVbN4v_expf") {
+ LIBC_MATHVEC_EXPF_SYM) {
return mathvec::expf(x);
}
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