Skip to content

[libc] Update some __builtin_* usage to be compatible with MSVC. #157870

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Sep 10, 2025
Merged

[libc] Update some __builtin_* usage to be compatible with MSVC. #157870

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
6294d91
[libc] Update some __builtin_* usage to be compatible with MSVC.
lntue Sep 10, 2025
62ee732
Fix __builtin_expect.
lntue Sep 10, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
22 changes: 20 additions & 2 deletions libc/src/__support/CPP/bit.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -104,10 +104,16 @@ countr_zero(T value) {
}
#if __has_builtin(__builtin_ctzs)
ADD_SPECIALIZATION(countr_zero, unsigned short, __builtin_ctzs)
#endif
#endif // __has_builtin(__builtin_ctzs)
#if __has_builtin(__builtin_ctz)
ADD_SPECIALIZATION(countr_zero, unsigned int, __builtin_ctz)
#endif // __has_builtin(__builtin_ctz)
#if __has_builtin(__builtin_ctzl)
ADD_SPECIALIZATION(countr_zero, unsigned long, __builtin_ctzl)
#endif // __has_builtin(__builtin_ctzl)
#if __has_builtin(__builtin_ctzll)
ADD_SPECIALIZATION(countr_zero, unsigned long long, __builtin_ctzll)
#endif // __has_builtin(__builtin_ctzll)
#endif // __has_builtin(__builtin_ctzg)

/// Count number of 0's from the most significant bit to the least
Expand Down Expand Up @@ -143,10 +149,16 @@ countl_zero(T value) {
}
#if __has_builtin(__builtin_clzs)
ADD_SPECIALIZATION(countl_zero, unsigned short, __builtin_clzs)
#endif
#endif // __has_builtin(__builtin_clzs)
#if __has_builtin(__builtin_clz)
ADD_SPECIALIZATION(countl_zero, unsigned int, __builtin_clz)
#endif // __has_builtin(__builtin_clz)
#if __has_builtin(__builtin_clzl)
ADD_SPECIALIZATION(countl_zero, unsigned long, __builtin_clzl)
#endif // __has_builtin(__builtin_clzl)
#if __has_builtin(__builtin_clzll)
ADD_SPECIALIZATION(countl_zero, unsigned long long, __builtin_clzll)
#endif // __has_builtin(__builtin_clzll)
#endif // __has_builtin(__builtin_clzg)

#undef ADD_SPECIALIZATION
Expand Down Expand Up @@ -283,11 +295,17 @@ popcount(T value) {
[[nodiscard]] LIBC_INLINE constexpr int popcount<TYPE>(TYPE value) { \
return BUILTIN(value); \
}
#if __has_builtin(__builtin_popcount)
ADD_SPECIALIZATION(unsigned char, __builtin_popcount)
ADD_SPECIALIZATION(unsigned short, __builtin_popcount)
ADD_SPECIALIZATION(unsigned, __builtin_popcount)
#endif // __builtin_popcount
#if __has_builtin(__builtin_popcountl)
ADD_SPECIALIZATION(unsigned long, __builtin_popcountl)
#endif // __builtin_popcountl
#if __has_builtin(__builtin_popcountll)
ADD_SPECIALIZATION(unsigned long long, __builtin_popcountll)
#endif // __builtin_popcountll
#endif // __builtin_popcountg
#undef ADD_SPECIALIZATION

Expand Down
3 changes: 3 additions & 0 deletions libc/src/__support/macros/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@ add_header_library(
config
HDRS
config.h
DEPENDS
libc.src.__support.macros.properties.architectures
libc.src.__support.macros.properties.compiler
)

add_header_library(
Expand Down
20 changes: 20 additions & 0 deletions libc/src/__support/macros/config.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,13 @@
#ifndef LLVM_LIBC_SRC___SUPPORT_MACROS_CONFIG_H
#define LLVM_LIBC_SRC___SUPPORT_MACROS_CONFIG_H

#include "src/__support/macros/properties/architectures.h"
#include "src/__support/macros/properties/compiler.h"

#ifdef LIBC_COMPILER_IS_MSVC
#include <intrin.h>
#endif // LIBC_COMPILER_IS_MSVC

// Workaround for compilers that do not support builtin detection.
// FIXME: This is only required for the GPU portion which should be moved.
#ifndef __has_builtin
Expand All @@ -27,6 +34,19 @@
#define LIBC_HAS_FEATURE(f) 0
#endif

#ifdef LIBC_COMPILER_IS_MSVC

// __builtin_trap replacement
#ifdef LIBC_TARGET_ARCH_IS_X86
#define __builtin_trap __ud2
#else // arm64
#define __builtin_trap() __break(1)
#endif

#define __builtin_expect(value, expectation) (value)

#endif // LIBC_COMPILER_IS_MSVC

#ifdef __clang__
// Declare a LIBC_NAMESPACE with hidden visibility. `namespace
// LIBC_NAMESPACE_DECL {` should be used around all declarations and definitions
Expand Down
4 changes: 4 additions & 0 deletions utils/bazel/llvm-project-overlay/libc/BUILD.bazel
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,10 @@ libc_support_library(
libc_support_library(
name = "__support_macros_config",
hdrs = ["src/__support/macros/config.h"],
deps = [
"__support_macros_properties_architectures",
"__support_macros_properties_compiler",
],
)

################################# Include Files ################################
Expand Down
Loading