[libc-commits] [libc] [libc] Proof of concept of aliasing long double math functions. (PR #132627)
via libc-commits
libc-commits at lists.llvm.org
Mon Mar 24 10:08:21 PDT 2025
https://github.com/lntue updated https://github.com/llvm/llvm-project/pull/132627
>From d53238e6e2d6b14b882ed000a5cf81480d4366ad Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Sun, 23 Mar 2025 17:57:21 +0000
Subject: [PATCH 1/5] [libc] Proof of concept of aliasing long double math
functions.
---
.../cmake/modules/LLVMLibCArchitectures.cmake | 1 +
.../modules/LLVMLibCCompileOptionRules.cmake | 2 ++
libc/src/math/CMakeLists.txt | 31 ++++++++++++++++---
libc/src/math/generic/copysign.cpp | 12 +++++++
libc/src/math/generic/copysignf128.cpp | 11 +++++++
libc/src/math/generic/copysignl.cpp | 7 +++++
6 files changed, 59 insertions(+), 5 deletions(-)
diff --git a/libc/cmake/modules/LLVMLibCArchitectures.cmake b/libc/cmake/modules/LLVMLibCArchitectures.cmake
index 62f3a2e3bdb59..5cdce54accdf3 100644
--- a/libc/cmake/modules/LLVMLibCArchitectures.cmake
+++ b/libc/cmake/modules/LLVMLibCArchitectures.cmake
@@ -150,6 +150,7 @@ if(LIBC_TARGET_ARCHITECTURE STREQUAL "arm")
set(LIBC_TARGET_ARCHITECTURE_IS_ARM TRUE)
elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "aarch64")
set(LIBC_TARGET_ARCHITECTURE_IS_AARCH64 TRUE)
+ set(LIBC_TARGET_LONG_DOUBLE_IS_FLOAT128 TRUE)
elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "x86_64")
set(LIBC_TARGET_ARCHITECTURE_IS_X86_64 TRUE)
elseif(LIBC_TARGET_ARCHITECTURE STREQUAL "i386")
diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 0facb0b9be0c1..b6fec2e687495 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -118,6 +118,8 @@ function(_get_common_compile_options output_var flags)
if(LLVM_LIBC_COMPILER_IS_GCC_COMPATIBLE)
list(APPEND compile_options "-fpie")
+ list(APPEND compile_options "-DLIBC_ALIAS_LONG_DOUBLE")
+
if(LLVM_LIBC_FULL_BUILD)
# Only add -ffreestanding flag in non-GPU full build mode.
if(NOT LIBC_TARGET_OS_IS_GPU)
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 92c80a1053c9e..42d028aa3d6cd 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -7,24 +7,31 @@ function(add_math_entrypoint_object name)
# We prefer machine specific implementation if available. Hence we check
# that first and return early if we are able to add an alias target for the
# machine specific implementation.
- get_fq_target_name("${LIBC_TARGET_ARCHITECTURE}.${name}" fq_machine_specific_target_name)
+ if(NOT ARGN)
+ set(alias_entrypoint ${name})
+ else()
+ message(STATUS "Banananana ${name} ${ARGN}")
+ set(alias_entrypoint ${ARGN})
+ endif()
+
+ get_fq_target_name("${LIBC_TARGET_ARCHITECTURE}.${alias_entrypoint}" fq_machine_specific_target_name)
if(TARGET ${fq_machine_specific_target_name})
add_entrypoint_object(
${name}
ALIAS
DEPENDS
- .${LIBC_TARGET_ARCHITECTURE}.${name}
+ .${LIBC_TARGET_ARCHITECTURE}.${alias_entrypoint}
)
return()
endif()
- get_fq_target_name("generic.${name}" fq_generic_target_name)
+ get_fq_target_name("generic.${alias_entrypoint}" fq_generic_target_name)
if(TARGET ${fq_generic_target_name})
add_entrypoint_object(
${name}
ALIAS
DEPENDS
- .generic.${name}
+ .generic.${alias_entrypoint}
)
return()
endif()
@@ -40,6 +47,20 @@ function(add_math_entrypoint_object name)
)
endfunction()
+function(add_long_double_math_entrypoint_object name)
+ get_fq_target_name(${name} fq_double_math_target)
+ get_fq_target_name("${name}l" fq_long_double_math_target)
+ get_fq_target_name("${name}f128" fq_float128_math_target)
+
+ if(LIBC_TARGET_LONG_DOUBLE_IS_DOUBLE)
+ add_math_entrypoint_object("${name}l" "${name}")
+ elseif(LIBC_TARGET_LONG_DOUBLE_IS_FLOAT128)
+ add_math_entrypoint_object("${name}l" "${name}f128")
+ else()
+ add_math_entrypoint_object("${name}l")
+ endif()
+endfunction()
+
add_math_entrypoint_object(acos)
add_math_entrypoint_object(acosf)
add_math_entrypoint_object(acosf16)
@@ -88,9 +109,9 @@ add_math_entrypoint_object(ceilf128)
add_math_entrypoint_object(copysign)
add_math_entrypoint_object(copysignf)
-add_math_entrypoint_object(copysignl)
add_math_entrypoint_object(copysignf16)
add_math_entrypoint_object(copysignf128)
+add_long_double_math_entrypoint_object(copysign)
add_math_entrypoint_object(cos)
add_math_entrypoint_object(cosf)
diff --git a/libc/src/math/generic/copysign.cpp b/libc/src/math/generic/copysign.cpp
index 186bb2c5983f4..6eed8b08044bf 100644
--- a/libc/src/math/generic/copysign.cpp
+++ b/libc/src/math/generic/copysign.cpp
@@ -10,6 +10,7 @@
#include "src/__support/FPUtil/ManipulationFunctions.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
namespace LIBC_NAMESPACE_DECL {
@@ -22,3 +23,14 @@ LLVM_LIBC_FUNCTION(double, copysign, (double x, double y)) {
}
} // namespace LIBC_NAMESPACE_DECL
+
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64) && \
+ defined(LIBC_ALIAS_LONG_DOUBLE)
+#include "src/math/copysignl.h"
+
+namespace LIBC_NAMESPACE_DECL {
+decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
+asm("copysignl = copysign");
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
\ No newline at end of file
diff --git a/libc/src/math/generic/copysignf128.cpp b/libc/src/math/generic/copysignf128.cpp
index 9a51c8d5eb8df..4101fd6764160 100644
--- a/libc/src/math/generic/copysignf128.cpp
+++ b/libc/src/math/generic/copysignf128.cpp
@@ -18,3 +18,14 @@ LLVM_LIBC_FUNCTION(float128, copysignf128, (float128 x, float128 y)) {
}
} // namespace LIBC_NAMESPACE_DECL
+
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128) && \
+ defined(LIBC_ALIAS_LONG_DOUBLE)
+#include "src/math/copysignl.h"
+
+namespace LIBC_NAMESPACE_DECL {
+decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
+asm("copysignl = copysignf128");
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128
\ No newline at end of file
diff --git a/libc/src/math/generic/copysignl.cpp b/libc/src/math/generic/copysignl.cpp
index 73c47bb04ad4a..d32680687a5d3 100644
--- a/libc/src/math/generic/copysignl.cpp
+++ b/libc/src/math/generic/copysignl.cpp
@@ -10,6 +10,11 @@
#include "src/__support/FPUtil/ManipulationFunctions.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+#if !(defined(LIBC_ALIAS_LONG_DOUBLE) && \
+ (defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64) || \
+ defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)))
namespace LIBC_NAMESPACE_DECL {
@@ -18,3 +23,5 @@ LLVM_LIBC_FUNCTION(long double, copysignl, (long double x, long double y)) {
}
} // namespace LIBC_NAMESPACE_DECL
+
+#endif
>From 124367173425eb37c1eac32a4d8f3b50fa946127 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Sun, 23 Mar 2025 18:23:35 +0000
Subject: [PATCH 2/5] Add new lines at the EOFs.
---
libc/src/math/generic/copysign.cpp | 2 +-
libc/src/math/generic/copysignf128.cpp | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/libc/src/math/generic/copysign.cpp b/libc/src/math/generic/copysign.cpp
index 6eed8b08044bf..cf46e72390442 100644
--- a/libc/src/math/generic/copysign.cpp
+++ b/libc/src/math/generic/copysign.cpp
@@ -33,4 +33,4 @@ decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
asm("copysignl = copysign");
} // namespace LIBC_NAMESPACE_DECL
-#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
\ No newline at end of file
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
diff --git a/libc/src/math/generic/copysignf128.cpp b/libc/src/math/generic/copysignf128.cpp
index 4101fd6764160..013cc95cb71b7 100644
--- a/libc/src/math/generic/copysignf128.cpp
+++ b/libc/src/math/generic/copysignf128.cpp
@@ -28,4 +28,4 @@ decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
asm("copysignl = copysignf128");
} // namespace LIBC_NAMESPACE_DECL
-#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128
\ No newline at end of file
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128
>From ed922b7df9113bd06c2f8cb37e98c3ca81ba6ec0 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Mon, 24 Mar 2025 16:58:45 +0000
Subject: [PATCH 3/5] Fix and create common aliasing macro.
---
.../modules/LLVMLibCCompileOptionRules.cmake | 4 +-
libc/src/__support/common.h | 44 +++++++++++++++----
libc/src/math/generic/copysign.cpp | 5 +--
libc/src/math/generic/copysignf128.cpp | 5 +--
libc/src/math/generic/copysignl.cpp | 7 ---
5 files changed, 40 insertions(+), 25 deletions(-)
diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index b6fec2e687495..d20bcc2fdb2cb 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -118,7 +118,9 @@ function(_get_common_compile_options output_var flags)
if(LLVM_LIBC_COMPILER_IS_GCC_COMPATIBLE)
list(APPEND compile_options "-fpie")
- list(APPEND compile_options "-DLIBC_ALIAS_LONG_DOUBLE")
+ if(LIBC_TARGET_LONG_DOUBLE_IS_FLOAT128 OR LIBC_TARGET_LONG_DOUBLE_IS_FLOAT64)
+ list(APPEND compile_options "-DLIBC_ALIAS_LONG_DOUBLE")
+ endif()
if(LLVM_LIBC_FULL_BUILD)
# Only add -ffreestanding flag in non-GPU full build mode.
diff --git a/libc/src/__support/common.h b/libc/src/__support/common.h
index 42e8a79187fac..af2409bdaf605 100644
--- a/libc/src/__support/common.h
+++ b/libc/src/__support/common.h
@@ -37,21 +37,47 @@
#define LLVM_LIBC_ATTR(name) EXPAND_THEN_SECOND(LLVM_LIBC_FUNCTION_ATTR_##name)
-// MacOS needs to be excluded because it does not support aliasing.
-#if defined(LIBC_COPT_PUBLIC_PACKAGING) && (!defined(__APPLE__))
-#define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) \
+// MacOS needs to be excluded because it does not support [[gnu::aliasing]].
+#ifndef __APPLE__
+
+#if defined(LIBC_COPT_PUBLIC_PACKAGING)
+#define LLVM_LIBC_FUNCTION(type, name, arglist) \
LLVM_LIBC_ATTR(name) \
LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) \
- __##name##_impl__ __asm__(#name); \
+ __##name##_impl__ asm(#name); \
decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#name)]]; \
type __##name##_impl__ arglist
-#else
-#define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) type name arglist
-#endif
-// This extra layer of macro allows `name` to be a macro to rename a function.
+#define LLVM_LIBC_ALIASING_FUNCTION(name, alias) \
+ namespace LIBC_NAMESPACE_DECL { \
+ decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#alias)]]; \
+ asm(#name " = " #alias) \
+ } \
+ static_assert(true, "Require semicolon")
+#else
#define LLVM_LIBC_FUNCTION(type, name, arglist) \
- LLVM_LIBC_FUNCTION_IMPL(type, name, arglist)
+ LLVM_LIBC_ATTR(name) \
+ LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) \
+ __##name##_impl__ asm("__" #name "_impl__"); \
+ decltype(LIBC_NAMESPACE::name) name [[gnu::alias("__" #name "_impl__")]]; \
+ type __##name##_impl__ arglist
+
+#define LLVM_LIBC_ALIASING_FUNCTION(name, alias) \
+ namespace LIBC_NAMESPACE_DECL { \
+ decltype(LIBC_NAMESPACE::name) name [[gnu::alias("__" #alias "_impl__")]]; \
+ asm(#name " = __" #alias "_impl__") \
+ } \
+ static_assert(true, "Require semicolon")
+#endif // LIBC_COPT_PUBLIC_PACKAGING
+
+#else
+
+#define LLVM_LIBC_FUNCTION(type, name, arglist) type name arglist
+
+#define LLVM_LIBC_ALIASING_FUNCTION(name, alias) \
+ static_assert(true, "Require semicolon")
+
+#endif // !__APPLE__
namespace LIBC_NAMESPACE_DECL {
namespace internal {
diff --git a/libc/src/math/generic/copysign.cpp b/libc/src/math/generic/copysign.cpp
index cf46e72390442..fef1d1f9ad332 100644
--- a/libc/src/math/generic/copysign.cpp
+++ b/libc/src/math/generic/copysign.cpp
@@ -28,9 +28,6 @@ LLVM_LIBC_FUNCTION(double, copysign, (double x, double y)) {
defined(LIBC_ALIAS_LONG_DOUBLE)
#include "src/math/copysignl.h"
-namespace LIBC_NAMESPACE_DECL {
-decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
-asm("copysignl = copysign");
-} // namespace LIBC_NAMESPACE_DECL
+LLVM_LIBC_ALIASING_FUNCTION(copysignl, copysign);
#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
diff --git a/libc/src/math/generic/copysignf128.cpp b/libc/src/math/generic/copysignf128.cpp
index 013cc95cb71b7..7130d55b97f34 100644
--- a/libc/src/math/generic/copysignf128.cpp
+++ b/libc/src/math/generic/copysignf128.cpp
@@ -23,9 +23,6 @@ LLVM_LIBC_FUNCTION(float128, copysignf128, (float128 x, float128 y)) {
defined(LIBC_ALIAS_LONG_DOUBLE)
#include "src/math/copysignl.h"
-namespace LIBC_NAMESPACE_DECL {
-decltype(LIBC_NAMESPACE::copysignl) copysignl [[gnu::alias("copysignl")]];
-asm("copysignl = copysignf128");
-} // namespace LIBC_NAMESPACE_DECL
+LLVM_LIBC_ALIASING_FUNCTION(copysignl, copysignf128);
#endif // LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128
diff --git a/libc/src/math/generic/copysignl.cpp b/libc/src/math/generic/copysignl.cpp
index d32680687a5d3..73c47bb04ad4a 100644
--- a/libc/src/math/generic/copysignl.cpp
+++ b/libc/src/math/generic/copysignl.cpp
@@ -10,11 +10,6 @@
#include "src/__support/FPUtil/ManipulationFunctions.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
-#include "src/__support/macros/properties/types.h"
-
-#if !(defined(LIBC_ALIAS_LONG_DOUBLE) && \
- (defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64) || \
- defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)))
namespace LIBC_NAMESPACE_DECL {
@@ -23,5 +18,3 @@ LLVM_LIBC_FUNCTION(long double, copysignl, (long double x, long double y)) {
}
} // namespace LIBC_NAMESPACE_DECL
-
-#endif
>From 8e1abc1a334a57b13e65318c6a74c805a227347b Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Mon, 24 Mar 2025 17:01:26 +0000
Subject: [PATCH 4/5] Remove debugging message.
---
libc/src/math/CMakeLists.txt | 1 -
1 file changed, 1 deletion(-)
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 42d028aa3d6cd..c86b98c65a6c8 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -10,7 +10,6 @@ function(add_math_entrypoint_object name)
if(NOT ARGN)
set(alias_entrypoint ${name})
else()
- message(STATUS "Banananana ${name} ${ARGN}")
set(alias_entrypoint ${ARGN})
endif()
>From 268dd921857f3edb85e68792f377395cfba6c3b8 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue.h at gmail.com>
Date: Mon, 24 Mar 2025 17:07:56 +0000
Subject: [PATCH 5/5] Add missing semicolons.
---
libc/src/__support/common.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libc/src/__support/common.h b/libc/src/__support/common.h
index af2409bdaf605..4582a43adf74f 100644
--- a/libc/src/__support/common.h
+++ b/libc/src/__support/common.h
@@ -51,7 +51,7 @@
#define LLVM_LIBC_ALIASING_FUNCTION(name, alias) \
namespace LIBC_NAMESPACE_DECL { \
decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#alias)]]; \
- asm(#name " = " #alias) \
+ asm(#name " = " #alias); \
} \
static_assert(true, "Require semicolon")
#else
@@ -65,7 +65,7 @@
#define LLVM_LIBC_ALIASING_FUNCTION(name, alias) \
namespace LIBC_NAMESPACE_DECL { \
decltype(LIBC_NAMESPACE::name) name [[gnu::alias("__" #alias "_impl__")]]; \
- asm(#name " = __" #alias "_impl__") \
+ asm(#name " = __" #alias "_impl__"); \
} \
static_assert(true, "Require semicolon")
#endif // LIBC_COPT_PUBLIC_PACKAGING
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