[libunwind] unw_* alias fixes for ELF and Mach-O
Rename the CMake option, LIBUNWIND_HERMETIC_STATIC_LIBRARY, to
LIBUNWIND_HIDE_SYMBOLS. Rename the C macro define,
_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS, to _LIBUNWIND_HIDE_SYMBOLS,
because now the macro adds a .hidden directive rather than merely
suppress visibility annotations.
For ELF, when LIBUNWIND_HIDE_SYMBOLS is enabled, mark unw_getcontext as
hidden. This symbol is the only one defined using src/assembly.h's
WEAK_ALIAS macro. Other unw_* weak aliases are defined in C++ and are
already hidden.
Mach-O doesn't support weak aliases, so remove .weak_reference and
weak_import. When LIBUNWIND_HIDE_SYMBOLS is enabled, output
.private_extern for the unw_* aliases.
In assembly.h, add missing SYMBOL_NAME macro invocations, which are
used to prefix symbol names with '_' on some targets.
Fixes PR46709.
Reviewed By: #libunwind, phosek, compnerd, steven_wu
Differential Revision: https://reviews.llvm.org/D93003
GitOrigin-RevId: 729899f7b6bf6aff65988d895d7a639391a67608
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index a7045d2..f59dfdd 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -164,11 +164,11 @@
LINKER_LANGUAGE C
OUTPUT_NAME "unwind")
- if(LIBUNWIND_HERMETIC_STATIC_LIBRARY)
+ if(LIBUNWIND_HIDE_SYMBOLS)
append_flags_if_supported(UNWIND_STATIC_LIBRARY_FLAGS -fvisibility=hidden)
append_flags_if_supported(UNWIND_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
target_compile_options(unwind_static PRIVATE ${UNWIND_STATIC_LIBRARY_FLAGS})
- target_compile_definitions(unwind_static PRIVATE _LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS)
+ target_compile_definitions(unwind_static PRIVATE _LIBUNWIND_HIDE_SYMBOLS)
endif()
list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_static")
diff --git a/src/assembly.h b/src/assembly.h
index f2f7c84..dcd3819 100644
--- a/src/assembly.h
+++ b/src/assembly.h
@@ -70,12 +70,15 @@
#if defined(__APPLE__)
#define SYMBOL_IS_FUNC(name)
-#define EXPORT_SYMBOL(name)
#define HIDDEN_SYMBOL(name) .private_extern name
-#define WEAK_SYMBOL(name) .weak_reference name
+#if defined(_LIBUNWIND_HIDE_SYMBOLS)
+#define EXPORT_SYMBOL(name) HIDDEN_SYMBOL(name)
+#else
+#define EXPORT_SYMBOL(name)
+#endif
#define WEAK_ALIAS(name, aliasname) \
.globl SYMBOL_NAME(aliasname) SEPARATOR \
- WEAK_SYMBOL(aliasname) SEPARATOR \
+ EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
#define NO_EXEC_STACK_DIRECTIVE
@@ -87,17 +90,23 @@
#else
#define SYMBOL_IS_FUNC(name) .type name,@function
#endif
-#define EXPORT_SYMBOL(name)
#define HIDDEN_SYMBOL(name) .hidden name
+#if defined(_LIBUNWIND_HIDE_SYMBOLS)
+#define EXPORT_SYMBOL(name) HIDDEN_SYMBOL(name)
+#else
+#define EXPORT_SYMBOL(name)
+#endif
#define WEAK_SYMBOL(name) .weak name
#if defined(__hexagon__)
-#define WEAK_ALIAS(name, aliasname) \
- WEAK_SYMBOL(aliasname) SEPARATOR \
+#define WEAK_ALIAS(name, aliasname) \
+ EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
+ WEAK_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
.equiv SYMBOL_NAME(aliasname), SYMBOL_NAME(name)
#else
#define WEAK_ALIAS(name, aliasname) \
- WEAK_SYMBOL(aliasname) SEPARATOR \
+ EXPORT_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
+ WEAK_SYMBOL(SYMBOL_NAME(aliasname)) SEPARATOR \
SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
#endif
@@ -119,7 +128,7 @@
.section .drectve,"yn" SEPARATOR \
.ascii "-export:", #name, "\0" SEPARATOR \
.text
-#if defined(_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS)
+#if defined(_LIBUNWIND_HIDE_SYMBOLS)
#define EXPORT_SYMBOL(name)
#else
#define EXPORT_SYMBOL(name) EXPORT_SYMBOL2(name)
diff --git a/src/config.h b/src/config.h
index 9efed05..5b860dc 100644
--- a/src/config.h
+++ b/src/config.h
@@ -52,7 +52,8 @@
#endif
#endif
-#if defined(_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS)
+#if defined(_LIBUNWIND_HIDE_SYMBOLS)
+ // The CMake file passes -fvisibility=hidden to control ELF/Mach-O visibility.
#define _LIBUNWIND_EXPORT
#define _LIBUNWIND_HIDDEN
#else
@@ -70,11 +71,15 @@
#define SYMBOL_NAME(name) XSTR(__USER_LABEL_PREFIX__) #name
#if defined(__APPLE__)
+#if defined(_LIBUNWIND_HIDE_SYMBOLS)
+#define _LIBUNWIND_ALIAS_VISIBILITY(name) __asm__(".private_extern " name)
+#else
+#define _LIBUNWIND_ALIAS_VISIBILITY(name)
+#endif
#define _LIBUNWIND_WEAK_ALIAS(name, aliasname) \
__asm__(".globl " SYMBOL_NAME(aliasname)); \
__asm__(SYMBOL_NAME(aliasname) " = " SYMBOL_NAME(name)); \
- extern "C" _LIBUNWIND_EXPORT __typeof(name) aliasname \
- __attribute__((weak_import));
+ _LIBUNWIND_ALIAS_VISIBILITY(SYMBOL_NAME(aliasname));
#elif defined(__ELF__)
#define _LIBUNWIND_WEAK_ALIAS(name, aliasname) \
extern "C" _LIBUNWIND_EXPORT __typeof(name) aliasname \