commit 8d5fb6f1dd53c7cb8fda272eb70f45ac718fc671
author Ryan Prichard <rprichard@google.com> Mon Feb 22 16:35:38 2021 -0800
committer Copybara-Service <copybara-worker@google.com> Mon Feb 22 16:56:02 2021 -0800
tree 67eb0714a04847553d7e4d55253b18544dad92b3
parent a2cc4f8c554dedcb0c64cac5511b19c43f1f3d32

[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

src/assembly.h

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)