[libunwind] 5eb44df - Make _LIBUNWIND_SUPPORT_FRAME_APIS a build-time option

[Sterling Augustine via cfe-commits]

Author: Sterling Augustine
Date: 2023-08-23T14:34:40-07:00
New Revision: 5eb44df1b64dbd1a86b099128092a7fd2001c0ba

URL: https://github.com/llvm/llvm-project/commit/5eb44df1b64dbd1a86b099128092a7fd2001c0ba
DIFF: https://github.com/llvm/llvm-project/commit/5eb44df1b64dbd1a86b099128092a7fd2001c0ba.diff

LOG: Make _LIBUNWIND_SUPPORT_FRAME_APIS a build-time option

Previously this was based on target architecture, but
that makes very little sense--frame API availability is generally
for libgcc compatibility and that is dependent on runtime
needs rather than target architecture.

Default this to on, so as not to remove the apis from
environments that already have them.

The functions this macro protects are stubs for libgcc-compatibility.
Today, libunwind as a drop-in replacement for libgcc_eh links on x86,
x86_64, and powerpc, but not aarch64, which doesn't really make
sense. As there is nothing architecture specific about these, they
should be provided everywhere or nowhere.

The target-specific protection goes all the way back to the original
code contribution in 312fcd0e1cf14482b2ae8eee8234541dcc3bc2c4 from
2013, so the original reason is lost to history, and probably not
relevant today.

Differential Revision: https://reviews.llvm.org/D158011

Added: 
    

Modified: 
    libunwind/CMakeLists.txt
    libunwind/src/config.h

Removed: 
    


################################################################################
diff  --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
index bc2a820fe98ebb..84f8ce296a7410 100644
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -51,6 +51,7 @@ option(LIBUNWIND_IS_BAREMETAL "Build libunwind for baremetal targets." OFF)
 option(LIBUNWIND_USE_FRAME_HEADER_CACHE "Cache frame headers for unwinding. Requires locking dl_iterate_phdr." OFF)
 option(LIBUNWIND_REMEMBER_HEAP_ALLOC "Use heap instead of the stack for .cfi_remember_state." OFF)
 option(LIBUNWIND_INSTALL_HEADERS "Install the libunwind headers." ON)
+option(LIBUNWIND_ENABLE_FRAME_APIS "Include libgcc-compatible frame apis." OFF)
 
 set(LIBUNWIND_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
@@ -250,6 +251,11 @@ if (NOT LIBUNWIND_ENABLE_CROSS_UNWINDING)
   add_compile_flags(-D_LIBUNWIND_IS_NATIVE_ONLY)
 endif()
 
+# Include stubs for __register_frame_info_bases and related
+if (LIBUNWIND_ENABLE_FRAME_APIS)
+  add_compile_flags(-D_LIBUNWIND_SUPPORT_FRAME_APIS)
+endif()
+
 # Threading-support
 if (NOT LIBUNWIND_ENABLE_THREADS)
   add_compile_flags(-D_LIBUNWIND_HAS_NO_THREADS)

diff  --git a/libunwind/src/config.h b/libunwind/src/config.h
index 6707d591361dfc..ef6b8d67181b4e 100644
--- a/libunwind/src/config.h
+++ b/libunwind/src/config.h
@@ -108,10 +108,6 @@
 #define _LIBUNWIND_BUILD_SJLJ_APIS
 #endif
 
-#if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__)
-#define _LIBUNWIND_SUPPORT_FRAME_APIS
-#endif
-
 #if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__) ||        \
     (!defined(__APPLE__) && defined(__arm__)) || defined(__aarch64__) ||       \
     defined(__mips__) || defined(__riscv) || defined(__hexagon__) ||           \