[compiler-rt] 062cfad - [builtins] Disable COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY by default (#83201)

[via llvm-commits]

Author: Fangrui Song
Date: 2024-02-27T16:32:53-08:00
New Revision: 062cfada643c1aa48a1bb81894e2920d390fe8cf

URL: https://github.com/llvm/llvm-project/commit/062cfada643c1aa48a1bb81894e2920d390fe8cf
DIFF: https://github.com/llvm/llvm-project/commit/062cfada643c1aa48a1bb81894e2920d390fe8cf.diff

LOG: [builtins] Disable COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY by default (#83201)

Most of GCC's Linux targets have a link spec
`%{!static|static-pie:--eh-frame-hdr}` that doesn't pass --eh-frame-hdr
for `-static` links. `-static` links are supposed to utilize
`__register_frame_info` (called by `crtbeginT.o`, not by crtbegin.o or
crtbeginS.o) as a replacement.

compiler-rt crtbegin (not used with GCC) has some ehframe code, which is
not utilized because Clang driver unconditionally passes --eh-frame-hdr
for Linux targets, even for -static. In addition, LLVM libunwind
implements `__register_frame_info` as an empty stub.

Furthermore, in a non-static link, the `__register_frame_info`
references can cause an undesired weak dynamic symbol.

For now, just disable the config by default.

Added: 
    

Modified: 
    compiler-rt/lib/builtins/CMakeLists.txt
    compiler-rt/test/builtins/Unit/ctor_dtor.c

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 28ded8766f2533..83f7697a4a2b42 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -916,7 +916,7 @@ cmake_dependent_option(COMPILER_RT_BUILD_CRT "Build crtbegin.o/crtend.o" ON "COM
 if (COMPILER_RT_BUILD_CRT)
   add_compiler_rt_component(crt)
 
-  option(COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY "Use eh_frame in crtbegin.o/crtend.o" ON)
+  option(COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY "Use eh_frame in crtbegin.o/crtend.o" OFF)
 
   include(CheckSectionExists)
   check_section_exists(".init_array" COMPILER_RT_HAS_INITFINI_ARRAY

diff  --git a/compiler-rt/test/builtins/Unit/ctor_dtor.c b/compiler-rt/test/builtins/Unit/ctor_dtor.c
index 47560722a9f750..3d5f895a0a1cd1 100644
--- a/compiler-rt/test/builtins/Unit/ctor_dtor.c
+++ b/compiler-rt/test/builtins/Unit/ctor_dtor.c
@@ -9,23 +9,13 @@
 
 // Ensure the various startup functions are called in the proper order.
 
-// CHECK: __register_frame_info()
 /// ctor() is here if ld.so/libc supports DT_INIT/DT_FINI
 // CHECK:      main()
 /// dtor() is here if ld.so/libc supports DT_INIT/DT_FINI
-// CHECK:      __deregister_frame_info()
 
 struct object;
 static int counter;
 
-void __register_frame_info(const void *fi, struct object *obj) {
-  printf("__register_frame_info()\n");
-}
-
-void __deregister_frame_info(const void *fi) {
-  printf("__deregister_frame_info()\n");
-}
-
 void __attribute__((constructor)) ctor() {
   printf("ctor()\n");
   ++counter;