[PATCH] D158241: [llvm-libgcc] Don't export __{,de}register_frame_info* and __register_frame_table

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
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These symbols are used in the absence of PT_GNU_EH_FRAME, for ld
--no-eh-frame-hdr (gcc -static default).

libunwind defines these empty functions when
`defined(_LIBUNWIND_BUILD_ZERO_COST_APIS) && defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_SUPPORT_FRAME_APIS)`.
They should be perceived as Mac OS X workarounds.

For Linux, GCC crtbeginT.o (for -static) and clang_rt.crtbegin.o contain
undefined references to __{,de}register_frame_info. Dynamically linked
executables will either not reference __{,de}register_frame_info (using
libgcc) or reference them as weak symbols (using compiler-rt).

Therefore, not defining these symbols is backward compatible.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158241

Files:
  llvm-libgcc/lib/gcc_s.ver


Index: llvm-libgcc/lib/gcc_s.ver
===================================================================
--- llvm-libgcc/lib/gcc_s.ver
+++ llvm-libgcc/lib/gcc_s.ver
@@ -70,11 +70,6 @@
 #endif
 
 #if defined(GLOBAL_X86)
-  GCC_3.0 {
-    __deregister_frame_info_bases; __fixunsxfdi; __register_frame_info_bases;
-    __register_frame_info_table_bases;
-  };
-
   GCC_4.0.0 { __divxc3; __mulxc3; __powixf2; };
   GCC_4.8.0 { __cpu_indicator_init;          };
 #endif
@@ -148,17 +143,11 @@
 #if defined(__i386__)
   GCC_3.0   { __fixunsxfsi; __fixxfdi; __floatdixf; };
   GCC_4.2.0 { __floatundixf; };
-
-  GLIBC_2.0 {
-    __register_frame_info; __register_frame_info_table; __register_frame_table;
-    __deregister_frame_info;
-  };
 #endif
 
 #if defined(__x86_64__)
   GCC_3.0 {
-    __register_frame_info; __register_frame_info_table; __register_frame_table;
-    __deregister_frame;    __deregister_frame_info;     __register_frame;
+    __deregister_frame;    __register_frame;
     __fixunsxfti;          __fixxfti;                   __floattixf;
   };
 


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