[compiler-rt] r192196 - [sanitizer] Do not break the CFI unwind chain in clone().

[Sergey Matveev]

Author: smatveev
Date: Tue Oct  8 11:38:39 2013
New Revision: 192196

URL: http://llvm.org/viewvc/llvm-project?rev=192196&view=rev
Log:
[sanitizer] Do not break the CFI unwind chain in clone().

Fixes build on clang 3.2, which doesn't support cfi_undefined. This change
doesn't seem to break the slow unwinder. Even if it does, the worst thing that
could happen is that we would not see a backtrace when a fatal error happens
under StopTheWorld.

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc?rev=192196&r1=192195&r2=192196&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc Tue Oct  8 11:38:39 2013
@@ -787,7 +787,6 @@ uptr internal_clone(int (*fn)(void *), v
                         */
                        "movq   %6,%%r8\n"
                        "movq   %7,%%r10\n"
-                       ".cfi_endproc\n"
                        "syscall\n"
 
                        /* if (%rax != 0)
@@ -797,8 +796,9 @@ uptr internal_clone(int (*fn)(void *), v
                        "jnz    1f\n"
 
                        /* In the child. Terminate unwind chain. */
-                       ".cfi_startproc\n"
-                       ".cfi_undefined %%rip;\n"
+                       // XXX: We should also terminate the CFI unwind chain
+                       // here. Unfortunately clang 3.2 doesn't support the
+                       // necessary CFI directives, so we skip that part.
                        "xorq   %%rbp,%%rbp\n"
 
                        /* Call "fn(arg)". */