[llvm-commits] [compiler-rt] r171973 - /compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc

[Kostya Serebryany]

Author: kcc
Date: Wed Jan  9 07:55:00 2013
New Revision: 171973

URL: http://llvm.org/viewvc/llvm-project?rev=171973&view=rev
Log:
[asan] make the slow unwinder a bit more robust. The unittests pass with fast_unwind_on_fatal=0, but I still observe some differences between the two unwinders

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=171973&r1=171972&r2=171973&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc Wed Jan  9 07:55:00 2013
@@ -413,7 +413,7 @@
 }
 
 static bool MatchPc(uptr cur_pc, uptr trace_pc) {
-  return cur_pc - trace_pc <= 8;
+  return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
 }
 
 void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
@@ -421,12 +421,14 @@
   this->max_size = max_depth;
   if (max_depth > 1) {
     _Unwind_Backtrace(Unwind_Trace, this);
-    // We need to pop a few (up to 3) frames so that pc is on top.
-    // trace[0] belongs to the current function.
+    // We need to pop a few frames so that pc is on top.
+    // trace[0] belongs to the current function so we always pop it.
     int to_pop = 1;
-    /**/ if (size >= 2 && MatchPc(pc, trace[1])) to_pop = 2;
-    else if (size >= 3 && MatchPc(pc, trace[2])) to_pop = 3;
-    else if (size >= 4 && MatchPc(pc, trace[3])) to_pop = 4;
+    /**/ if (size > 1 && MatchPc(pc, trace[1])) to_pop = 1;
+    else if (size > 2 && MatchPc(pc, trace[2])) to_pop = 2;
+    else if (size > 3 && MatchPc(pc, trace[3])) to_pop = 3;
+    else if (size > 4 && MatchPc(pc, trace[4])) to_pop = 4;
+    else if (size > 5 && MatchPc(pc, trace[5])) to_pop = 5;
     this->PopStackFrames(to_pop);
   }
   this->trace[0] = pc;