PR go/64999

	PR go/65180
runtime: Adjust libbacktrace PC value to what runtime.Callers expects.

From Lynn Boger.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-5-branch@222197 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 14 insertions, 1 deletions

diff --git a/libgo/runtime/go-callers.c b/libgo/runtime/go-callers.c
index 34a21188e3a..b5ab3be6473 100644
--- a/libgo/runtime/go-callers.c
+++ b/libgo/runtime/go-callers.c
@@ -83,7 +83,20 @@ callback (void *data, uintptr_t pc, const char *filename, int lineno,
     }
 
   loc = &arg->locbuf[arg->index];
-  loc->pc = pc;
+
+  /* On the call to backtrace_full the pc value was most likely
+     decremented if there was a normal call, since the pc referred to
+     the instruction where the call returned and not the call itself.
+     This was done so that the line number referred to the call
+     instruction.  To make sure the actual pc from the call stack is
+     used, it is incremented here.
+
+     In the case of a signal, the pc was not decremented by
+     backtrace_full but still incremented here.  That doesn't really
+     hurt anything since the line number is right and the pc refers to
+     the same instruction.  */
+
+  loc->pc = pc + 1;
 
   /* The libbacktrace library says that these strings might disappear,
      but with the current implementation they won't.  We can't easily