diff mbox

Go patch committed: Disable sibling calls by default

Message ID mcrvbyuiyyx.fsf@iant-glaptop.roam.corp.google.com
State New
Headers show

Commit Message

Ian Lance Taylor Dec. 12, 2013, 2:29 a.m. UTC 
Go programs expect to be able to call runtime.Callers to get their call
stack.  The libbacktrace library currently can not handle tail calls,
and it's not clear that it can ever be completely reliable in handling
tail calls.  This patch to the Go frontend disables tail call
optimization, unless it is specifically requested.  This will permit Go
programs that call runtime.Callers to work as expected.  Bootstrapped
and ran Go testsuite on x86_64-unknown-linux-gnu.  Committed to mainline
and 4.8 branch.

Ian


2013-12-11  Ian Lance Taylor  <iant@google.com>

	* go-lang.c (go_langhook_post_options): Disable sibling calls by
	default.
diff mbox

Patch

Index: go-lang.c
===================================================================
--- go-lang.c	(revision 205872)
+++ go-lang.c	(working copy)
@@ -270,6 +270,10 @@  go_langhook_post_options (const char **p
   if (flag_excess_precision_cmdline == EXCESS_PRECISION_DEFAULT)
     flag_excess_precision_cmdline = EXCESS_PRECISION_STANDARD;
 
+  /* Tail call optimizations can confuse uses of runtime.Callers.  */
+  if (!global_options_set.x_flag_optimize_sibling_calls)
+    global_options.x_flag_optimize_sibling_calls = 0;
+
   /* Returning false means that the backend should be used.  */
   return false;
 }