Re: [vta,vta4.4,trunk,4.4] fix -O0 -g vs -g0 codegen regression

[Alexandre Oliva <aoliva at redhat dot com>]

On May 27, 2009, Richard Guenther <richard.guenther@gmail.com> wrote:

> On Wed, May 27, 2009 at 6:39 PM, Alexandre Oliva <aoliva@redhat.com> wrote:
>> On May 27, 2009, Richard Guenther <richard.guenther@gmail.com> wrote:
>> 
>>> @@ -640,6 +633,9 @@ remove_unused_locals (void)
>>> Â Âvar_ann_t ann;
>>> Â Âbitmap global_unused_vars = NULL;
>> 
>>> + Âif (!optimize)
>>> + Â Âreturn;
>>> +
>> 
>>> This deserves a comment. ÂAlso checks for optimize later in that
>>> function should be removed.
>> 
>> *nod*
>> 
>>> Ok with that change (the other patch as well).
>> 
>> Thanks

In addition to the tree-inline.c patch posted before, here's the patch
I'm installing in trunk and 4.4, combining the two patches for
tree-ssa-live.c (the second reverted the first) with the suggestions
above.  Tested on x86_64-linux-gnu and i686-pc-linux-gnu.

for  gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	* tree-ssa-live.c (remove_unused_locals): Skip when not optimizing.
	Simplify other tests involving optimize.

Index: gcc/tree-ssa-live.c
===================================================================
--- gcc/tree-ssa-live.c.orig	2009-05-28 03:29:10.000000000 -0300
+++ gcc/tree-ssa-live.c	2009-05-28 03:44:46.000000000 -0300
@@ -639,6 +639,12 @@ remove_unused_locals (void)
   var_ann_t ann;
   bitmap global_unused_vars = NULL;
 
+  /* Removing declarations from lexical blocks when not optimizing is
+     not only a waste of time, it actually causes differences in stack
+     layout.  */
+  if (!optimize)
+    return;
+
   mark_scope_block_unused (DECL_INITIAL (current_function_decl));
 
   /* Assume all locals are unused.  */
@@ -701,8 +707,7 @@ remove_unused_locals (void)
 
       if (TREE_CODE (var) != FUNCTION_DECL
 	  && (!(ann = var_ann (var))
-	      || !ann->used)
-	  && (optimize || DECL_ARTIFICIAL (var)))
+	      || !ann->used))
 	{
 	  if (is_global_var (var))
 	    {
@@ -761,8 +766,7 @@ remove_unused_locals (void)
 	&& TREE_CODE (t) != PARM_DECL
 	&& TREE_CODE (t) != RESULT_DECL
 	&& !(ann = var_ann (t))->used
-	&& !TREE_ADDRESSABLE (t)
-	&& (optimize || DECL_ARTIFICIAL (t)))
+	&& !TREE_ADDRESSABLE (t))
       remove_referenced_var (t);
   remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
   if (dump_file && (dump_flags & TDF_DETAILS))


-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer