[PATCH] Fix PR57287 (again)

[Richard Biener <rguenther at suse dot de>]

This makes sure we cleanup at least some of the spurious copies
that can be introduced for example by jump-threading and that confuse
uninitialized var analysis.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2013-08-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/57287
	* tree-ssa-copy.c (may_propagate_copy): Allow propagating
	of default defs that appear in abnormal PHI nodes.

	* gcc.dg/pr57287-2.c: New testcase.

Index: gcc/tree-ssa-copy.c
===================================================================
*** gcc/tree-ssa-copy.c	(revision 202068)
--- gcc/tree-ssa-copy.c	(working copy)
*************** may_propagate_copy (tree dest, tree orig
*** 60,66 ****
  
    /* If ORIG flows in from an abnormal edge, it cannot be propagated.  */
    if (TREE_CODE (orig) == SSA_NAME
!       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
      return false;
  
    /* If DEST is an SSA_NAME that flows from an abnormal edge, then it
--- 60,72 ----
  
    /* If ORIG flows in from an abnormal edge, it cannot be propagated.  */
    if (TREE_CODE (orig) == SSA_NAME
!       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig)
!       /* If it is the default definition and an automatic variable then
!          we can though and it is important that we do to avoid
! 	 uninitialized regular copies.  */
!       && !(SSA_NAME_IS_DEFAULT_DEF (orig)
! 	   && (SSA_NAME_VAR (orig) == NULL_TREE
! 	       || TREE_CODE (SSA_NAME_VAR (orig)) == VAR_DECL)))
      return false;
  
    /* If DEST is an SSA_NAME that flows from an abnormal edge, then it
Index: gcc/testsuite/gcc.dg/pr57287-2.c
===================================================================
*** gcc/testsuite/gcc.dg/pr57287-2.c	(revision 0)
--- gcc/testsuite/gcc.dg/pr57287-2.c	(working copy)
***************
*** 0 ****
--- 1,35 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -Wall" } */
+ 
+ #include <setjmp.h>
+ 
+ struct node
+ {
+   struct node *next;
+   char *name;
+ } *list;
+ 
+ struct node *list;
+ struct node *head (void);
+ 
+ sigjmp_buf *bar (void);
+ 
+ int baz (void)
+ {
+   struct node *n;
+   int varseen = 0;
+ 
+   list = head ();
+   for (n = list; n; n = n->next)
+     {
+       if (!varseen)
+ 	varseen = 1;
+ 
+       sigjmp_buf *buf = bar ();  /* { dg-bogus "may be used uninitialized" "" } */
+       __sigsetjmp (*buf, 1);
+     }
+ 
+   if (!varseen)
+     return 0;
+   return 1;
+ }