[Bug tree-optimization/16225] [3.5 regression] ICE: verify_ssa failed.

["zhangjie at magima dot com dot cn" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From zhangjie at magima dot com dot cn  2004-07-30 06:50 -------
I believe the bug is caused by a problem in alias analysis. At the end of
alias1, TMT.9 might alias x and bits:

    Variable: TMT.9, UID 13, is global, call clobbered, may aliases: { x bits }

and was call-clobbered. However, add_may_alias () failed to set x call-clobbered:

    Variable: x, UID 1, is an alias tag, default def: x_9

This inconsistency resulted in the bug. At the one hand, add_stmt_operand ()
added x as a V_MAY_DEF when renaming variables at the end of alias1 because x
wass an alias of TMT.9 and TMT.9 was call-clobbered. At the other hand, tailr1
pass failed to recognize that x was an alias of a call-clobbered variable. It
was executed.

This patch will make the call-clobbered information consistent and fix this bug.


2004-07-30  Jie Zhang  <zhangjie@magima.com.cn>

	PR tree-optimization/16225
	* tree-ssa-alias.c (add_may_alias): If 'alias' is call-clobbered, so
	are 'var' and its aliases.

*** tree-ssa-alias.c.old	2004-07-24 09:05:44.000000000 +0800
--- tree-ssa-alias.c	2004-07-30 13:13:06.000000000 +0800
*************** add_may_alias (tree var, tree alias)
*** 1678,1686 ****
    if (is_call_clobbered (var))
      mark_call_clobbered (alias);
  
!   /* Likewise.  If ALIAS is call-clobbered, so is VAR.  */
    else if (is_call_clobbered (alias))
!     mark_call_clobbered (var);
  
    VARRAY_PUSH_TREE (v_ann->may_aliases, alias);
    a_ann->is_alias_tag = 1;
--- 1678,1690 ----
    if (is_call_clobbered (var))
      mark_call_clobbered (alias);
  
!   /* Likewise.  If ALIAS is call-clobbered, so are VAR and its aliases.  */
    else if (is_call_clobbered (alias))
!     {
!       mark_call_clobbered (var);
!       for (i = 0; i < VARRAY_ACTIVE_SIZE (v_ann->may_aliases); i++)
!         mark_call_clobbered (VARRAY_TREE (v_ann->may_aliases, i));
!     }
  
    VARRAY_PUSH_TREE (v_ann->may_aliases, alias);
    a_ann->is_alias_tag = 1;


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16225