[PATCH][4.2] Fix PR31797, make forwprop not propagate into a stmt that has volatile ops

[Richard Guenther <rguenther at suse dot de>]

This fixes the mentioned PR where we end up with a mismatch between
the stmt annotation (has_volatile_ops) and the tree flags in the stmt
operands (it has TREE_THIS_VOLATILE and TREE_SIDE_EFFECTS set).

Fixed by not creating a stmt that update_stmt () will create this mismatch
for.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to the
4.2 branch and the trunk.

Richard.

2007-05-12  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/31797
	* tree-ssa-forwprop.c (forward_propagate_addr_expr): Do not
	propagate into a stmt that has volatile ops.

	* gcc.c-torture/compile/pr31797.c: New testcase.

Index: tree-ssa-forwprop.c
===================================================================
*** tree-ssa-forwprop.c	(revision 124635)
--- tree-ssa-forwprop.c	(working copy)
*************** forward_propagate_addr_expr (tree stmt, 
*** 843,857 ****
  	  continue;
  	}
  
!      /* If the use is in a deeper loop nest, then we do not want
! 	to propagate the ADDR_EXPR into the loop as that is likely
! 	adding expression evaluations into the loop.  */
        if (bb_for_stmt (use_stmt)->loop_depth > stmt_loop_depth)
  	{
  	  all = false;
  	  continue;
  	}
!       
        result = forward_propagate_addr_expr_1 (stmt, use_stmt, some);
        *some |= result;
        all &= result;
--- 843,864 ----
  	  continue;
  	}
  
!       /* If the use is in a deeper loop nest, then we do not want
! 	 to propagate the ADDR_EXPR into the loop as that is likely
! 	 adding expression evaluations into the loop.  */
        if (bb_for_stmt (use_stmt)->loop_depth > stmt_loop_depth)
  	{
  	  all = false;
  	  continue;
  	}
! 
!       /* If the use_stmt has side-effects, don't propagate into it.  */
!       if (stmt_ann (use_stmt)->has_volatile_ops)
!         {
! 	  all = false;
! 	  continue;
! 	}
!  
        result = forward_propagate_addr_expr_1 (stmt, use_stmt, some);
        *some |= result;
        all &= result;
Index: testsuite/gcc.c-torture/compile/pr31797.c
===================================================================
*** testsuite/gcc.c-torture/compile/pr31797.c	(revision 0)
--- testsuite/gcc.c-torture/compile/pr31797.c	(revision 0)
***************
*** 0 ****
--- 1,31 ----
+ struct GTeth_desc
+ {
+   unsigned ed_cmdsts;
+ };
+ struct GTeth_softc
+ {
+   struct GTeth_desc txq_desc[32];
+   unsigned int txq_fi;
+   unsigned int txq_nactive;
+ };
+ 
+ void
+ GTeth_txq_free (struct GTeth_softc *sc)
+ {
+   struct GTeth_desc *txd = &sc->txq_desc[0];
+   txd->ed_cmdsts &= ~(1U << (31));
+ }
+ void
+ GTeth_txq_done (struct GTeth_softc *sc)
+ {
+   while (sc->txq_nactive > 0)
+     {
+       volatile struct GTeth_desc *txd = &sc->txq_desc[sc->txq_fi];
+       if (txd->ed_cmdsts)
+ 	{
+ 	  if (sc->txq_nactive == 1)
+ 	    return;
+ 	}
+       GTeth_txq_free (sc);
+     }
+ }