On Mon, 2013-02-18 at 13:05 +0100, Richard Biener wrote:
> On Fri, Feb 15, 2013 at 6:53 PM, Bill Schmidt
> <wschm...@linux.vnet.ibm.com> wrote:
> > When we remove __builtin_pow statements as part of reassociation, we
> > have to unlink the associated VDEF. We've always done this when we
> > directly remove the statement. However, in reassociation the statements
> > are sometimes modified in place instead of removed, potentially leaving
> > one or more dangling VUSEs. This patch solves the problem by unlinking
> > the VDEF when the statement's operands are added to the ops list.
> >
> > Bootstrapped and regression tested on powerpc64-unknown-linux-gnu with
> > no new regressions. The new test case is the code that exposed the
> > problem in PR56321. Ok for trunk?
>
> No, that's way to complicated. The issue is that
>
> static void
> propagate_op_to_single_use (tree op, gimple stmt, tree *def)
> {
> ...
> gsi = gsi_for_stmt (stmt);
> gsi_remove (&gsi, true);
> release_defs (stmt);
>
> if (is_gimple_call (stmt))
> unlink_stmt_vdef (stmt);
>
> tries to unlink the stmts VDEF after releasing it. That doesn't work.
>
> A proper fix is
>
> Index: tree-ssa-reassoc.c
> ===================================================================
> --- tree-ssa-reassoc.c (revision 196115)
> +++ tree-ssa-reassoc.c (working copy)
> @@ -1062,11 +1062,9 @@ propagate_op_to_single_use (tree op, gim
> if (TREE_CODE (op) != SSA_NAME)
> update_stmt (use_stmt);
> gsi = gsi_for_stmt (stmt);
> + unlink_stmt_vdef (stmt);
> gsi_remove (&gsi, true);
> release_defs (stmt);
> -
> - if (is_gimple_call (stmt))
> - unlink_stmt_vdef (stmt);
> }
>
> /* Walks the linear chain with result *DEF searching for an operation
>
> I'll take care of it in a second.
OK, thanks! Appreciate it.
Bill
>
> Thanks,
> Richard.
>
>
> > Thanks,
> > Bill
> >
> >
> > Index: gcc/testsuite/gcc.dg/tree-ssa/pr56321.c
> > ===================================================================
> > --- gcc/testsuite/gcc.dg/tree-ssa/pr56321.c (revision 0)
> > +++ gcc/testsuite/gcc.dg/tree-ssa/pr56321.c (revision 0)
> > @@ -0,0 +1,12 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> > +
> > +float foo(int n)
> > +{
> > + return ((2.0*n*n)/3.0+2.0*n);
> > +}
> > +
> > +/* { dg-final { scan-tree-dump-times "__builtin_pow" 0 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times " \\* " 2 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times " \\+ " 1 "optimized" } } */
> > +/* { dg-final { cleanup-tree-dump "optimized" } } */
> > Index: gcc/tree-ssa-reassoc.c
> > ===================================================================
> > --- gcc/tree-ssa-reassoc.c (revision 196053)
> > +++ gcc/tree-ssa-reassoc.c (working copy)
> > @@ -3386,6 +3386,10 @@ linearize_expr_tree (vec<operand_entry_t> *ops, gi
> > {
> > add_repeat_to_ops_vec (ops, base, exponent);
> > gimple_set_visited (binrhsdef, true);
> > + // We may not physically remove the call later because
> > + // stmts are preferably modified in place. But we have
> > + // to remove any VDEF associated with the call regardless.
> > + unlink_stmt_vdef (binrhsdef);
> > }
> > else
> > add_to_ops_vec (ops, binrhs);
> > @@ -3396,6 +3400,10 @@ linearize_expr_tree (vec<operand_entry_t> *ops, gi
> > {
> > add_repeat_to_ops_vec (ops, base, exponent);
> > gimple_set_visited (binlhsdef, true);
> > + // We may not physically remove the call later because
> > + // stmts are preferably modified in place. But we have
> > + // to remove any VDEF associated with the call regardless.
> > + unlink_stmt_vdef (binlhsdef);
> > }
> > else
> > add_to_ops_vec (ops, binlhs);
> > @@ -3445,6 +3453,10 @@ linearize_expr_tree (vec<operand_entry_t> *ops, gi
> > {
> > add_repeat_to_ops_vec (ops, base, exponent);
> > gimple_set_visited (SSA_NAME_DEF_STMT (binrhs), true);
> > + // We may not physically remove the call later because
> > + // stmts are preferably modified in place. But we have
> > + // to remove any VDEF associated with the call regardless.
> > + unlink_stmt_vdef (SSA_NAME_DEF_STMT (binrhs));
> > }
> > else
> > add_to_ops_vec (ops, binrhs);
> >
> >
>
