On Mon, 8 Apr 2013, Jakub Jelinek wrote:
> Hi!
>
> lhs ={v} {CLOBBER};
> stmts right now allow only VAR_DECL or MEM_REF lhs, but the forwprop code
> below on the attached testcase attempts to propagate an ARRAY_REF (of
> MEM_REF) into it. Fixed by not propagating in that case, allowing arbitrary
> memory lhs is IMHO unnecessary and such lhs's wouldn't be very useful for
> DSE anyway.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2013-04-08 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/56854
> * tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Don't
> forward into clobber stmts if it would change MEM_REF lhs into
> non-MEM_REF.
>
> * g++.dg/torture/pr56854.C: New test.
>
> --- gcc/tree-ssa-forwprop.c.jj 2013-02-25 23:51:21.000000000 +0100
> +++ gcc/tree-ssa-forwprop.c 2013-04-08 16:12:37.000000000 +0200
> @@ -826,7 +826,11 @@ forward_propagate_addr_expr_1 (tree name
> && integer_zerop (TREE_OPERAND (lhs, 1))
> && useless_type_conversion_p
> (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
> - TREE_TYPE (gimple_assign_rhs1 (use_stmt))))
> + TREE_TYPE (gimple_assign_rhs1 (use_stmt)))
> + /* Don't forward anything into clobber stmts if it would result
> + in the lhs no longer being a MEM_REF. */
> + && (!gimple_clobber_p (use_stmt)
> + || TREE_CODE (TREE_OPERAND (def_rhs, 0)) == MEM_REF))
> {
> tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
> tree new_offset, new_base, saved, new_lhs;
> --- gcc/testsuite/g++.dg/torture/pr56854.C.jj 2013-04-08 18:03:37.978009666
> +0200
> +++ gcc/testsuite/g++.dg/torture/pr56854.C 2013-04-08 18:03:09.000000000
> +0200
> @@ -0,0 +1,24 @@
> +// PR tree-optimization/56854
> +// { dg-do compile }
> +
> +inline void *
> +operator new (__SIZE_TYPE__, void *p) throw ()
> +{
> + return p;
> +}
> +
> +struct A
> +{
> + int a;
> + A () : a (0) {}
> + ~A () {}
> + A &operator= (const A &v) { this->~A (); new (this) A (v); return *this; }
> +};
> +A b[4], c[4];
> +
> +void
> +foo ()
> +{
> + for (int i = 0; i < 4; ++i)
> + c[i] = b[i];
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend
