On Thu, 7 Mar 2013, Jakub Jelinek wrote:
> Hi!
>
> During zero_one_operation I believe we can count in the chain having single
> uses if we go through rhs1s, but the change from last year also added
> looking through rhs2, and there I don't see anything that would guarantee
> a single use, and the following testcase shows where it has two uses.
>
> If it has more than one use, obviously we can't change the pow call just
> because in one of the uses we'd like to remove one multiplication.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2013-03-07 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/56559
> * tree-ssa-reassoc.c (zero_one_operation): When looking at rhs2,
> check that it has only a single use.
>
> * gcc.dg/tree-ssa/reassoc-26.c: New test.
>
> --- gcc/tree-ssa-reassoc.c.jj 2013-02-18 16:39:55.000000000 +0100
> +++ gcc/tree-ssa-reassoc.c 2013-03-07 10:09:22.048925800 +0100
> @@ -1107,7 +1107,8 @@ zero_one_operation (tree *def, enum tree
> the operand might be hiding in the rightmost one. */
> if (opcode == MULT_EXPR
> && gimple_assign_rhs_code (stmt) == opcode
> - && TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME)
> + && TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
> + && has_single_use (gimple_assign_rhs2 (stmt)))
> {
> gimple stmt2 = SSA_NAME_DEF_STMT (gimple_assign_rhs2 (stmt));
> if (stmt_is_power_of_op (stmt2, op))
> --- gcc/testsuite/gcc.dg/tree-ssa/reassoc-26.c.jj 2013-03-07
> 10:10:49.400749110 +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/reassoc-26.c 2013-03-07
> 10:10:18.000000000 +0100
> @@ -0,0 +1,12 @@
> +/* PR tree-optimization/56559 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -ffast-math" } */
> +
> +double a, b, c, d, e;
> +
> +void
> +foo ()
> +{
> + a = e * e;
> + b = d * e + c * e * a;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
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