[Bug tree-optimization/71026] Missing division optimizations

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71026

--- Comment #9 from Wilco <wilco at gcc dot gnu.org> ---
Author: wilco
Date: Thu Nov 16 11:54:49 2017
New Revision: 254816

URL: https://gcc.gnu.org/viewcvs?rev=254816&root=gcc&view=rev
Log:
Canonicalize constant multiplies in division

This patch implements some of the optimizations discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71026.

Canonicalize x / (C1 * y) into (x * C2) / y.

This moves constant multiplies out of the RHS of a division in order
to allow further simplifications (such as (C1 * x) / (C2 * y) ->
(C3 * x) / y) and to enable more reciprocal CSEs.

2017-11-16  Wilco Dijkstra  <wdijkstr@arm.com>
            Jackson Woodruff  <jackson.woodruff@arm.com>

    gcc/
        PR tree-optimization/71026
        * match.pd: Canonicalize constant multiplies in division.

    gcc/testsuite/
        PR tree-optimization/71026
        * gcc.dg/cse_recip.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/cse_recip.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/match.pd
    trunk/gcc/testsuite/ChangeLog