https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81611
--- Comment #21 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- Author: aoliva Date: Tue Jan 30 17:40:50 2018 New Revision: 257194 URL: https://gcc.gnu.org/viewcvs?rev=257194&root=gcc&view=rev Log: [PR81611] accept copies in simple_iv_increment_p If there are copies between the GIMPLE_PHI at the loop body and the increment that reaches it (presumably through a back edge), still regard it as a simple_iv_increment, so that we won't consider the value in the back edge eligible for forwprop. Doing so would risk making the phi node and the incremented conflicting value live within the loop, and the phi node to be preserved for propagated uses after the loop. for gcc/ChangeLog PR tree-optimization/81611 * tree-ssa-dom.c (simple_iv_increment_p): Skip intervening copies. Modified: trunk/gcc/ChangeLog trunk/gcc/tree-ssa-dom.c
