r257194 - in /trunk/gcc: ChangeLog tree-ssa-dom.c

[aoliva@gcc.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