On Wed, Feb 10, 2016 at 1:27 PM, Richard Biener <richard.guent...@gmail.com> wrote: > > On Wed, Feb 10, 2016 at 12:34 PM, Bin Cheng <bin.ch...@arm.com> wrote: > > Hi, > > This is another way to fix PR68021, and I think it's the least intrusive > > way. The issue is triggered in a special case in which cand is a original > > biv, and use denotes the value of the biv itself. In this case, the use is > > added specifically for the original biv, as a result, get_computation_aff > > isn't called for the <cand, use> pair before rewriting the use. It is > > possible that constant_multiple_of/operand_equal_q could fail because of > > inconsistent fold behavior. The fold behavior is fully described in > > PR68021. > > This patch fixes IVOPT part of issue by setting ratio to 1, because it is > > known that the use has the value of the biv cand. > > > > Bootstrap and test on x86_64 and aarch64. Is it OK if no failures? > > Ok, but please add a comment why we have this special-casing instead > of relying on constant_multiple_of. Done, patch applied at revision 233269.
Thanks, bin > > > Thanks, > Richard. > > > Thanks, > > bin > > > > 2016-02-09 Bin Cheng <bin.ch...@arm.com> > > > > PR tree-optimization/68021 > > * tree-ssa-loop-ivopts.c (get_computation_aff): Set ratio to 1 if > > when computing the value of biv cand by itself. > > > > gcc/testsuite/ChangeLog > > 2016-02-09 Bin Cheng <bin.ch...@arm.com> > > > > PR tree-optimization/68021 > > * gcc.dg/tree-ssa/pr68021.c: New test.
