On 09/13/2017 03:22 AM, Jackson Woodruff wrote: > On 09/12/2017 11:43 PM, Jeff Law wrote: >> On 09/06/2017 03:54 AM, Jackson Woodruff wrote: >>> Hi all, >>> >>> This patch is split from part (1/2). It includes the patterns that have >>> been moved out of fold-const.c >>> >>> >>> It also removes an (almost entirely) redundant pattern: >>> >>> (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2) >>> >>> which was only used in special cases, either with combinations >>> of flags like -fno-reciprocal-math -funsafe-math-optimizations >>> and cases where C was sNaN, or small enough to result in infinity. >>> >>> This pattern is covered by: >>> >>> (A / C1) +- (A / C2) -> (with O1 and reciprocal math) >>> A * (1 / C1) +- A * (1 / C2) -> >>> A * (1 / C1 +- 1 / C2) >>> >>> The previous pattern required funsafe-math-optimizations. >>> >>> To adjust for this case, the testcase has been updated to require O1 so >>> that the optimization is still performed. >>> >>> >>> This pattern is moved verbatim into match.pd: >>> >>> (A / C) +- (B / C) -> (A +- B) / C. >>> >>> OK for trunk? >>> >>> Jackson >>> >>> gcc/ >>> >>> 2017-08-30 Jackson Woodruff <jackson.woodr...@arm.com> >>> >>> PR 71026/tree-optimization >>> * match.pd: Move RDIV patterns from fold-const.c >>> * fold-const.c (distribute_real_division): Removed. >>> (fold_binary_loc): Remove calls to distribute_real_divison. >>> >>> gcc/testsuite/ >>> >>> 2017-08-30 Jackson Woodruff <jackson.woodr...@arm.com> >>> >>> PR 71026/tree-optimization >>> * gcc/testsuire/gcc.dg/fold-div-1.c: Use O1. >> >> Didn't you lose the case where the operator is MULT_EXPR rather than >> RDIV_EXPR? >> >> If I'm reading things correctly, arg0 and arg1 could be a RDIV_EXPR or a >> MULT_EXPR and we distribute both cases (as long as they are both the >> same code). > >> Your match.pd pattern only handle rdiv. >> > > In the fold_plusminus_mult_expr function in fold-const.c, we still do > the simplification: > > (A * C) +- (B * C) -> (A+-B) * C > > So the pattern I introduced only needs to handle the division case. OK. I was hoping that we had code elsewhere to handle the MULT case.
> >> Now it may be the case that MULT_EXPR doesn't happen anymore in practice >> -- the code in fold-const is quote old and much of it was written before >> we regularly added tests for optimization and canonicalization. So I'm >> not surprised nothing in this testsuite trips over this omission. > > In gcc.dg/fold-plusmult.c, we test whether 2*a + 2*a is folded into a * > 4, which comes close. > > There are also a few tests for this in gcc.dg/tree-ssa/pr23294.c, > although again, they are use constants for A and B. Great. Thanks for verifying we've got at least some minimal coverage. Do you have commit privs? I'm going to give the patch a final looksie shortly. jeff
