On Wed, Apr 27, 2016 at 5:49 PM, Bin Cheng <bin.ch...@arm.com> wrote: > Hi, > Currently tree if-conversion only supports PHIs with no more than two > arguments unless the loop is marked with "simd pragma". This patch makes > such PHIs supported unconditionally if they have no more than MAX_PHI_ARG_NUM > arguments, thus cases like PR56541 can be fixed. Note because a chain of > "?:" operators are needed to compute mult-arg PHI, this patch records the > case and versions loop so that vectorizer can fall back to the original loop > if if-conversion+vectorization isn't beneficial. Ideally, cost computation > in vectorizer should be improved to measure benefit against the original > loop, rather than if-converted loop. So far MAX_PHI_ARG_NUM is set to (4) > because cases with more arguments are rare and not likely beneficial. > > Apart from above change, the patch also makes changes like: only split > critical edge when we have to; cleanups code logic in if_convertible_loop_p > about aggressive_if_conv. > > Bootstrap and test on x86_64 and AArch64, is it OK?
Can you make this magic number a --param please? Otherwise ok. Thanks, Richard. > Thanks, > bin > > 2016-04-26 Bin Cheng <bin.ch...@arm.com> > > PR tree-optimization/56541 > * tree-if-conv.c (MAX_PHI_ARG_NUM): New macro. > (any_complicated_phi): New static variable. > (aggressive_if_conv): Delete. > (if_convertible_phi_p): Support PHIs with more than two arguments. > (if_convertible_bb_p): Remvoe check on aggressive_if_conv and > critical pred edges. > (ifcvt_split_critical_edges): Support PHIs with more than two > arguments by checking new parameter. Only split critical edges > if needed. > (tree_if_conversion): Handle simd pragma marked loop using new > local variable aggressive_if_conv. Check any_complicated_phi. > > gcc/testsuite/ChangeLog > 2016-04-26 Bin Cheng <bin.ch...@arm.com> > > PR tree-optimization/56541 > * gcc.dg/tree-ssa/ifc-pr56541.c: New test.
