https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112402
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>: https://gcc.gnu.org/g:b2b20b277988ab9ddb6ea82141075147b7b98f74 commit r15-3436-gb2b20b277988ab9ddb6ea82141075147b7b98f74 Author: Andrew Pinski <quic_apin...@quicinc.com> Date: Mon Sep 2 21:34:53 2024 -0700 split-path: Improve ifcvt heurstic for split path [PR112402] This simplifies the heurstic for split path to see if the join bb is a ifcvt candidate. For the predecessors bbs need either to be empty or only have one statement in them which could be a decent ifcvt candidate. The previous heurstics would miss that: ``` if (a) goto B else goto C; B: goto C; C: c = PHI<d,e> ``` Would be a decent ifcvt candidate. And would also miss: ``` if (a) goto B else goto C; B: d = f + 1; goto C; C: c = PHI<d,e> ``` Also since currently the max number of cmovs being able to produced is 3, we should only assume `<= 3` phis can be ifcvt candidates. The testcase changes for split-path-6.c is that lookharder function is a true ifcvt case where we would get cmov as expected; it looks like it was not a candidate when the heurstic was added but became one later on. pr88797.C is now rejected via it being an ifcvt candidate rather than being about DCE/const prop. The rest of the testsuite changes are just slight change in the dump, removing the "*diamnond" part as it was removed from the print. Bootstrapped and tested on x86_64. PR tree-optimization/112402 gcc/ChangeLog: * gimple-ssa-split-paths.cc (poor_ifcvt_pred): New function. (is_feasible_trace): Remove old heurstics for ifcvt cases. For num_stmts <=1 for both pred check poor_ifcvt_pred on both pred. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/split-path-11.c: Update scan. * gcc.dg/tree-ssa/split-path-2.c: Update scan. * gcc.dg/tree-ssa/split-path-5.c: Update scan. * gcc.dg/tree-ssa/split-path-6.c: Update scan. * g++.dg/tree-ssa/pr88797.C: Update scan. * gcc.dg/tree-ssa/split-path-13.c: New test. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
