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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/42512] [4.5 Regression] integer wrong code bug with loop Date: Tue, 25 Oct 2022 11:40:28 +0000 [thread overview] Message-ID: <bug-42512-4-VKHt7bRwQs@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-42512-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42512 --- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>: https://gcc.gnu.org/g:4c5b1160776382772fc0a33130dfaf621699fdbf commit r13-3486-g4c5b1160776382772fc0a33130dfaf621699fdbf Author: Richard Biener <rguenther@suse.de> Date: Mon Oct 24 08:52:12 2022 +0200 tree-optimization/107176 - SCEV analysis association issue The following fixes a wrong-code issue caused by SCEV analysis associating an addition due trying to use tail-recursion in follow_ssa_edge_expr. That causes us to apply a conversion at the wrong point and thus miscompute the scalar evolution of an induction variable. This reverts the PR66375 fix and revisits the PR42512 fix by keeping the evolution symbolic up to the point we process the first linear function when we then can check for the supported cases and substitute the whole symbolic expression with the built chrec substituting the proper initial value. To simplify passing around things and to clarify scoping of the involved functions this change wraps the SCEV DFS walking code into a class. PR tree-optimization/107176 PR tree-optimization/66375 PR tree-optimization/42512 * tree-scalar-evolution.cc (follow_ssa_edge_expr): Revert the PR66375 fix, do not not associate PLUS_EXPR to be able to use tail-recursion. (follow_ssa_edge_binary): Likewise. (interpret_loop_phi): Revert PR42512 fix, do not throw away analyze_evolution_in_loop result after the fact. (follow_ssa_edge_expr): When reaching halting_phi initalize the evolution to the symbolic value of the PHI result. (add_to_evolution_1): When adding the first evolution verify we can handle the expression wrapping the symbolic evolution and replace that in full using the initial condition. (class scev_dfs): New, contains ... (follow_ssa_edge_expr, follow_ssa_edge_binary, follow_ssa_edge_in_condition_phi_branch, follow_ssa_edge_in_condition_phi, follow_ssa_edge_inner_loop_phi, add_to_evolution, add_to_evolution_1): ... these with loop and halting_phi arguments in class data. (scev_dfs::get_ev): New toplevel DFS entry, start with a chrec_dont_know evolution. (analyze_evolution_in_loop): Use scev_dfs. * gcc.dg/torture/pr107176.c: New testcase.
next parent reply other threads:[~2022-10-25 11:40 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-42512-4@http.gcc.gnu.org/bugzilla/> 2022-10-25 11:40 ` cvs-commit at gcc dot gnu.org [this message] 2009-12-26 19:27 [Bug c/42512] New: possible integer wrong code bug regehr at cs dot utah dot edu 2009-12-26 20:00 ` [Bug middle-end/42512] [4.5 Regression] integer wrong code bug with loop jakub at gcc dot gnu dot org 2009-12-26 22:13 ` hjl dot tools at gmail dot com 2009-12-26 22:16 ` hjl dot tools at gmail dot com 2009-12-27 14:43 ` ebotcazou at gcc dot gnu dot org 2010-01-08 14:07 ` rguenth at gcc dot gnu dot org 2010-01-08 15:00 ` rguenth at gcc dot gnu dot org 2010-01-08 16:20 ` spop at gcc dot gnu dot org 2010-01-08 16:53 ` rguenth at gcc dot gnu dot org 2010-01-08 17:07 ` rguenth at gcc dot gnu dot org 2010-01-08 17:21 ` rguenth at gcc dot gnu dot org 2010-01-08 17:55 ` Sebastian Pop 2010-01-08 17:55 ` sebpop at gmail dot com 2010-01-09 12:04 ` rguenth at gcc dot gnu dot org 2010-01-09 12:04 ` rguenth at gcc dot gnu dot org 2010-02-07 4:49 ` hjl at gcc dot gnu dot org
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