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From: Richard Biener <rguenth@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-1939] tree-optimization/110298 - CFG cleanup and stale nb_iterations Date: Mon, 19 Jun 2023 11:02:39 +0000 (GMT) [thread overview] Message-ID: <20230619110239.015843858D28@sourceware.org> (raw) https://gcc.gnu.org/g:916add3bf6e46467e4391e358b11ecfbc4daa275 commit r14-1939-g916add3bf6e46467e4391e358b11ecfbc4daa275 Author: Richard Biener <rguenther@suse.de> Date: Mon Jun 19 09:52:45 2023 +0200 tree-optimization/110298 - CFG cleanup and stale nb_iterations When unrolling we eventually kill nb_iterations info since it may refer to removed SSA names. But we do this only after cleaning up the CFG which in turn can end up accessing it. Fixed by swapping the two. PR tree-optimization/110298 * tree-ssa-loop-ivcanon.cc (tree_unroll_loops_completely): Clear number of iterations info before cleaning up the CFG. * gcc.dg/torture/pr110298.c: New testcase. Diff: --- gcc/testsuite/gcc.dg/torture/pr110298.c | 20 ++++++++++++++++++++ gcc/tree-ssa-loop-ivcanon.cc | 7 ++++--- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/gcc/testsuite/gcc.dg/torture/pr110298.c b/gcc/testsuite/gcc.dg/torture/pr110298.c new file mode 100644 index 00000000000..139f5c77d89 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr110298.c @@ -0,0 +1,20 @@ +/* { dg-do compile } */ + +int a, b, c, d, e; +int f() { + c = 0; + for (; c >= 0; c--) { + d = 0; + for (; d <= 0; d++) { + e = 0; + for (; d + c + e >= 0; e--) + ; + a = 1; + b = 0; + for (; a; ++b) + a *= 2; + for (; b + d >= 0;) + return 0; + } + } +} diff --git a/gcc/tree-ssa-loop-ivcanon.cc b/gcc/tree-ssa-loop-ivcanon.cc index 6a962a9f503..491b57ec0f1 100644 --- a/gcc/tree-ssa-loop-ivcanon.cc +++ b/gcc/tree-ssa-loop-ivcanon.cc @@ -1520,15 +1520,16 @@ tree_unroll_loops_completely (bool may_increase_size, bool unroll_outer) } BITMAP_FREE (fathers); + /* Clean up the information about numbers of iterations, since + complete unrolling might have invalidated it. */ + scev_reset (); + /* This will take care of removing completely unrolled loops from the loop structures so we can continue unrolling now innermost loops. */ if (cleanup_tree_cfg ()) update_ssa (TODO_update_ssa_only_virtuals); - /* Clean up the information about numbers of iterations, since - complete unrolling might have invalidated it. */ - scev_reset (); if (flag_checking && loops_state_satisfies_p (LOOP_CLOSED_SSA)) verify_loop_closed_ssa (true); }
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