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* [Bug tree-optimization/102155] New: LIM fill_always_executed_in handles contains_call incorrectly @ 2021-09-01 7:09 rguenth at gcc dot gnu.org 2021-09-01 7:58 ` [Bug tree-optimization/102155] " rguenth at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-09-01 7:09 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102155 Bug ID: 102155 Summary: LIM fill_always_executed_in handles contains_call incorrectly Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: rguenth at gcc dot gnu.org Target Milestone: --- fill_always_executed_in walks loop bodies in dominator order (get_loop_body_in_dom_order) but that does not run into BB3 before marking BB4 as always executed: do { BB1: if (x) BB2: if (y) BB3: bar(); BB4; } while (++i < n); the dominator children of BB1 are BB2 and BB4, BB3 with the call to bar() is only a dominator child of BB2. Since LIM gives up on "unanalyzable" refs like calls a testcase that is miscompiled is a bit difficult to construct - it requires a 'pure' (or const) call but whether it's valid for those to exit the program could be subject to discussion. The following uses a looping const function to show the effect and the testcase segfaults with -O1+ while it runs into the infinite loop at -O0. Note we'd technically need to set looping_const but there's now way to do this and with just -fno-inline and letting IPA figure out looping-const dominator children are ordered in a "lucky" way for fill_sons_in_loop to compute an order that happens to work. extern void abort (void); int flag[32]; int __attribute__((noinline,const)) bar (int i) { if (i) return i; while (1); } int __attribute__((noipa)) foo (int *p, int n) { int i = 0, res = 0; do { if (!flag[i]) { if (i % 3 == 0) res += bar (i); else res++; } res += *p; } while (++i < n); return res; } int main() { if (foo ((int *)0, 5) != 0) abort (); return 0; } ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102155] LIM fill_always_executed_in handles contains_call incorrectly 2021-09-01 7:09 [Bug tree-optimization/102155] New: LIM fill_always_executed_in handles contains_call incorrectly rguenth at gcc dot gnu.org @ 2021-09-01 7:58 ` rguenth at gcc dot gnu.org 2021-09-02 5:55 ` cvs-commit at gcc dot gnu.org 2021-09-02 7:56 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-09-01 7:58 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102155 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2021-09-01 Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Status|UNCONFIRMED |ASSIGNED Ever confirmed|0 |1 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102155] LIM fill_always_executed_in handles contains_call incorrectly 2021-09-01 7:09 [Bug tree-optimization/102155] New: LIM fill_always_executed_in handles contains_call incorrectly rguenth at gcc dot gnu.org 2021-09-01 7:58 ` [Bug tree-optimization/102155] " rguenth at gcc dot gnu.org @ 2021-09-02 5:55 ` cvs-commit at gcc dot gnu.org 2021-09-02 7:56 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2021-09-02 5:55 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102155 --- Comment #1 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:f482bf2af86990329b4df660f8c1eb9e094de9f9 commit r12-3307-gf482bf2af86990329b4df660f8c1eb9e094de9f9 Author: Richard Biener <rguenther@suse.de> Date: Wed Sep 1 09:51:45 2021 +0200 tree-optimization/102155 - fix LIM fill_always_executed_in CFG walk This fixes the CFG walk order of fill_always_executed_in to use RPO oder rather than the dominator based order computed by get_loop_body_in_dom_order. That fixes correctness issues with unordered dominator children. The RPO order computed by rev_post_order_and_mark_dfs_back_seme in its for-iteration mode is a good match for the algorithm. 2021-09-01 Richard Biener <rguenther@suse.de> PR tree-optimization/102155 * tree-ssa-loop-im.c (fill_always_executed_in_1): Iterate over a part of the RPO array and do not recurse here. Dump blocks marked as always executed. (fill_always_executed_in): Walk over the RPO array and process loops whose header we run into. (loop_invariant_motion_in_fun): Compute the first RPO using rev_post_order_and_mark_dfs_back_seme in iteration order and pass that to fill_always_executed_in. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102155] LIM fill_always_executed_in handles contains_call incorrectly 2021-09-01 7:09 [Bug tree-optimization/102155] New: LIM fill_always_executed_in handles contains_call incorrectly rguenth at gcc dot gnu.org 2021-09-01 7:58 ` [Bug tree-optimization/102155] " rguenth at gcc dot gnu.org 2021-09-02 5:55 ` cvs-commit at gcc dot gnu.org @ 2021-09-02 7:56 ` rguenth at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-09-02 7:56 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102155 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|ASSIGNED |RESOLVED --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- It seems I was mistaken, get_loop_body_in_dom_order seems to exactly care for this specific case. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-09-02 7:56 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-09-01 7:09 [Bug tree-optimization/102155] New: LIM fill_always_executed_in handles contains_call incorrectly rguenth at gcc dot gnu.org 2021-09-01 7:58 ` [Bug tree-optimization/102155] " rguenth at gcc dot gnu.org 2021-09-02 5:55 ` cvs-commit at gcc dot gnu.org 2021-09-02 7:56 ` rguenth at gcc dot gnu.org
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