[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 --- Comment #6 from CVS Commits --- The trunk branch has been updated by Andrew Pinski : https://gcc.gnu.org/g:7518e4c2f0758daac5d650d400565cf49ac3c8c5 commit r12-4661-g7518e4c2f0758daac5d650d400565cf49ac3c8c5 Author: Andrew Pinski Date: Sat Oct 23 19:24:43 2021 + Fix PR 102908: wrongly removing null pointer loads Just like PR 100382, here we have a DCE removing a null pointer load which is needed still. In this case, execute_fixup_cfg removes a store (correctly) and then removes the null load (incorrectly) due to not checking stmt_unremovable_because_of_non_call_eh_p. This patch adds the check in the similar way as the patch to fix PR 100382 did. gcc/ChangeLog: * tree-ssa-dce.c (simple_dce_from_worklist): Check stmt_unremovable_because_of_non_call_eh_p also before removing the statement.
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 Jakub Jelinek changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #5 from Jakub Jelinek --- Fixed.
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 --- Comment #4 from CVS Commits --- The master branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:80bbb7ff83d81544b09820428bdd7db9f50fe362 commit r12-378-g80bbb7ff83d81544b09820428bdd7db9f50fe362 Author: Jakub Jelinek Date: Mon May 3 12:03:02 2021 +0200 tree-ssa-dse: Fix up go.test/test/fixedbugs/issue16095.go miscompilation [PR100382] The new DCE code inside of tree DSE removes in -fnon-call-exceptions go code a load from NULL pointer the testcase relies on throwing an exception and so the test hangs. The following patch just repeats a check that e.g. tree-ssa-dce.c uses to prevent this. 2021-05-03 Jakub Jelinek PR tree-optimization/100382 * tree-ssa-dse.c: Include tree-eh.h. (dse_dom_walker::before_dom_children): Don't remove stmts if stmt_unremovable_because_of_non_call_eh_p is true.
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 --- Comment #3 from Richard Biener --- With the following patch this "issue" would show. Not sure why we think a postdom walk is appropriate for DSE rather than a reverse program order one. diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index aecf6ab8c46..5bb5adf43c6 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -39,6 +39,7 @@ along with GCC; see the file COPYING3. If not see #include "builtins.h" #include "gimple-fold.h" #include "gimplify.h" +#include "cfganal.h" /* This file implements dead store elimination. @@ -1280,7 +1281,16 @@ pass_dse::execute (function *fun) /* Dead store elimination is fundamentally a walk of the post-dominator tree and a backwards walk of statements within each block. */ dse_dom_walker walker (CDI_POST_DOMINATORS); - walker.walk (fun->cfg->x_exit_block_ptr); + //walker.walk (fun->cfg->x_exit_block_ptr); + int *rpo = XNEWVEC (int, n_basic_blocks_for_fn (fun) - NUM_FIXED_BLOCKS); + auto_bitmap exits; + edge entry = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (fun)); + bitmap_set_bit (exits, EXIT_BLOCK); + int n = rev_post_order_and_mark_dfs_back_seme +(fun, entry, exits, true, rpo, NULL); + for (int i = n; i != 0; --i) +walker.before_dom_children (BASIC_BLOCK_FOR_FN (fun, rpo[i-1])); + free (rpo); free_dominance_info (CDI_POST_DOMINATORS); unsigned todo = walker.todo ();
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382
--- Comment #2 from Richard Biener ---
Hum. OK, so DSE would also miss is_ctrl_altering_stmt (DCE checks this which
covers stmt_can_throw_internal). So with non-call-EH we even want to preserve
externally throwing EH? Given there's can_delete_dead_exceptions I wonder
if this applies to call EH as well. Note for this to make a practical
difference the throwing function would need to be pure at least (thus subject
to DCE in the first place).
So - wouldn't a more consistent check be
(!stmt_could_throw_p ()
|| cfun->can_delete_dead_exceptions)
?
int x, y;
int __attribute__((pure,noinline)) foo () { if (x) throw; return y; }
int main()
{
int a[2];
x = 1;
try {
int res = foo ();
a[0] = res;
} catch (...) {
return 0;
}
return 1;
}
should show this but the post-dom domwalk is plagued by the same ordering
issue as the dom domwalk was (we visit dom children in non-"RPO" order,
in this case inverted postorder).
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 Jakub Jelinek changed: What|Removed |Added Status|UNCONFIRMED |ASSIGNED Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org Ever confirmed|0 |1 Last reconfirmed||2021-05-02 --- Comment #1 from Jakub Jelinek --- Created attachment 50736 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50736=edit gcc12-pr100382.patch So perhaps this untested fix?
[Bug tree-optimization/100382] [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382 Jakub Jelinek changed: What|Removed |Added CC||ian at gcc dot gnu.org, ||rguenth at gcc dot gnu.org Target Milestone|--- |12.0
