[Bug middle-end/98583] missing -Wuninitialized reading from a second VLA in its own block
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98583 Martin Sebor changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #4 from Martin Sebor --- Fixed in GCC 12.
[Bug middle-end/98583] missing -Wuninitialized reading from a second VLA in its own block
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98583 --- Comment #3 from CVS Commits --- The master branch has been updated by Martin Sebor : https://gcc.gnu.org/g:2efe245bb88bf4574e322ef7e6d2df83d9e13237 commit r12-783-g2efe245bb88bf4574e322ef7e6d2df83d9e13237 Author: Martin Sebor Date: Thu May 13 16:05:50 2021 -0600 Avoid -Wuninitialized false negatives with sanitization and VLAs. Resolves: PR tree-optimization/93100 - gcc -fsanitize=address inhibits -Wuninitialized PR middle-end/98583 - missing -Wuninitialized reading from a second VLA in its own block gcc/ChangeLog: PR tree-optimization/93100 PR middle-end/98583 * tree-ssa-uninit.c (check_defs): Exclude intrinsic functions that don't modify referenced objects. gcc/testsuite/ChangeLog: PR tree-optimization/93100 PR middle-end/98583 * g++.dg/warn/uninit-pr93100.C: New test. * gcc.dg/uninit-pr93100.c: New test. * gcc.dg/uninit-pr98583.c: New test.
[Bug middle-end/98583] missing -Wuninitialized reading from a second VLA in its own block
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98583 Martin Sebor changed: What|Removed |Added Keywords||patch Target Milestone|--- |12.0 Status|NEW |ASSIGNED Known to fail||10.3.0, 11.1.0, 12.0, 9.2.0 Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot gnu.org --- Comment #2 from Martin Sebor --- Patch: https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570117.html
[Bug middle-end/98583] missing -Wuninitialized reading from a second VLA in its own block
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98583 Richard Biener changed: What|Removed |Added Ever confirmed|0 |1 Last reconfirmed||2021-01-08 Status|UNCONFIRMED |NEW --- Comment #1 from Richard Biener --- The issue is that __builtin_stack_restore is considered a possible definition by the alias machinery (it needs to be treated as barrier for code motion). check_defs can probably skip __builtin_stack_restore unconditionally (alternatively the uninit pass can stop walking at allocation sites but it's run too early to not need its own tracking of which allocation an object belongs to). diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c index 0800f596ab1..33a32eaaa37 100644 --- a/gcc/tree-ssa-uninit.c +++ b/gcc/tree-ssa-uninit.c @@ -216,6 +216,9 @@ check_defs (ao_ref *ref, tree vdef, void *data_) return true; return false; } + /* End of VLA scope is not a kill. */ + if (gimple_call_builtin_p (def_stmt, BUILT_IN_STACK_RESTORE)) +return false; /* Found a may-def on this path. */ data->found_may_defs = true; return true; fixes this bug (pre-approved if it tests OK).
