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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107274] Incorrect -Wuninitialized on indexed initialization Date: Mon, 17 Oct 2022 08:00:44 +0000 [thread overview] Message-ID: <bug-107274-4-s5W4zJBgFA@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107274-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107274 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Blocks| |24639 Resolution|--- |INVALID Status|UNCONFIRMED |RESOLVED --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- No, the issue is that you are accessing 8 bytes on the read and thus the padding you access that way is not initialized. Use *(unsigned int)b and the diagnostic goes away. [internally GCC doesn't consider an indirect load of size 8 ever aliasing a store to a 4 byte object - otherwise we wouldn't diagnose a partial uninit value -- like void example(unsigned long val) { char b[8]; b[0] = val; b[1] = val >> 8; b[2] = val >> 16; b[3] = val >> 24; val = *(unsigned long *)b; } which isn't diagnosed] Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639 [Bug 24639] [meta-bug] bug to track all Wuninitialized issues
prev parent reply other threads:[~2022-10-17 8:00 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-10-15 22:15 [Bug tree-optimization/107274] New: " keegan at undefinedbehaviour dot org 2022-10-15 22:19 ` [Bug tree-optimization/107274] " pinskia at gcc dot gnu.org 2022-10-17 8:00 ` rguenth at gcc dot gnu.org [this message]
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