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[Bug tree-optimization/58817] optimize alloca with constant size
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 21 Oct 2013 06:54:14 +0000
- Subject: [Bug tree-optimization/58817] optimize alloca with constant size
- Auto-submitted: auto-generated
- References: <bug-58817-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58817
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Transforming VLAs that way isn't a good idea, at least if the size isn't really
small, at least when the VLA isn't in a scope that dies at the function's end
(or if there is a chance the function might be inlined because of that
optimization). Because, unlike normal alloca, VLAs are deallocated already
when leading the scope they were declared in, and tons of programs rely on that
deallocation, otherwise you might have too big stack requirements.