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Re: PR65416, alloca on xtensa
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Max Filippov <jcmvbkbc at gmail dot com>
- Cc: Sterling Augustine <augustine dot sterling at gmail dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Marc Gauthier <marc at cadence dot com>
- Date: Fri, 13 Mar 2015 15:56:38 -0500
- Subject: Re: PR65416, alloca on xtensa
- Authentication-results: sourceware.org; auth=none
- References: <CAMo8BfKLG7oVXu0SSMe9j6P5TYPYEPRJwGJ=4VbHLMR38_QS2g at mail dot gmail dot com> <20150313201818 dot GE7174 at gate dot crashing dot org> <CAMo8BfJFB8LWXDRRbYVkOP+j=5iazxqzbkzb-Pnvz7iz8MB0Rg at mail dot gmail dot com>
On Fri, Mar 13, 2015 at 11:36:47PM +0300, Max Filippov wrote:
> >> 2. alloca seems to make an additional 16-bytes padding to each stack
> >> allocation: alloca(1) results in moving sp down by 32 bytes, alloca(17)
> >> moves it by 48 bytes, etc.
> > This sounds like PR 50938, 47353, 34548, maybe more? Happens on most
> > targets.
> Exactly! (And I was wrong about 1 byte, it needs at least 2 for 32
> bytes result).
Yeah, same bug :-)
> But...those PRs are marked as duplicates of a fixed PR 34548.
> Looks like it's not fixed or there's a regression?
It's not fixed. Removing the STACK_POINTER_OFFSET check from
allocate_dynamic_stack_check fixes it, but is probably not good
for all targets ;-)
50938 is still open.