[cfe-commits] Alignment of return from __builtin_alloca

David Sehr sehr at google.com
Thu Jun 7 15:08:35 PDT 2012

Please disregard my last comment.  Implementing that will be a bit
challenging, as stackAlign is a back end value rather than a clang
TargetInfo value. Are there targets where stackAlign < SuitableAlign?


On Thu, Jun 7, 2012 at 2:57 PM, David Sehr <sehr at google.com> wrote:
> Joerg,
> So the interesting case is where stackAlignment < SuitableAlignment.
> Would it be reasonable with you to align to the minimum of those two?
> David
> On Thu, Jun 7, 2012 at 2:40 PM, Joerg Sonnenberger
> <joerg at britannica.bec.de> wrote:
>> On Thu, Jun 07, 2012 at 02:23:13PM -0700, David Sehr wrote:
>>> I have recently been debugging a failure with one of the tests from
>>> the gcc torture test suite and discovered that gcc and llvm seem to
>>> differ on whether __builtin_alloca is aligned more than 0mod4 (gcc
>>> thinks it's aligned by what clang stores inTargetInfo::SuitableAlign).
>> It should ensure that the stack alignment invariance from the ABI is
>> honored. I don't think it should provide a stricter alignment.
>> Please be very careful when changing this to not violate the above.
>> Joerg
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