[llvm-commits] [llvm-gcc-4.2] r50200 - /llvm-gcc-4.2/trunk/gcc/testsuite/gcc.target/x86_64/abi/asm-support-darwin.s

[Chris Lattner]

On Apr 23, 2008, at 5:45 PM, Dan Gohman wrote:

>
> On Apr 23, 2008, at 5:35 PM, Chris Lattner wrote:
>>
>> On Apr 23, 2008, at 5:11 PM, Dan Gohman wrote:
>>
>>> Author: djg
>>> Date: Wed Apr 23 19:11:32 2008
>>> New Revision: 50200
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=50200&view=rev
>>> Log:
>>> Fix the darwin snapshot_ret to keep %rsp 16-byte aligned. This is
>>> pretty obscure, but it turns out that LLVM's -regalloc=local
>>> occasionally finds a way to need xmm spills in some of these trivial
>>> ABI testcases, and the code for that requires proper stack  
>>> alignment.
>>
>> Whoa.  What the heck is snapshot_ret used for?
>
> It's used by the ABI tests to wrap calls to functions
> with interesting return values. It "snapshots" the
> interesting register state immediately after the call
> for subsequent verification.

Ah, interesting.  Great catch.

-Chris