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

[Dan Gohman]

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.

Dan