[LLVMdev] [x86 codegen] 3DNow! intrinsics not behaving as expected.

Michael Spencer bigcheesegs at gmail.com
Thu Apr 14 14:43:15 PDT 2011

On Thu, Apr 14, 2011 at 5:37 PM, Chris Lattner <clattner at apple.com> wrote:
> On Apr 14, 2011, at 12:47 PM, Eli Friedman wrote:
>>> I looked at the program using a debugger, and the pfadd instruction is
>>> executed correctly and the MMX register contains the correct values.
>>> The code that prepares the stack for the printf call seems to be
>>> messing it up.
>> I would call that "user error"; basically, using MMX instructions
>> messes up the FP stack, and we assume the user is smart enough to make
>> sure the two don't mix.
> More specifically, if you use MMX/3dNow intrinsics, you have to call "emms" at ABI boundaries.
> -Chris

Ok, now it makes sense. Thanks. Now that I know this is right, are
these patches ok to commit? Or should I post them to the llvm-commits,
and cfe-commits list?

- Michael Spencer

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