[PATCH] D18246: X86: Use push-pop for materializing 8-bit immediates for minsize (take 2)

Hans Wennborg via llvm-commits llvm-commits at lists.llvm.org
Thu Mar 24 11:18:08 PDT 2016

hans added a comment.

In http://reviews.llvm.org/D18246#382637, @DavidKreitzer wrote:

> FWIW, here is a link to the change set for the original commit of the push/pop optimization: http://reviews.llvm.org/D15549. I just diffed that patch against this new one for the purpose of easier review.

Oops, it seems like I linked to the wrong one in the description of this patch.

Comment at: lib/Target/X86/X86InstrInfo.cpp:5369
@@ +5368,3 @@
+    MachineFrameInfo *MFI = MBB.getParent()->getFrameInfo();
+    if (!(Fn->hasFnAttribute(Attribute::NoRedZone) || MFI->adjustsStack() ||
+          IsWin64CC)) {
DavidKreitzer wrote:
> This code runs after the red-zone decision has been made, right? Would it be better to capture that decision as part of the MFI and do a more accurate "uses red zone" check here?
> If you agree but don't want to make that change now, a FIXME comment would be helpful.
I wasn't sure how to do this, but I think I've found a way. I'll upload a new patch.


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