[PATCH] D116072: [X86] GLC: Break false dependency for dest register for several instructions.

[Pei, Gen via Phabricator via llvm-commits]

gpei added a comment.
Herald added a project: All.

In D116072#3203977 <https://reviews.llvm.org/D116072#3203977>, @craig.topper wrote:

> Some of these are quite surprising to me especially PMULLQ. Can you provide any more explanation about why these have false dependencies?

Intel® 64 and IA-32 Architectures Optimization Reference Manual is updated, 2.2.1.4 Avoiding Destination False Dependency tells the details.



================
Comment at: llvm/lib/Target/X86/X86InstrInfo.cpp:5785
+      return;
+    // These instructions are all floating point domain, so vpxord is the best
+    // choice.
----------------
craig.topper wrote:
> This doesn't make sense. VPXORD is an integer instruction.
Yes, I copied the comments above. There is no VPXORPSZ128rr, is it acceptable I only delete my comments?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D116072/new/

https://reviews.llvm.org/D116072