[PATCH] D11660: [x86] reassociate integer multiplies using machine combiner pass

[Kevin B. Smith]

kbsmith1 added a comment.

Slight correction to my comment on the code.


================
Comment at: lib/Target/X86/X86InstrInfo.cpp:6312
@@ +6311,3 @@
+  if (Inst.getNumOperands() == 4)
+    if (!Inst.getOperand(3).isDead())
+      return false;
----------------
kbsmith1 wrote:
> Is there any possibility of 4 operand instructions where operand number 3 is dead, but is not EFLAGS?  It seems like a check  for (Inst.getOperand(3).isReg && Inst.getOperand(3).getReg() == X86::EFLAGS && !Inst.getOperand(3).isDead()) would be safer and more future proof.
My proposed code isn't really quite correct.  I think the correct formulation would be:
if (!Inst.getOperand(3).isReg() || Inst.getOperand(3).getReg() != X86::EFLAGS || !Inst.getOperand(3).isDead()) return false. 


http://reviews.llvm.org/D11660