[PATCH] [X86] Special-case 2x CMOV when custom-inserting.

[Ahmed Bougacha]

Thanks for the review, will commit shortly!

-Ahmed


================
Comment at: lib/Target/X86/X86ISelLowering.cpp:18117
@@ +18116,3 @@
+  MachineInstr *NextCMOV = nullptr;
+  {
+    MachineBasicBlock::iterator InstrIt = MI;
----------------
MatzeB wrote:
> I'm probably missing something, but it seems unnecessary to me to open a new block.
Unnecessary yes, originally to hide the short-lived declarations.  I'll drop it.

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:18118-18119
@@ +18117,4 @@
+  {
+    MachineBasicBlock::iterator InstrIt = MI;
+    ++InstrIt;
+    if (InstrIt != BB->end() && InstrIt->getOpcode() == MI->getOpcode() &&
----------------
MatzeB wrote:
> MachineBasicBlock::iterator InstrIt = std::next(MI); ? I'd also choose a name like NextMIIt;
I don't think that works.  Since MI is a pointer, I'd expect that to be the same as
    (MI + 1)
which is different from
    &*(MBB::iterator(MI) + 1)

http://reviews.llvm.org/D8019

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