Don't store COPY pointers in VNInfo.

If a value is defined by a COPY, that instuction can easily and cheaply
be found by getInstructionFromIndex(VNI->def).

This reduces the size of VNInfo from 24 to 16 bytes, and improves
llc compile time by 3%.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149763 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveRangeCalc.cpp b/lib/CodeGen/LiveRangeCalc.cpp
index 1d6c3c5..d8ab791 100644
--- a/lib/CodeGen/LiveRangeCalc.cpp
+++ b/lib/CodeGen/LiveRangeCalc.cpp
@@ -237,7 +237,7 @@
         assert(Alloc && "Need VNInfo allocator to create PHI-defs");
         SlotIndex Start, End;
         tie(Start, End) = Indexes->getMBBRange(MBB);
-        VNInfo *VNI = I->LI->getNextValue(Start, 0, *Alloc);
+        VNInfo *VNI = I->LI->getNextValue(Start, *Alloc);
         VNI->setIsPHIDef(true);
         I->Value = VNI;
         // This block is done, we know the final value.