[InstrInfo] Refactor foldOperandImpl to thread through InsertPt. NFC

Summary:
This was a longstanding FIXME and is a necessary precursor to cases
where foldOperandImpl may have to create more than one instruction
(e.g. to constrain a register class). This is the split out NFC changes from
D6262.

Reviewers: pete, ributzka, uweigand, mcrosier

Reviewed By: mcrosier

Subscribers: mcrosier, ted, llvm-commits

Differential Revision: http://reviews.llvm.org/D10174

llvm-svn: 239336
diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index d1d053a..3dc75d7 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -3530,9 +3530,9 @@
   SmallVector<MachineOperand, 8> AddrOps;
   AM.getFullAddress(AddrOps);
 
-  MachineInstr *Result =
-    XII.foldMemoryOperandImpl(*FuncInfo.MF, MI, OpNo, AddrOps,
-                              Size, Alignment, /*AllowCommute=*/true);
+  MachineInstr *Result = XII.foldMemoryOperandImpl(
+      *FuncInfo.MF, MI, OpNo, AddrOps, FuncInfo.InsertPt, Size, Alignment,
+      /*AllowCommute=*/true);
   if (!Result)
     return false;
 
@@ -3556,7 +3556,6 @@
   }
 
   Result->addMemOperand(*FuncInfo.MF, createMachineMemOperandFor(LI));
-  FuncInfo.MBB->insert(FuncInfo.InsertPt, Result);
   MI->eraseFromParent();
   return true;
 }