Merging r216891:

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r216891 | majnemer | 2014-09-01 14:20:14 -0700 (Mon, 01 Sep 2014) | 12 lines

SROA: Don't insert instructions before a PHI

SROA may decide that it needs to insert a bitcast and would set it's
insertion point before a PHI.  This will create an invalid module
right quick.

Instead, choose the first insertion point in the basic block that holds
our PHI.

This fixes PR20822.

Differential Revision: http://reviews.llvm.org/D5141
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@223639 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SROA.cpp

@@ -2697,7 +2697,10 @@ private:
     // the old pointer, which necessarily must be in the right position to
     // dominate the PHI.
     IRBuilderTy PtrBuilder(IRB);
-    PtrBuilder.SetInsertPoint(OldPtr);
+    if (isa<PHINode>(OldPtr))
+      PtrBuilder.SetInsertPoint(OldPtr->getParent()->getFirstInsertionPt());
+    else
+      PtrBuilder.SetInsertPoint(OldPtr);
     PtrBuilder.SetCurrentDebugLocation(OldPtr->getDebugLoc());
 
     Value *NewPtr = getNewAllocaSlicePtr(PtrBuilder, OldPtr->getType());