[SCEV] teach SCEV symbolical execution about overflow intrinsics folding.
Differential Revision: https://reviews.llvm.org/D64422

llvm-svn: 365726
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index a512834..20231ca 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1036,6 +1036,9 @@
     return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
   case Instruction::ExtractElement:
     return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
+  case Instruction::ExtractValue:
+    return ConstantExpr::getExtractValue(
+        Ops[0], dyn_cast<ExtractValueInst>(InstOrCE)->getIndices());
   case Instruction::InsertElement:
     return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
   case Instruction::ShuffleVector: