Teach the constant folder how to do select instructions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12321 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index 5f7e0ef1b8..db21bd3d78 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -582,6 +582,17 @@ Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
   }
 }
 
+Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
+                                              const Constant *V1,
+                                              const Constant *V2) {
+  if (Cond == ConstantBool::True)
+    return const_cast<Constant*>(V1);
+  else if (Cond == ConstantBool::False)
+    return const_cast<Constant*>(V2);
+  return 0;
+}
+
+
 /// IdxCompare - Compare the two constants as though they were getelementptr
 /// indices.  This allows coersion of the types to be the same thing.
 ///