Add a missing SCEV simplification sext(zext x) --> zext x.

[oota-llvm.git] / lib / Analysis / ScalarEvolution.cpp

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index b3df92611950e895a03e5d0d876098b4992fc335..ce0418849094b9d86175771682f6a1909fb6371d 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -994,6 +994,10 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
   if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
     return getSignExtendExpr(SS->getOperand(), Ty);
 
+  // sext(zext(x)) --> zext(x)
+  if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
+    return getZeroExtendExpr(SZ->getOperand(), Ty);
+
   // Before doing any expensive analysis, check to see if we've already
   // computed a SCEV for this Op and Ty.
   FoldingSetNodeID ID;