1 files changed, 12 insertions, 2 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 88ee1453fa..1ffcc2b122 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -462,8 +462,8 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
   
   // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
   Value *A = 0; ConstantInt *Cst = 0;
-  if (match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst))) &&
-      Src->hasOneUse()) {
+  if (Src->hasOneUse() &&
+      match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
     // We have three types to worry about here, the type of A, the source of
     // the truncate (MidSize), and the destination of the truncate. We know that
     // ASize < MidSize   and MidSize > ResultSize, but don't know the relation
@@ -482,6 +482,16 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
     Shift->takeName(Src);
     return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
   }
+  
+  // Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
+  // type isn't non-native.
+  if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) &&
+      ShouldChangeType(Src->getType(), CI.getType()) &&
+      match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
+    Value *NewTrunc = Builder->CreateTrunc(A, CI.getType(), A->getName()+".tr");
+    return BinaryOperator::CreateAnd(NewTrunc,
+                                     ConstantExpr::getTrunc(Cst, CI.getType()));
+  }
 
   return 0;
 }