1 files changed, 15 insertions, 8 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index dd7ea14e8a89..4f71db1a4b09 100644
--- a/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -13,7 +13,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "InstCombine.h"
+#include "llvm/Support/PatternMatch.h"
 using namespace llvm;
+using namespace PatternMatch;
 
 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
 /// is to leave as a vector operation.  isConstant indicates whether we're
@@ -92,6 +94,13 @@ static Value *FindScalarElement(Value *V, unsigned EltNo) {
     return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
   }
 
+  // Extract a value from a vector add operation with a constant zero.
+  Value *Val = 0; Constant *Con = 0;
+  if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
+    if (Con->getAggregateElement(EltNo)->isNullValue())
+      return FindScalarElement(Val, EltNo);
+  }
+
   // Otherwise, we don't know.
   return 0;
 }
@@ -295,12 +304,12 @@ static Value *CollectShuffleElements(Value *V, SmallVectorImpl<Constant*> &Mask,
     Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
     return V;
   }
-  
+
   if (isa<ConstantAggregateZero>(V)) {
     Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
     return V;
   }
-  
+
   if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
     // If this is an insert of an extract from some other vector, include it.
     Value *VecOp    = IEI->getOperand(0);
@@ -595,12 +604,12 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   // ShuffleVectorInst is equivalent to the original one.
   for (unsigned i = 0; i < VWidth; ++i) {
     int eltMask;
-    if (Mask[i] == -1) {
+    if (Mask[i] < 0) {
       // This element is an undef value.
       eltMask = -1;
     } else if (Mask[i] < (int)LHSWidth) {
       // This element is from left hand side vector operand.
-      // 
+      //
       // If LHS is going to be replaced (case 1, 2, or 4), calculate the
       // new mask value for the element.
       if (newLHS != LHS) {
@@ -609,8 +618,7 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
         // with a -1 mask value.
         if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
           eltMask = -1;
-      }
-      else
+      } else
         eltMask = Mask[i];
     } else {
       // This element is from right hand side vector operand
@@ -630,8 +638,7 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
                  && "should have been check above");
           eltMask = -1;
         }
-      }
-      else
+      } else
         eltMask = Mask[i]-LHSWidth;
 
       // If LHS's width is changed, shift the mask value accordingly.