1 files changed, 31 insertions, 17 deletions

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index 1d293ccbd44dc..3aab0cce37e4f 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -208,6 +208,22 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
     }
   }
 
+  // If the cast operand is a constant vector, perform the cast by
+  // operating on each element. In the cast of bitcasts, the element
+  // count may be mismatched; don't attempt to handle that here.
+  if (const ConstantVector *CV = dyn_cast<ConstantVector>(V))
+    if (isa<VectorType>(DestTy) &&
+        cast<VectorType>(DestTy)->getNumElements() ==
+        CV->getType()->getNumElements()) {
+      std::vector<Constant*> res;
+      const VectorType *DestVecTy = cast<VectorType>(DestTy);
+      const Type *DstEltTy = DestVecTy->getElementType();
+      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
+        res.push_back(ConstantExpr::getCast(opc,
+                                            CV->getOperand(i), DstEltTy));
+      return ConstantVector::get(DestVecTy, res);
+    }
+
   // We actually have to do a cast now. Perform the cast according to the
   // opcode specified.
   switch (opc) {
@@ -237,14 +253,6 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
       APInt Val(DestBitWidth, 2, x);
       return ConstantInt::get(Val);
     }
-    if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
-      std::vector<Constant*> res;
-      const VectorType *DestVecTy = cast<VectorType>(DestTy);
-      const Type *DstEltTy = DestVecTy->getElementType();
-      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
-        res.push_back(ConstantExpr::getCast(opc, CV->getOperand(i), DstEltTy));
-      return ConstantVector::get(DestVecTy, res);
-    }
     return 0; // Can't fold.
   case Instruction::IntToPtr:   //always treated as unsigned
     if (V->isNullValue())       // Is it an integral null value?
@@ -266,14 +274,6 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
                                  APFloat::rmNearestTiesToEven);
       return ConstantFP::get(apf);
     }
-    if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
-      std::vector<Constant*> res;
-      const VectorType *DestVecTy = cast<VectorType>(DestTy);
-      const Type *DstEltTy = DestVecTy->getElementType();
-      for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
-        res.push_back(ConstantExpr::getCast(opc, CV->getOperand(i), DstEltTy));
-      return ConstantVector::get(DestVecTy, res);
-    }
     return 0;
   case Instruction::ZExt:
     if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
@@ -629,7 +629,7 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
     }
   }
 
-  // Handle simplifications of the RHS when a constant int.
+  // Handle simplifications when the RHS is a constant int.
   if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
     switch (Opcode) {
     case Instruction::Add:
@@ -773,6 +773,20 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
       }
       }
     }
+
+    switch (Opcode) {
+    case Instruction::SDiv:
+    case Instruction::UDiv:
+    case Instruction::URem:
+    case Instruction::SRem:
+    case Instruction::LShr:
+    case Instruction::AShr:
+    case Instruction::Shl:
+      if (CI1->equalsInt(0)) return const_cast<Constant*>(C1);
+      break;
+    default:
+      break;
+    }
   } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
     if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
       APFloat C1V = CFP1->getValueAPF();