Add support for folding binary operators with vector zero operands.

llvm-svn: 43510

llvm/lib/VMCore/ConstantFold.cpp

@@ -450,14 +450,20 @@ Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
 
 /// EvalVectorOp - Given two vector constants and a function pointer, apply the
 /// function pointer to each element pair, producing a new ConstantVector
-/// constant.
+/// constant. Either or both of V1 and V2 may be NULL, meaning a
+/// ConstantAggregateZero operand.
 static Constant *EvalVectorOp(const ConstantVector *V1, 
                               const ConstantVector *V2,
+                              const VectorType *VTy,
                               Constant *(*FP)(Constant*, Constant*)) {
   std::vector<Constant*> Res;
-  for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
+  const Type *EltTy = VTy->getElementType();
-    Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
+  for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
-                     const_cast<Constant*>(V2->getOperand(i))));
+    const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy);
+    const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy);
+    Res.push_back(FP(const_cast<Constant*>(C1),
+                     const_cast<Constant*>(C2)));
+  }
   return ConstantVector::get(Res);
 }
 
@@ -707,36 +713,40 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
         return ConstantFP::get(CFP1->getType(), C3V);
       }
     }
-  } else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {
+  } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) {
-    if (const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2)) {
+    const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1);
+    const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2);
+    assert((CP1 != NULL || isa<ConstantAggregateZero>(C1)) &&
+           "Unexpected kind of vector constant!");
+    assert((CP2 != NULL || isa<ConstantAggregateZero>(C2)) &&
+           "Unexpected kind of vector constant!");
       switch (Opcode) {
         default:
           break;
         case Instruction::Add: 
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getAdd);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd);
         case Instruction::Sub: 
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getSub);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub);
         case Instruction::Mul: 
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getMul);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul);
         case Instruction::UDiv:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getUDiv);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv);
         case Instruction::SDiv:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getSDiv);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv);
         case Instruction::FDiv:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getFDiv);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv);
         case Instruction::URem:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getURem);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem);
         case Instruction::SRem:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getSRem);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem);
         case Instruction::FRem:
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getFRem);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem);
         case Instruction::And: 
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getAnd);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd);
         case Instruction::Or:  
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getOr);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr);
         case Instruction::Xor: 
-          return EvalVectorOp(CP1, CP2, ConstantExpr::getXor);
+        return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor);
-      }
     }
   }
 

llvm/test/Transforms/InstCombine/fold-vector-zero.ll

@@ -0,0 +1,35 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep zeroinitializer
+
+define void @foo(i64 %A, i64 %B) {
+bb8:
+	br label %bb30
+
+bb30:
+	%s0 = phi i64 [ 0, %bb8 ], [ %r21, %bb30 ]
+	%l0 = phi i64 [ -2222, %bb8 ], [ %r23, %bb30 ]
+	%r2 = add i64 %s0, %B
+	%r3 = inttoptr i64 %r2 to <2 x double>*
+	%r4 = load <2 x double>* %r3, align 8
+	%r6 = bitcast <2 x double> %r4 to <2 x i64>
+	%r7 = bitcast <2 x double> zeroinitializer to <2 x i64>
+	%r8 = insertelement <2 x i64> undef, i64 9223372036854775807, i32 0
+	%r9 = insertelement <2 x i64> undef, i64 -9223372036854775808, i32 0
+	%r10 = insertelement <2 x i64> %r8, i64 9223372036854775807, i32 1
+	%r11 = insertelement <2 x i64> %r9, i64 -9223372036854775808, i32 1
+	%r12 = and <2 x i64> %r6, %r10
+	%r13 = and <2 x i64> %r7, %r11
+	%r14 = or <2 x i64> %r12, %r13
+	%r15 = bitcast <2 x i64> %r14 to <2 x double>
+	%r18 = add i64 %s0, %A
+	%r19 = inttoptr i64 %r18 to <2 x double>*
+	store <2 x double> %r15, <2 x double>* %r19, align 8
+	%r21 = add i64 16, %s0
+	%r23 = add i64 1, %l0
+	%r25 = icmp slt i64 %r23, 0
+	%r26 = zext i1 %r25 to i64
+	%r27 = icmp ne i64 %r26, 0
+	br i1 %r27, label %bb30, label %bb5
+
+bb5:
+	ret void
+}