Fix an abort in instcombine when folding creates a vector rem instruction.

llvm-svn: 43743

llvm/lib/Transforms/Scalar/InstructionCombining.cpp

@@ -2622,6 +2622,7 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
   if (I.getType()->isInteger()) {
     APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
     if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+      // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
       return BinaryOperator::createUDiv(Op0, Op1, I.getName());
     }
   }      
@@ -2811,6 +2812,7 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
 
+  // Handle the integer rem common cases
   if (Instruction *common = commonIRemTransforms(I))
     return common;
   
@@ -2823,13 +2825,15 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
       return &I;
     }
  
-  // If the top bits of both operands are zero (i.e. we can prove they are
+  // If the sign bits of both operands are zero (i.e. we can prove they are
   // unsigned inputs), turn this into a urem.
+  if (I.getType()->isInteger()) {
     APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
     if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
       // X srem Y -> X urem Y, iff X and Y don't have sign bit set
       return BinaryOperator::createURem(Op0, Op1, I.getName());
     }
+  }
 
   return 0;
 }

llvm/test/Transforms/InstCombine/vector-srem.ll

@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {srem <4 x i32>}
+
+define <4 x i32> @foo(<4 x i32> %t, <4 x i32> %u)
+{
+  %k = sdiv <4 x i32> %t, %u
+  %l = mul <4 x i32> %k, %u
+  %m = sub <4 x i32> %t, %l
+  ret <4 x i32> %m
+}