break;
}
case Instruction::BitCast:
- if (!I->getOperand(0)->getType()->isInteger())
+ if (!I->getOperand(0)->getType()->isIntOrIntVector())
return false; // vector->int or fp->int?
+
+ if (const VectorType *DstVTy = dyn_cast<VectorType>(I->getType())) {
+ if (const VectorType *SrcVTy =
+ dyn_cast<VectorType>(I->getOperand(0)->getType())) {
+ if (DstVTy->getNumElements() != SrcVTy->getNumElements())
+ // Don't touch a bitcast between vectors of different element counts.
+ return false;
+ } else
+ // Don't touch a scalar-to-vector bitcast.
+ return false;
+ } else if (isa<VectorType>(I->getOperand(0)->getType()))
+ // Don't touch a vector-to-scalar bitcast.
+ return false;
+
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
RHSKnownZero, RHSKnownOne, Depth+1))
return I;
--- /dev/null
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i32 0}
+; PR4487
+
+; Bitcasts between vectors and scalars are valid, despite being ill-advised.
+
+define i32 @test(i64 %a) {
+bb20:
+ %t1 = bitcast i64 %a to <2 x i32>
+ %t2 = bitcast i64 %a to <2 x i32>
+ %t3 = xor <2 x i32> %t1, %t2
+ %t4 = extractelement <2 x i32> %t3, i32 0
+ ret i32 %t4
+}
+