case Instruction::Sub:
return SE.getMinusSCEV(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));
+ case Instruction::And:
+ // For an expression like x&255 that merely masks off the high bits,
+ // use zext(trunc(x)) as the SCEV expression.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
+ const APInt &A = CI->getValue();
+ unsigned Ones = A.countTrailingOnes();
+ if (APIntOps::isMask(Ones, A))
+ return
+ SE.getZeroExtendExpr(SE.getTruncateExpr(getSCEV(U->getOperand(0)),
+ IntegerType::get(Ones)),
+ U->getType());
+ }
+ break;
case Instruction::Or:
// If the RHS of the Or is a constant, we may have something like:
// X*4+1 which got turned into X*4|1. Handle this as an Add so loop
}
break;
+ case Instruction::AShr:
+ // For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1)))
+ if (Instruction *L = dyn_cast<Instruction>(U->getOperand(0)))
+ if (L->getOpcode() == Instruction::Shl &&
+ L->getOperand(1) == U->getOperand(1)) {
+ uint64_t Amt = CI->getZExtValue();
+ return
+ SE.getSignExtendExpr(SE.getTruncateExpr(getSCEV(L->getOperand(0)),
+ IntegerType::get(Amt)),
+ U->getType());
+ }
+ break;
+
case Instruction::Trunc:
return SE.getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());