Value *V = InsertCastBefore(SrcI->getOperand(0), Ty, CI);
return new ShiftInst(Instruction::LShr, V, SrcI->getOperand(1));
}
+ } else { // This is a variable shr.
+
+ // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
+ // more LLVM instructions, but allows '1 << Y' to be hoisted if
+ // loop-invariant and CSE'd.
+ if (CI.getType() == Type::BoolTy && SrcI->hasOneUse()) {
+ Value *One = ConstantInt::get(SrcI->getType(), 1);
+
+ Value *V = InsertNewInstBefore(new ShiftInst(Instruction::Shl, One,
+ SrcI->getOperand(1),
+ "tmp"), CI);
+ V = InsertNewInstBefore(BinaryOperator::createAnd(V,
+ SrcI->getOperand(0),
+ "tmp"), CI);
+ Value *Zero = Constant::getNullValue(V->getType());
+ return BinaryOperator::createSetNE(V, Zero);
+ }
}
break;
}