if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
return BinaryOperator::CreateAnd(V, AndRHS);
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
return BinaryOperator::CreateAnd(V, AndRHS);
- // (A - N) & AndRHS -> -N & AndRHS where A & AndRHS == 0
- if (Op0I->hasOneUse() && MaskedValueIsZero(Op0LHS, AndRHSMask)) {
+ // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
+ // has 1's for all bits that the subtraction with A might affect.
+ if (Op0I->hasOneUse()) {
+ uint32_t BitWidth = AndRHSMask.getBitWidth();
+ uint32_t Zeros = AndRHSMask.countLeadingZeros();
+ APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
+
ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
- if (!A || !A->isZero()) {
+ if (!(A && A->isZero()) && // avoid infinite recursion.
+ MaskedValueIsZero(Op0LHS, Mask)) {
Instruction *NewNeg = BinaryOperator::CreateNeg(Op0RHS);
InsertNewInstBefore(NewNeg, I);
return BinaryOperator::CreateAnd(NewNeg, AndRHS);
}
}
Instruction *NewNeg = BinaryOperator::CreateNeg(Op0RHS);
InsertNewInstBefore(NewNeg, I);
return BinaryOperator::CreateAnd(NewNeg, AndRHS);
}
}
break;
case Instruction::Shl:
break;
case Instruction::Shl:
--- /dev/null
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {sub i32 0}
+; PR2330
+
+define i32 @foo(i32 %a) nounwind {
+entry:
+ %A = sub i32 5, %a
+ %B = and i32 %A, 2
+ ret i32 %B
+}