/// equality comparison (which is signless).
bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2);
+ /// Decompose an icmp into the form ((X & Y) pred Z) if possible. The returned
+ /// predicate is either == or !=. Returns false if decomposition fails.
+ bool decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
+ Value *&X, Value *&Y, Value *&Z);
+
} // end namespace llvm
#endif
return NewMask;
}
-/// Decompose an icmp into the form ((X & Y) pred Z) if possible.
-/// The returned predicate is either == or !=. Returns false if
-/// decomposition fails.
-static bool decomposeBitTestICmp(const ICmpInst *I, ICmpInst::Predicate &Pred,
- Value *&X, Value *&Y, Value *&Z) {
- ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
- if (!C)
- return false;
-
- switch (I->getPredicate()) {
- default:
- return false;
- case ICmpInst::ICMP_SLT:
- // X < 0 is equivalent to (X & SignBit) != 0.
- if (!C->isZero())
- return false;
- Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
- Pred = ICmpInst::ICMP_NE;
- break;
- case ICmpInst::ICMP_SGT:
- // X > -1 is equivalent to (X & SignBit) == 0.
- if (!C->isAllOnesValue())
- return false;
- Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
- Pred = ICmpInst::ICMP_EQ;
- break;
- case ICmpInst::ICMP_ULT:
- // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
- if (!C->getValue().isPowerOf2())
- return false;
- Y = ConstantInt::get(I->getContext(), -C->getValue());
- Pred = ICmpInst::ICMP_EQ;
- break;
- case ICmpInst::ICMP_UGT:
- // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
- if (!(C->getValue() + 1).isPowerOf2())
- return false;
- Y = ConstantInt::get(I->getContext(), ~C->getValue());
- Pred = ICmpInst::ICMP_NE;
- break;
- }
-
- X = I->getOperand(0);
- Z = ConstantInt::getNullValue(C->getType());
- return true;
-}
-
/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
/// Return the set of pattern classes (from MaskedICmpType)
/// that both LHS and RHS satisfy.
(CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
(CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
}
+
+bool llvm::decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
+ Value *&X, Value *&Y, Value *&Z) {
+ ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
+ if (!C)
+ return false;
+
+ switch (I->getPredicate()) {
+ default:
+ return false;
+ case ICmpInst::ICMP_SLT:
+ // X < 0 is equivalent to (X & SignBit) != 0.
+ if (!C->isZero())
+ return false;
+ Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
+ Pred = ICmpInst::ICMP_NE;
+ break;
+ case ICmpInst::ICMP_SGT:
+ // X > -1 is equivalent to (X & SignBit) == 0.
+ if (!C->isAllOnesValue())
+ return false;
+ Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
+ Pred = ICmpInst::ICMP_EQ;
+ break;
+ case ICmpInst::ICMP_ULT:
+ // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
+ if (!C->getValue().isPowerOf2())
+ return false;
+ Y = ConstantInt::get(I->getContext(), -C->getValue());
+ Pred = ICmpInst::ICMP_EQ;
+ break;
+ case ICmpInst::ICMP_UGT:
+ // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
+ if (!(C->getValue() + 1).isPowerOf2())
+ return false;
+ Y = ConstantInt::get(I->getContext(), ~C->getValue());
+ Pred = ICmpInst::ICMP_NE;
+ break;
+ }
+
+ X = I->getOperand(0);
+ Z = ConstantInt::getNullValue(C->getType());
+ return true;
+}