diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp | 76 |
1 files changed, 44 insertions, 32 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp b/contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp index 3b15a0a..60ae374 100644 --- a/contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp +++ b/contrib/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp @@ -18,29 +18,6 @@ using namespace llvm; -/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits -/// are carefully arranged to allow folding of expressions such as: -/// -/// (A < B) | (A > B) --> (A != B) -/// -/// Note that this is only valid if the first and second predicates have the -/// same sign. Is illegal to do: (A u< B) | (A s> B) -/// -/// Three bits are used to represent the condition, as follows: -/// 0 A > B -/// 1 A == B -/// 2 A < B -/// -/// <=> Value Definition -/// 000 0 Always false -/// 001 1 A > B -/// 010 2 A == B -/// 011 3 A >= B -/// 100 4 A < B -/// 101 5 A != B -/// 110 6 A <= B -/// 111 7 Always true -/// unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) { ICmpInst::Predicate Pred = InvertPred ? ICI->getInversePredicate() : ICI->getPredicate(); @@ -62,13 +39,6 @@ unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) { } } -/// getICmpValue - This is the complement of getICmpCode, which turns an -/// opcode and two operands into either a constant true or false, or the -/// predicate for a new ICmp instruction. The sign is passed in to determine -/// which kind of predicate to use in the new icmp instruction. -/// Non-NULL return value will be a true or false constant. -/// NULL return means a new ICmp is needed. The predicate for which is -/// output in NewICmpPred. Value *llvm::getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, CmpInst::Predicate &NewICmpPred) { switch (Code) { @@ -87,10 +57,52 @@ Value *llvm::getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, return nullptr; } -/// PredicatesFoldable - Return true if both predicates match sign or if at -/// least one of them is an equality comparison (which is signless). bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) { return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) || (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; +} |
