diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineInternal.h')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineInternal.h | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h index fc0a1e90d38..bf0ffe9d242 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h +++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h @@ -139,6 +139,8 @@ static inline Constant *SubOne(Constant *C) { /// This happens in cases where the ~ can be eliminated. If WillInvertAllUses /// is true, work under the assumption that the caller intends to remove all /// uses of V and only keep uses of ~V. +/// +/// See also: canFreelyInvertAllUsersOf() static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) { // ~(~(X)) -> X. if (match(V, m_Not(m_Value()))) @@ -168,6 +170,32 @@ static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) { return false; } +/// Given i1 V, can every user of V be freely adapted if V is changed to !V ? +/// +/// See also: IsFreeToInvert() +static inline bool canFreelyInvertAllUsersOf(Value *V, Value *IgnoredUser) { + // Look at every user of V. + for (User *U : V->users()) { + if (U == IgnoredUser) + continue; // Don't consider this user. + + auto *I = cast<Instruction>(U); + switch (I->getOpcode()) { + case Instruction::Select: + case Instruction::Br: + break; // Free to invert by swapping true/false values/destinations. + case Instruction::Xor: // Can invert 'xor' if it's a 'not', by ignoring it. + if (!match(I, m_Not(m_Value()))) + return false; // Not a 'not'. + break; + default: + return false; // Don't know, likely not freely invertible. + } + // So far all users were free to invert... + } + return true; // Can freely invert all users! +} + /// Some binary operators require special handling to avoid poison and undefined /// behavior. If a constant vector has undef elements, replace those undefs with /// identity constants if possible because those are always safe to execute. @@ -540,7 +568,7 @@ private: Value *foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction &CxtI); Value *foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction &CxtI); - Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS); + Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &I); /// Optimize (fcmp)&(fcmp) or (fcmp)|(fcmp). /// NOTE: Unlike most of instcombine, this returns a Value which should |
