diff options
Diffstat (limited to 'lib/Transforms')
-rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 7989ebf..b059c49 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2130,6 +2130,67 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return new PtrToIntInst(I2, CI->getType()); } } + + // add (select (icmp 0 (sub m A)) X Y) A -> + // add (select (icmp A m) X Y) A + // + // add (select X 0 (sub n A)) A -> + // select X A n -> + { + SelectInst *SI = dyn_cast<SelectInst>(LHS); + Value *Other = RHS; + if (!SI) { + SI = dyn_cast<SelectInst>(RHS); + Other = LHS; + } + if (SI) { + Value *TV = SI->getTrueValue(); + Value *FV = SI->getFalseValue(); + Value *A; + + // Can we fold the add into the argument of the compare? + Value *Cond = SI->getCondition(); + if (ICmpInst *IC = dyn_cast<ICmpInst>(Cond)) { + Value *ICOp0 = IC->getOperand(0); + Value *ICOp1 = IC->getOperand(1); + ConstantInt *C3, *C4; + + // Check both arguments of the compare for a matching subtract. + if (match(ICOp0, m_ConstantInt(C3)) && C3->getValue() == 0 && + match(ICOp1, m_Sub(m_ConstantInt(C4), m_Value(A))) && + A == Other) { + // We managed to fold the add into the RHS of the select condition. + Cond = new ICmpInst(IC->getPredicate(), A, C4, "asis", SI); + } else if (match(ICOp1, m_ConstantInt(C3)) && C3->getValue() == 0 && + match(ICOp0, m_Sub(m_ConstantInt(C4), m_Value(A))) && + A == Other) { + // We managed to fold the add into the LHS of the select condition. + Cond = new ICmpInst(IC->getPredicate(), C4, A, "asis", SI); + } + } + + // Can we fold the add into the argument of the select? + // We check both true and false select arguments for a matching subtract. + ConstantInt *C1, *C2; + if (match(FV, m_ConstantInt(C1)) && C1->getValue() == 0 && + match(TV, m_Sub(m_ConstantInt(C2), m_Value(A))) && + A == Other) { + // We managed to fold the add into the true select value, + // picking up a simplified condition, if available. + return new SelectInst(Cond, C2, A, "adselsub"); + } else if (match(TV, m_ConstantInt(C1)) && C1->getValue() == 0 && + match(FV, m_Sub(m_ConstantInt(C2), m_Value(A))) && + A == Other) { + // We managed to fold the add into the false select value, + // picking up a simplified condition, if available. + return new SelectInst(Cond, A, C2, "adselsub"); + } else if (Cond != SI->getCondition()) { + // We only managed to fold the add into the select condition. + SI->setOperand(0, Cond); + Changed = true; + } + } + } return Changed ? &I : 0; } |