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Fold (X setcc C1) | (X setcc C2)

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This implements or.ll:test1[89]


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16561 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-09-28 22:33:08 +00:00
parent 0b948848eb
commit b4f40d2059
1 changed files with 102 additions and 1 deletions
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103
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1396,10 +1396,111 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
}
// (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
return R;
Value *LHSVal, *RHSVal;
ConstantInt *LHSCst, *RHSCst;
Instruction::BinaryOps LHSCC, RHSCC;
if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
// Set[GL]E X, CST is folded to Set[GL]T elsewhere.
LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
// Ensure that the larger constant is on the RHS.
Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
SetCondInst *LHS = cast<SetCondInst>(Op0);
if (cast<ConstantBool>(Cmp)->getValue()) {
std::swap(LHS, RHS);
std::swap(LHSCst, RHSCst);
std::swap(LHSCC, RHSCC);
}
// At this point, we know we have have two setcc instructions
// comparing a value against two constants and or'ing the result
// together. Because of the above check, we know that we only have
// SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
// FoldSetCCLogical check above), that the two constants are not
// equal.
assert(LHSCst != RHSCst && "Compares not folded above?");
switch (LHSCC) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetEQ:
switch (RHSCC) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetEQ:
if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
LHSVal->getName()+".off");
InsertNewInstBefore(Add, I);
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
}
break; // (X == 13 | X == 15) -> no change
case Instruction::SetGT:
if (LHSCst == SubOne(RHSCst)) // (X == 13 | X > 14) -> X > 13
return new SetCondInst(Instruction::SetGT, LHSVal, LHSCst);
break; // (X == 13 | X > 15) -> no change
case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
return ReplaceInstUsesWith(I, RHS);
}
break;
case Instruction::SetNE:
switch (RHSCC) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetLT: // (X != 13 | X < 15) -> X < 15
return ReplaceInstUsesWith(I, RHS);
case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
return ReplaceInstUsesWith(I, LHS);
case Instruction::SetNE: // (X != 13 | X != 15) -> true
return ReplaceInstUsesWith(I, ConstantBool::True);
}
break;
case Instruction::SetLT:
switch (RHSCC) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
break;
case Instruction::SetGT: {// (X < 13 | X > 15) -> (X-13) > 2
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
LHSVal->getName()+".off");
InsertNewInstBefore(Add, I);
// Convert to unsigned for the comparison.
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
AddCST = ConstantExpr::getAdd(AddCST, RHSCst);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
}
case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
return ReplaceInstUsesWith(I, RHS);
}
break;
case Instruction::SetGT:
switch (RHSCC) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
return ReplaceInstUsesWith(I, LHS);
case Instruction::SetNE: // (X > 13 | X != 15) -> true
case Instruction::SetLT: // (X > 13 | X < 15) -> true
return ReplaceInstUsesWith(I, ConstantBool::True);
}
}
}
}
return Changed ? &I : 0;
}