mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-19 19:29:31 +00:00
Avoid creating garbage instructions, just move the old add instruction
to where we need it when converting -(A+B+C) -> -A + -B + -C. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23213 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
d6c69e9bba
commit
2cd85da3ed
@ -318,16 +318,18 @@ static Value *NegateValue(Value *V, Instruction *BI) {
|
||||
//
|
||||
if (Instruction *I = dyn_cast<Instruction>(V))
|
||||
if (I->getOpcode() == Instruction::Add && I->hasOneUse()) {
|
||||
Value *RHS = NegateValue(I->getOperand(1), BI);
|
||||
Value *LHS = NegateValue(I->getOperand(0), BI);
|
||||
// Push the negates through the add.
|
||||
I->setOperand(0, NegateValue(I->getOperand(0), BI));
|
||||
I->setOperand(1, NegateValue(I->getOperand(1), BI));
|
||||
|
||||
// We must actually insert a new add instruction here, because the neg
|
||||
// instructions do not dominate the old add instruction in general. By
|
||||
// adding it now, we are assured that the neg instructions we just
|
||||
// inserted dominate the instruction we are about to insert after them.
|
||||
// We must move the add instruction here, because the neg instructions do
|
||||
// not dominate the old add instruction in general. By moving it, we are
|
||||
// assured that the neg instructions we just inserted dominate the
|
||||
// instruction we are about to insert after them.
|
||||
//
|
||||
return BinaryOperator::create(Instruction::Add, LHS, RHS,
|
||||
I->getName()+".neg", BI);
|
||||
I->moveBefore(BI);
|
||||
I->setName(I->getName()+".neg");
|
||||
return I;
|
||||
}
|
||||
|
||||
// Insert a 'neg' instruction that subtracts the value from zero to get the
|
||||
|
Loading…
Reference in New Issue
Block a user