6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-14 11:32:34 +00:00
Code Issues Projects Releases Wiki Activity

Add two optimizations. The first folds (X+Y)-X -> Y

Browse Source 
The second folds operations into selects, e.g. (select C, (X+Y), (Y+Z))
-> (Y+(select C, X, Z)

This occurs a few times across spec, e.g.

         select    add/sub
mesa:    83        0
povray:  5         2
gcc      4         2
parser   0         22
perlbmk  13        30
twolf    0         3


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19706 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-19 21:50:18 +00:00
parent d4dd775a24
commit 6fb5a4a5f8
1 changed files with 89 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

91
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -120,6 +120,8 @@ namespace {
Instruction::BinaryOps Cond, Instruction &I);
Instruction *visitShiftInst(ShiftInst &I);
Instruction *visitCastInst(CastInst &CI);
Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
Instruction *FI);
Instruction *visitSelectInst(SelectInst &CI);
Instruction *visitCallInst(CallInst &CI);
Instruction *visitInvokeInst(InvokeInst &II);
@ -833,6 +835,14 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
}
}
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
if (Op0I->getOpcode() == Instruction::Add)
if (!Op0->getType()->isFloatingPoint()) {
if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
return ReplaceInstUsesWith(I, Op0I->getOperand(1));
else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
return ReplaceInstUsesWith(I, Op0I->getOperand(0));
}
ConstantInt *C1;
if (Value *X = dyn_castFoldableMul(Op0, C1)) {
@ -3496,6 +3506,78 @@ static Constant *GetSelectFoldableConstant(Instruction *I) {
}
}
/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
/// have the same opcode and only one use each. Try to simplify this.
Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
Instruction *FI) {
if (TI->getNumOperands() == 1) {
// If this is a non-volatile load or a cast from the same type,
// merge.
if (TI->getOpcode() == Instruction::Cast) {
if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
return 0;
} else {
return 0; // unknown unary op.
}
// Fold this by inserting a select from the input values.
SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
FI->getOperand(0), SI.getName()+".v");
InsertNewInstBefore(NewSI, SI);
return new CastInst(NewSI, TI->getType());
}
// Only handle binary operators here.
if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
return 0;
// Figure out if the operations have any operands in common.
Value *MatchOp, *OtherOpT, *OtherOpF;
bool MatchIsOpZero;
if (TI->getOperand(0) == FI->getOperand(0)) {
MatchOp = TI->getOperand(0);
OtherOpT = TI->getOperand(1);
OtherOpF = FI->getOperand(1);
MatchIsOpZero = true;
} else if (TI->getOperand(1) == FI->getOperand(1)) {
MatchOp = TI->getOperand(1);
OtherOpT = TI->getOperand(0);
OtherOpF = FI->getOperand(0);
MatchIsOpZero = false;
} else if (!TI->isCommutative()) {
return 0;
} else if (TI->getOperand(0) == FI->getOperand(1)) {
MatchOp = TI->getOperand(0);
OtherOpT = TI->getOperand(1);
OtherOpF = FI->getOperand(0);
MatchIsOpZero = true;
} else if (TI->getOperand(1) == FI->getOperand(0)) {
MatchOp = TI->getOperand(1);
OtherOpT = TI->getOperand(0);
OtherOpF = FI->getOperand(1);
MatchIsOpZero = true;
} else {
return 0;
}
// If we reach here, they do have operations in common.
SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
OtherOpF, SI.getName()+".v");
InsertNewInstBefore(NewSI, SI);
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
if (MatchIsOpZero)
return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
else
return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
} else {
if (MatchIsOpZero)
return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
else
return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
}
}
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
Value *CondVal = SI.getCondition();
Value *TrueVal = SI.getTrueValue();
@ -3616,14 +3698,19 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
}
}
// Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is legal for
// FP as well.
if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
if (TI->hasOneUse() && FI->hasOneUse()) {
bool isInverse = false;
Instruction *AddOp = 0, *SubOp = 0;
// Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
if (TI->getOpcode() == FI->getOpcode())
if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
return IV;
// Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
// even legal for FP.
if (TI->getOpcode() == Instruction::Sub &&
FI->getOpcode() == Instruction::Add) {
AddOp = FI; SubOp = TI;