6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-21 02:24:22 +00:00
Code Issues Projects Releases Wiki Activity

[CodeGen] Teach the peephole optimizer to remember (and exploit) all folding

Browse Source 
opportunities in the current basic block, rather than just the last one seen.

<rdar://problem/16478629>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205481 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames
2014-04-02 22:59:58 +00:00
parent 5a61b72493
commit ed2154b816
2 changed files with 73 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

79
lib/CodeGen/PeepholeOptimizer.cpp
View File

@ -133,7 +133,8 @@ namespace {
bool foldImmediate(MachineInstr *MI, MachineBasicBlock *MBB,
SmallSet<unsigned, 4> &ImmDefRegs,
DenseMap<unsigned, MachineInstr*> &ImmDefMIs);
bool isLoadFoldable(MachineInstr *MI, unsigned &FoldAsLoadDefReg);
bool isLoadFoldable(MachineInstr *MI,
SmallSet<unsigned, 16> &FoldAsLoadDefCandidates);
};
}
@ -489,8 +490,9 @@ bool PeepholeOptimizer::optimizeCopyOrBitcast(MachineInstr *MI) {
/// isLoadFoldable - Check whether MI is a candidate for folding into a later
/// instruction. We only fold loads to virtual registers and the virtual
/// register defined has a single use.
bool PeepholeOptimizer::isLoadFoldable(MachineInstr *MI,
unsigned &FoldAsLoadDefReg) {
bool PeepholeOptimizer::isLoadFoldable(
MachineInstr *MI,
SmallSet<unsigned, 16> &FoldAsLoadDefCandidates) {
if (!MI->canFoldAsLoad() || !MI->mayLoad())
return false;
const MCInstrDesc &MCID = MI->getDesc();
@ -504,7 +506,7 @@ bool PeepholeOptimizer::isLoadFoldable(MachineInstr *MI,
if (!MI->getOperand(0).getSubReg() &&
TargetRegisterInfo::isVirtualRegister(Reg) &&
MRI->hasOneNonDBGUse(Reg)) {
FoldAsLoadDefReg = Reg;
FoldAsLoadDefCandidates.insert(Reg);
return true;
}
return false;
@ -570,18 +572,14 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
bool Changed = false;
SmallPtrSet<MachineInstr*, 8> LocalMIs;
SmallSet<unsigned, 4> ImmDefRegs;
DenseMap<unsigned, MachineInstr*> ImmDefMIs;
unsigned FoldAsLoadDefReg;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = &*I;
bool SeenMoveImm = false;
LocalMIs.clear();
ImmDefRegs.clear();
ImmDefMIs.clear();
FoldAsLoadDefReg = 0;
SmallPtrSet<MachineInstr*, 8> LocalMIs;
SmallSet<unsigned, 4> ImmDefRegs;
DenseMap<unsigned, MachineInstr*> ImmDefMIs;
SmallSet<unsigned, 16> FoldAsLoadDefCandidates;
for (MachineBasicBlock::iterator
MII = I->begin(), MIE = I->end(); MII != MIE; ) {
@ -595,15 +593,15 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
continue;
// If there exists an instruction which belongs to the following
// categories, we will discard the load candidate.
// categories, we will discard the load candidates.
if (MI->isPosition() || MI->isPHI() || MI->isImplicitDef() ||
MI->isKill() || MI->isInlineAsm() ||
MI->hasUnmodeledSideEffects()) {
FoldAsLoadDefReg = 0;
FoldAsLoadDefCandidates.clear();
continue;
}
if (MI->mayStore() || MI->isCall())
FoldAsLoadDefReg = 0;
FoldAsLoadDefCandidates.clear();
if (((MI->isBitcast() || MI->isCopy()) && optimizeCopyOrBitcast(MI)) ||
(MI->isCompare() && optimizeCmpInstr(MI, MBB)) ||
@ -630,30 +628,41 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
// Check whether MI is a load candidate for folding into a later
// instruction. If MI is not a candidate, check whether we can fold an
// earlier load into MI.
if (!isLoadFoldable(MI, FoldAsLoadDefReg) && FoldAsLoadDefReg) {
if (!isLoadFoldable(MI, FoldAsLoadDefCandidates) &&
!FoldAsLoadDefCandidates.empty()) {
// We need to fold load after optimizeCmpInstr, since optimizeCmpInstr
// can enable folding by converting SUB to CMP.
// Save FoldAsLoadDefReg because optimizeLoadInstr() resets it and we
// need it for markUsesInDebugValueAsUndef().
unsigned FoldedReg = FoldAsLoadDefReg;
MachineInstr *DefMI = 0;
MachineInstr *FoldMI = TII->optimizeLoadInstr(MI, MRI,
FoldAsLoadDefReg, DefMI);
if (FoldMI) {
// Update LocalMIs since we replaced MI with FoldMI and deleted DefMI.
DEBUG(dbgs() << "Replacing: " << *MI);
DEBUG(dbgs() << " With: " << *FoldMI);
LocalMIs.erase(MI);
LocalMIs.erase(DefMI);
LocalMIs.insert(FoldMI);
MI->eraseFromParent();
DefMI->eraseFromParent();
MRI->markUsesInDebugValueAsUndef(FoldedReg);
++NumLoadFold;
// MI is replaced with FoldMI.
Changed = true;
continue;
const MCInstrDesc &MIDesc = MI->getDesc();
for (unsigned i = MIDesc.getNumDefs(); i != MIDesc.getNumOperands();
++i) {
const MachineOperand &MOp = MI->getOperand(i);
if (!MOp.isReg())
continue;
unsigned TryFoldReg = MOp.getReg();
if (FoldAsLoadDefCandidates.count(TryFoldReg)) {
MachineInstr *DefMI = 0;
MachineInstr *FoldMI = TII->optimizeLoadInstr(MI, MRI, TryFoldReg,
DefMI);
if (FoldMI) {
// Update LocalMIs since we replaced MI with FoldMI and deleted
// DefMI.
DEBUG(dbgs() << "Replacing: " << *MI);
DEBUG(dbgs() << " With: " << *FoldMI);
LocalMIs.erase(MI);
LocalMIs.erase(DefMI);
LocalMIs.insert(FoldMI);
MI->eraseFromParent();
DefMI->eraseFromParent();
MRI->markUsesInDebugValueAsUndef(TryFoldReg);
FoldAsLoadDefCandidates.erase(TryFoldReg);
++NumLoadFold;
// MI is replaced with FoldMI.
Changed = true;
break;
}
}
}
}
}