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Eliminate some simple dead X/Y loops

This commit is contained in:
drmortalwombat 2023-10-16 21:51:20 +02:00
parent f5c13c02af
commit 9e3b014927
2 changed files with 62 additions and 0 deletions
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61
oscar64/NativeCodeGenerator.cpp
View File

@ -16088,6 +16088,60 @@ bool NativeCodeBasicBlock::Split16BitLoopCount(NativeCodeProcedure* proc)
return changed;
}
bool NativeCodeBasicBlock::EliminateDeadLoops(void)
{
bool changed = false;
if (!mVisited)
{
mVisited = true;
if (mLoopHead && mNumEntries == 2 && mFalseJump)
{
NativeCodeBasicBlock* eblock = nullptr;
if (mTrueJump == this)
eblock = mFalseJump;
else if (mFalseJump == this)
eblock = mTrueJump;
if (eblock)
{
if (mIns.Size() == 2 && (mIns[0].mType == ASMIT_INX || mIns[0].mType == ASMIT_DEX) && mIns[1].mType == ASMIT_CPX)
{
if (!(eblock->mEntryRequiredRegs[CPU_REG_X]))
{
mLoopHead = false;
mTrueJump = eblock;
mBranch = ASMIT_JMP;
mEntryBlocks.RemoveAll(this);
mNumEntries--;
changed = true;
}
}
else if (mIns.Size() == 2 && (mIns[0].mType == ASMIT_INY || mIns[0].mType == ASMIT_DEY) && mIns[1].mType == ASMIT_CPY)
{
if (!(eblock->mEntryRequiredRegs[CPU_REG_Y]))
{
mLoopHead = false;
mTrueJump = eblock;
mBranch = ASMIT_JMP;
mEntryBlocks.RemoveAll(this);
mNumEntries--;
changed = true;
}
}
}
}
if (mTrueJump && mTrueJump->EliminateDeadLoops())
changed = true;
if (mFalseJump && mFalseJump->EliminateDeadLoops())
changed = true;
}
return changed;
}
bool NativeCodeBasicBlock::CrossBlockStoreLoadBypass(NativeCodeProcedure* proc)
{
bool changed = false;
@ -43115,6 +43169,13 @@ void NativeCodeProcedure::Optimize(void)
changed = true;
}
if (step >= 9)
{
ResetVisited();
if (mEntryBlock->EliminateDeadLoops())
changed = true;
}
#if _DEBUG
ResetVisited();
mEntryBlock->CheckBlocks();

1
oscar64/NativeCodeGenerator.h
View File

@ -584,6 +584,7 @@ public:
bool SimplifyDiamond(NativeCodeProcedure* proc);
bool SimplifyLoopEnd(NativeCodeProcedure* proc);
bool CrossBlockStoreLoadBypass(NativeCodeProcedure* proc);
bool EliminateDeadLoops(void);
bool CanBytepassLoad(const NativeCodeInstruction& ains, int from = 0) const;
bool CanHoistStore(const NativeCodeInstruction& ains) const;