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variable folding #28

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variable folding #28

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1 change: 1 addition & 0 deletions include/Jitter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -290,6 +290,7 @@ namespace Jitter

void Compile();

bool VariableFolding(StatementList&);
bool ConstantFolding(StatementList&);
bool ConstantPropagation(StatementList&);
bool CopyPropagation(StatementList&);
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78 changes: 78 additions & 0 deletions src/Jitter_Optimize.cpp
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Expand Up @@ -170,6 +170,7 @@ void CJitter::Compile()
while(1)
{
bool dirty = false;
dirty |= VariableFolding(versionedStatements.statements);
dirty |= ConstantPropagation(versionedStatements.statements);
dirty |= ConstantFolding(versionedStatements.statements);
dirty |= CopyPropagation(versionedStatements.statements);
Expand Down Expand Up @@ -827,6 +828,83 @@ bool CJitter::FoldConstant12832Operation(STATEMENT& statement)
return changed;
}

bool CJitter::VariableFolding(StatementList& statements)
{
auto changed = false;
for(auto& statement : statements)
{
if(!statement.src2) continue;

bool src1cst = statement.src1.get()->GetSymbol().get()->IsConstant();
bool src2cst = statement.src2.get()->GetSymbol().get()->IsConstant();

if(src1cst || src2cst || !statement.src1.get()->Equals(statement.src2.get())) continue;
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I'm not very good with logical expressions, so I just want to make sure I understand properly :)

This function transforms statements that have the same non-constant src1 and src2 operands?

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@Zer0xFF Zer0xFF Jun 10, 2020 •
edited
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yes, (checking if they're constant is easier then checking if they're !(rel || reg || tmp)).


switch(statement.op)
{
case OP_AND64:
case OP_MD_OR:
{
statement.op = OP_MOV;
statement.src2.reset();
changed = true;
}
break;
case OP_XOR:
{
statement.op = OP_MOV;
statement.src1 = MakeSymbolRef(MakeSymbol(SYM_CONSTANT, 0));
statement.src2.reset();
changed = true;
}
break;
case OP_FP_SUB:
{
float constant = 0;
statement.op = OP_FP_LDCST;
statement.src1 = MakeSymbolRef(MakeSymbol(SYM_CONSTANT, *reinterpret_cast<uint32*>(&constant)));
statement.src2.reset();
changed = true;
}
break;
case OP_CMP64:
case OP_FP_CMP:
{
SymbolPtr result;
switch(statement.jmpCondition)
{
case CONDITION_EQ:
case CONDITION_LE:
case CONDITION_GE:
result = MakeSymbol(SYM_CONSTANT, 1);
break;
default:
result = MakeSymbol(SYM_CONSTANT, 0);
break;

}
statement.op = OP_MOV;
statement.src1 = MakeSymbolRef(result);
statement.src2.reset();
changed = true;
}
break;
case OP_FP_DIV:
{
float constant = 1;
statement.op = OP_FP_LDCST;
statement.src1 = MakeSymbolRef(MakeSymbol(SYM_CONSTANT, *reinterpret_cast<uint32*>(&constant)));
statement.src2.reset();
changed = true;
};
break;
default:
break;
}
}
return changed;
}

bool CJitter::ConstantFolding(StatementList& statements)
{
bool changed = false;
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