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Replace comparison operators with opposites if preceded by SWAP1

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This commit is contained in:
Alex Beregszaszi
2018-04-04 17:47:58 +02:00
parent efa0ccaf9e
commit 02ea0e547f
3 changed files with 66 additions and 6 deletions
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libevmasm/PeepholeOptimiser.cpp
+27 -1
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@@ -173,6 +173,32 @@ struct CommutativeSwap: SimplePeepholeOptimizerMethod<CommutativeSwap, 2>
}
};
struct SwapComparison: SimplePeepholeOptimizerMethod<SwapComparison, 2>
{
static bool applySimple(AssemblyItem const& _swap, AssemblyItem const& _op, std::back_insert_iterator<AssemblyItems> _out)
{
map<Instruction, Instruction> swappableOps{
{ Instruction::LT, Instruction::GT },
{ Instruction::GT, Instruction::LT },
{ Instruction::SLT, Instruction::SGT },
{ Instruction::SGT, Instruction::SLT }
};
if (
_swap.type() == Operation &&
_swap.instruction() == Instruction::SWAP1 &&
_op.type() == Operation &&
swappableOps.count(_op.instruction())
)
{
*_out = swappableOps.at(_op.instruction());
return true;
}
else
return false;
}
};
struct JumpToNext: SimplePeepholeOptimizerMethod<JumpToNext, 3>
{
static size_t applySimple(
@@ -279,7 +305,7 @@ bool PeepholeOptimiser::optimise()
{
OptimiserState state {m_items, 0, std::back_inserter(m_optimisedItems)};
while (state.i < m_items.size())
applyMethods(state, PushPop(), OpPop(), DoublePush(), DoubleSwap(), CommutativeSwap(), JumpToNext(), UnreachableCode(), TagConjunctions(), Identity());
applyMethods(state, PushPop(), OpPop(), DoublePush(), DoubleSwap(), CommutativeSwap(), SwapComparison(), JumpToNext(), UnreachableCode(), TagConjunctions(), Identity());
if (m_optimisedItems.size() < m_items.size() || (
m_optimisedItems.size() == m_items.size() && (
eth::bytesRequired(m_optimisedItems, 3) < eth::bytesRequired(m_items, 3) ||