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-rw-r--r--libevmasm/Assembly.cpp4
-rw-r--r--libevmasm/CommonSubexpressionEliminator.h8
-rw-r--r--libevmasm/Instruction.cpp2
-rw-r--r--libevmasm/PeepholeOptimiser.cpp47
-rw-r--r--libevmasm/RuleList.h10
-rw-r--r--libevmasm/SemanticInformation.cpp7
-rw-r--r--libevmasm/SemanticInformation.h3
7 files changed, 73 insertions, 8 deletions
diff --git a/libevmasm/Assembly.cpp b/libevmasm/Assembly.cpp
index bd4ebf59..b71bc80c 100644
--- a/libevmasm/Assembly.cpp
+++ b/libevmasm/Assembly.cpp
@@ -438,13 +438,15 @@ map<u256, u256> Assembly::optimiseInternal(
// function types that can be stored in storage.
AssemblyItems optimisedItems;
+ bool usesMSize = (find(m_items.begin(), m_items.end(), AssemblyItem(Instruction::MSIZE)) != m_items.end());
+
auto iter = m_items.begin();
while (iter != m_items.end())
{
KnownState emptyState;
CommonSubexpressionEliminator eliminator(emptyState);
auto orig = iter;
- iter = eliminator.feedItems(iter, m_items.end());
+ iter = eliminator.feedItems(iter, m_items.end(), usesMSize);
bool shouldReplace = false;
AssemblyItems optimisedChunk;
try
diff --git a/libevmasm/CommonSubexpressionEliminator.h b/libevmasm/CommonSubexpressionEliminator.h
index 0b957a0e..b20de246 100644
--- a/libevmasm/CommonSubexpressionEliminator.h
+++ b/libevmasm/CommonSubexpressionEliminator.h
@@ -65,8 +65,9 @@ public:
/// Feeds AssemblyItems into the eliminator and @returns the iterator pointing at the first
/// item that must be fed into a new instance of the eliminator.
+ /// @param _msizeImportant if false, do not consider modification of MSIZE a side-effect
template <class _AssemblyItemIterator>
- _AssemblyItemIterator feedItems(_AssemblyItemIterator _iterator, _AssemblyItemIterator _end);
+ _AssemblyItemIterator feedItems(_AssemblyItemIterator _iterator, _AssemblyItemIterator _end, bool _msizeImportant);
/// @returns the resulting items after optimization.
AssemblyItems getOptimizedItems();
@@ -168,11 +169,12 @@ private:
template <class _AssemblyItemIterator>
_AssemblyItemIterator CommonSubexpressionEliminator::feedItems(
_AssemblyItemIterator _iterator,
- _AssemblyItemIterator _end
+ _AssemblyItemIterator _end,
+ bool _msizeImportant
)
{
assertThrow(!m_breakingItem, OptimizerException, "Invalid use of CommonSubexpressionEliminator.");
- for (; _iterator != _end && !SemanticInformation::breaksCSEAnalysisBlock(*_iterator); ++_iterator)
+ for (; _iterator != _end && !SemanticInformation::breaksCSEAnalysisBlock(*_iterator, _msizeImportant); ++_iterator)
feedItem(*_iterator);
if (_iterator != _end)
m_breakingItem = &(*_iterator++);
diff --git a/libevmasm/Instruction.cpp b/libevmasm/Instruction.cpp
index a677a631..f9bbad2c 100644
--- a/libevmasm/Instruction.cpp
+++ b/libevmasm/Instruction.cpp
@@ -199,7 +199,7 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
{ Instruction::ADDMOD, { "ADDMOD", 0, 3, 1, false, Tier::Mid } },
{ Instruction::MULMOD, { "MULMOD", 0, 3, 1, false, Tier::Mid } },
{ Instruction::SIGNEXTEND, { "SIGNEXTEND", 0, 2, 1, false, Tier::Low } },
- { Instruction::KECCAK256, { "KECCAK256", 0, 2, 1, false, Tier::Special } },
+ { Instruction::KECCAK256, { "KECCAK256", 0, 2, 1, true, Tier::Special } },
{ Instruction::ADDRESS, { "ADDRESS", 0, 0, 1, false, Tier::Base } },
{ Instruction::BALANCE, { "BALANCE", 0, 1, 1, false, Tier::Balance } },
{ Instruction::ORIGIN, { "ORIGIN", 0, 0, 1, false, Tier::Base } },
diff --git a/libevmasm/PeepholeOptimiser.cpp b/libevmasm/PeepholeOptimiser.cpp
index 168d1109..8a39de24 100644
--- a/libevmasm/PeepholeOptimiser.cpp
+++ b/libevmasm/PeepholeOptimiser.cpp
@@ -154,6 +154,51 @@ struct DoublePush: SimplePeepholeOptimizerMethod<DoublePush, 2>
}
};
+struct CommutativeSwap: SimplePeepholeOptimizerMethod<CommutativeSwap, 2>
+{
+ static bool applySimple(AssemblyItem const& _swap, AssemblyItem const& _op, std::back_insert_iterator<AssemblyItems> _out)
+ {
+ // Remove SWAP1 if following instruction is commutative
+ if (
+ _swap.type() == Operation &&
+ _swap.instruction() == Instruction::SWAP1 &&
+ SemanticInformation::isCommutativeOperation(_op)
+ )
+ {
+ *_out = _op;
+ return true;
+ }
+ else
+ return false;
+ }
+};
+
+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(
@@ -260,7 +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(), 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) ||
diff --git a/libevmasm/RuleList.h b/libevmasm/RuleList.h
index da522cec..abcf170c 100644
--- a/libevmasm/RuleList.h
+++ b/libevmasm/RuleList.h
@@ -89,6 +89,16 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleList(
u256 mask = (u256(1) << testBit) - 1;
return u256(boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask);
}, false},
+ {{Instruction::SHL, {A, B}}, [=]{
+ if (A.d() > 255)
+ return u256(0);
+ return u256(bigint(B.d()) << unsigned(A.d()));
+ }, false},
+ {{Instruction::SHR, {A, B}}, [=]{
+ if (A.d() > 255)
+ return u256(0);
+ return B.d() >> unsigned(A.d());
+ }, false},
// invariants involving known constants
{{Instruction::ADD, {X, 0}}, [=]{ return X; }, false},
diff --git a/libevmasm/SemanticInformation.cpp b/libevmasm/SemanticInformation.cpp
index 03870f7c..71267ee8 100644
--- a/libevmasm/SemanticInformation.cpp
+++ b/libevmasm/SemanticInformation.cpp
@@ -28,7 +28,7 @@ using namespace std;
using namespace dev;
using namespace dev::eth;
-bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item)
+bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item, bool _msizeImportant)
{
switch (_item.type())
{
@@ -59,6 +59,11 @@ bool SemanticInformation::breaksCSEAnalysisBlock(AssemblyItem const& _item)
return false;
if (_item.instruction() == Instruction::MSTORE)
return false;
+ if (!_msizeImportant && (
+ _item.instruction() == Instruction::MLOAD ||
+ _item.instruction() == Instruction::KECCAK256
+ ))
+ return false;
//@todo: We do not handle the following memory instructions for now:
// calldatacopy, codecopy, extcodecopy, mstore8,
// msize (note that msize also depends on memory read access)
diff --git a/libevmasm/SemanticInformation.h b/libevmasm/SemanticInformation.h
index 83656252..8bdc70be 100644
--- a/libevmasm/SemanticInformation.h
+++ b/libevmasm/SemanticInformation.h
@@ -38,7 +38,8 @@ class AssemblyItem;
struct SemanticInformation
{
/// @returns true if the given items starts a new block for common subexpression analysis.
- static bool breaksCSEAnalysisBlock(AssemblyItem const& _item);
+ /// @param _msizeImportant if false, consider an operation non-breaking if its only side-effect is that it modifies msize.
+ static bool breaksCSEAnalysisBlock(AssemblyItem const& _item, bool _msizeImportant);
/// @returns true if the item is a two-argument operation whose value does not depend on the
/// order of its arguments.
static bool isCommutativeOperation(AssemblyItem const& _item);
generated by cgit v1.2.3 (git 2.25.1) at 2025-04-27 03:19:36 +0800