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-rw-r--r--Changelog.md1
-rw-r--r--libevmasm/Assembly.cpp2
-rw-r--r--libevmasm/PeepholeOptimiser.cpp11
-rw-r--r--test/libevmasm/Optimiser.cpp14
4 files changed, 25 insertions, 3 deletions
diff --git a/Changelog.md b/Changelog.md
index d78dbbba..22b5c002 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -13,6 +13,7 @@ Features:
* Type Checker: Require ``storage`` or ``memory`` keyword for local variables as experimental 0.5.0 feature.
Bugfixes:
+ * Optimizer: Remove unused stack computation results.
* Parser: Fix source location of VariableDeclarationStatement.
* Type Checker: Properly check array length and don't rely on an assertion in code generation.
* Type Checker: Properly support overwriting members inherited from ``address`` in a contract
diff --git a/libevmasm/Assembly.cpp b/libevmasm/Assembly.cpp
index df691e7d..37c4fb22 100644
--- a/libevmasm/Assembly.cpp
+++ b/libevmasm/Assembly.cpp
@@ -407,7 +407,7 @@ map<u256, u256> Assembly::optimiseInternal(
if (_settings.runPeephole)
{
PeepholeOptimiser peepOpt(m_items);
- while (peepOpt.optimise())
+ while (peepOpt.optimise() && count < 0xffffff)
count++;
}
diff --git a/libevmasm/PeepholeOptimiser.cpp b/libevmasm/PeepholeOptimiser.cpp
index 31fdd317..168d1109 100644
--- a/libevmasm/PeepholeOptimiser.cpp
+++ b/libevmasm/PeepholeOptimiser.cpp
@@ -249,6 +249,11 @@ void applyMethods(OptimiserState& _state, Method, OtherMethods... _other)
applyMethods(_state, _other...);
}
+size_t numberOfPops(AssemblyItems const& _items)
+{
+ return std::count(_items.begin(), _items.end(), Instruction::POP);
+}
+
}
bool PeepholeOptimiser::optimise()
@@ -257,8 +262,10 @@ bool PeepholeOptimiser::optimise()
while (state.i < m_items.size())
applyMethods(state, PushPop(), OpPop(), DoublePush(), DoubleSwap(), 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)
+ m_optimisedItems.size() == m_items.size() && (
+ eth::bytesRequired(m_optimisedItems, 3) < eth::bytesRequired(m_items, 3) ||
+ numberOfPops(m_optimisedItems) > numberOfPops(m_items)
+ )
))
{
m_items = std::move(m_optimisedItems);
diff --git a/test/libevmasm/Optimiser.cpp b/test/libevmasm/Optimiser.cpp
index 9dc49581..0ab95b08 100644
--- a/test/libevmasm/Optimiser.cpp
+++ b/test/libevmasm/Optimiser.cpp
@@ -841,6 +841,20 @@ BOOST_AUTO_TEST_CASE(peephole_double_push)
);
}
+BOOST_AUTO_TEST_CASE(peephole_pop_calldatasize)
+{
+ AssemblyItems items{
+ u256(4),
+ Instruction::CALLDATASIZE,
+ Instruction::LT,
+ Instruction::POP
+ };
+ PeepholeOptimiser peepOpt(items);
+ for (size_t i = 0; i < 3; i++)
+ BOOST_CHECK(peepOpt.optimise());
+ BOOST_CHECK(items.empty());
+}
+
BOOST_AUTO_TEST_CASE(jumpdest_removal)
{
AssemblyItems items{