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Merge pull request #2657 from ethereum/jumpdest-remover

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Introduce JumpdestRemover optimisation step
This commit is contained in:
Alex Beregszaszi 2017-08-25 11:20:56 +01:00 committed by GitHub
commit 38035f8e32
9 changed files with 243 additions and 22 deletions
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1
Changelog.md
View File

@ -1,6 +1,7 @@
### 0.4.17 (unreleased)
Features:
* Optimizer: Add new optimization step to remove unused ``JUMPDEST``s.
Bugfixes:

30
libevmasm/Assembly.cpp
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@ -24,6 +24,7 @@
#include <libevmasm/CommonSubexpressionEliminator.h>
#include <libevmasm/ControlFlowGraph.h>
#include <libevmasm/PeepholeOptimiser.h>
#include <libevmasm/JumpdestRemover.h>
#include <libevmasm/BlockDeduplicator.h>
#include <libevmasm/ConstantOptimiser.h>
#include <libevmasm/GasMeter.h>
@ -349,6 +350,7 @@ Assembly& Assembly::optimise(bool _enable, bool _isCreation, size_t _runs)
{
OptimiserSettings settings;
settings.isCreation = _isCreation;
settings.runJumpdestRemover = true;
settings.runPeephole = true;
if (_enable)
{
@ -357,18 +359,21 @@ Assembly& Assembly::optimise(bool _enable, bool _isCreation, size_t _runs)
settings.runConstantOptimiser = true;
}
settings.expectedExecutionsPerDeployment = _runs;
optimiseInternal(settings);
optimise(settings);
return *this;
}
Assembly& Assembly::optimise(OptimiserSettings _settings)
Assembly& Assembly::optimise(OptimiserSettings const& _settings)
{
optimiseInternal(_settings);
optimiseInternal(_settings, {});
return *this;
}
map<u256, u256> Assembly::optimiseInternal(OptimiserSettings _settings)
map<u256, u256> Assembly::optimiseInternal(
OptimiserSettings const& _settings,
std::set<size_t> const& _tagsReferencedFromOutside
)
{
// Run optimisation for sub-assemblies.
for (size_t subId = 0; subId < m_subs.size(); ++subId)
@ -376,7 +381,10 @@ map<u256, u256> Assembly::optimiseInternal(OptimiserSettings _settings)
OptimiserSettings settings = _settings;
// Disable creation mode for sub-assemblies.
settings.isCreation = false;
map<u256, u256> subTagReplacements = m_subs[subId]->optimiseInternal(settings);
map<u256, u256> subTagReplacements = m_subs[subId]->optimiseInternal(
settings,
JumpdestRemover::referencedTags(m_items, subId)
);
// Apply the replacements (can be empty).
BlockDeduplicator::applyTagReplacement(m_items, subTagReplacements, subId);
}
@ -387,6 +395,13 @@ map<u256, u256> Assembly::optimiseInternal(OptimiserSettings _settings)
{
count = 0;
if (_settings.runJumpdestRemover)
{
JumpdestRemover jumpdestOpt(m_items);
if (jumpdestOpt.optimise(_tagsReferencedFromOutside))
count++;
}
if (_settings.runPeephole)
{
PeepholeOptimiser peepOpt(m_items);
@ -473,8 +488,9 @@ LinkerObject const& Assembly::assemble() const
for (auto const& sub: m_subs)
{
sub->assemble();
if (!sub->m_tagPositionsInBytecode.empty())
subTagSize = max(subTagSize, *max_element(sub->m_tagPositionsInBytecode.begin(), sub->m_tagPositionsInBytecode.end()));
for (size_t tagPos: sub->m_tagPositionsInBytecode)
if (tagPos != size_t(-1) && tagPos > subTagSize)
subTagSize = tagPos;
}
LinkerObject& ret = m_assembledObject;

8
libevmasm/Assembly.h
View File

@ -100,6 +100,7 @@ public:
struct OptimiserSettings
{
bool isCreation = false;
bool runJumpdestRemover = false;
bool runPeephole = false;
bool runDeduplicate = false;
bool runCSE = false;
@ -110,7 +111,7 @@ public:
};
/// Execute optimisation passes as defined by @a _settings and return the optimised assembly.
Assembly& optimise(OptimiserSettings _settings);
Assembly& optimise(OptimiserSettings const& _settings);
/// Modify (if @a _enable is set) and return the current assembly such that creation and
/// execution gas usage is optimised. @a _isCreation should be true for the top-level assembly.
@ -128,8 +129,9 @@ public:
protected:
/// Does the same operations as @a optimise, but should only be applied to a sub and
/// returns the replaced tags.
std::map<u256, u256> optimiseInternal(OptimiserSettings _settings);
/// returns the replaced tags. Also takes an argument containing the tags of this assembly
/// that are referenced in a super-assembly.
std::map<u256, u256> optimiseInternal(OptimiserSettings const& _settings, std::set<size_t> const& _tagsReferencedFromOutside);
unsigned bytesRequired(unsigned subTagSize) const;

68
libevmasm/JumpdestRemover.cpp Normal file
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@ -0,0 +1,68 @@
/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Alex Beregszaszi
* Removes unused JUMPDESTs.
*/
#include "JumpdestRemover.h"
#include <libsolidity/interface/Exceptions.h>
#include <libevmasm/AssemblyItem.h>
using namespace std;
using namespace dev::eth;
using namespace dev;
bool JumpdestRemover::optimise(set<size_t> const& _tagsReferencedFromOutside)
{
set<size_t> references{referencedTags(m_items, -1)};
references.insert(_tagsReferencedFromOutside.begin(), _tagsReferencedFromOutside.end());
size_t initialSize = m_items.size();
/// Remove tags which are never referenced.
auto pend = remove_if(
m_items.begin(),
m_items.end(),
[&](AssemblyItem const& _item)
{
if (_item.type() != Tag)
return false;
auto asmIdAndTag = _item.splitForeignPushTag();
solAssert(asmIdAndTag.first == size_t(-1), "Sub-assembly tag used as label.");
size_t tag = asmIdAndTag.second;
return !references.count(tag);
}
);
m_items.erase(pend, m_items.end());
return m_items.size() != initialSize;
}
set<size_t> JumpdestRemover::referencedTags(AssemblyItems const& _items, size_t _subId)
{
set<size_t> ret;
for (auto const& item: _items)
if (item.type() == PushTag)
{
auto subAndTag = item.splitForeignPushTag();
if (subAndTag.first == _subId)
ret.insert(subAndTag.second);
}
return ret;
}

50
libevmasm/JumpdestRemover.h Normal file
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@ -0,0 +1,50 @@
/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Alex Beregszaszi
* Removes unused JUMPDESTs.
*/
#pragma once
#include <vector>
#include <cstddef>
#include <set>
namespace dev
{
namespace eth
{
class AssemblyItem;
using AssemblyItems = std::vector<AssemblyItem>;
class JumpdestRemover
{
public:
explicit JumpdestRemover(AssemblyItems& _items): m_items(_items) {}
bool optimise(std::set<size_t> const& _tagsReferencedFromOutside);
/// @returns a set of all tags from the given sub-assembly that are referenced
/// from the given list of items.
static std::set<size_t> referencedTags(AssemblyItems const& _items, size_t _subId);
private:
AssemblyItems& m_items;
};
}
}

84
test/libevmasm/Optimiser.cpp
View File

@ -22,6 +22,7 @@
#include <libevmasm/CommonSubexpressionEliminator.h>
#include <libevmasm/PeepholeOptimiser.h>
#include <libevmasm/JumpdestRemover.h>
#include <libevmasm/ControlFlowGraph.h>
#include <libevmasm/BlockDeduplicator.h>
#include <libevmasm/Assembly.h>
@ -840,6 +841,89 @@ BOOST_AUTO_TEST_CASE(peephole_double_push)
);
}
BOOST_AUTO_TEST_CASE(jumpdest_removal)
{
AssemblyItems items{
AssemblyItem(Tag, 2),
AssemblyItem(PushTag, 1),
u256(5),
AssemblyItem(Tag, 10),
AssemblyItem(Tag, 3),
u256(6),
AssemblyItem(Tag, 1),
Instruction::JUMP,
};
AssemblyItems expectation{
AssemblyItem(PushTag, 1),
u256(5),
u256(6),
AssemblyItem(Tag, 1),
Instruction::JUMP
};
JumpdestRemover jdr(items);
BOOST_REQUIRE(jdr.optimise({}));
BOOST_CHECK_EQUAL_COLLECTIONS(
items.begin(), items.end(),
expectation.begin(), expectation.end()
);
}
BOOST_AUTO_TEST_CASE(jumpdest_removal_subassemblies)
{
// This tests that tags from subassemblies are not removed
// if they are referenced by a super-assembly. Furthermore,
// tag unifications (due to block deduplication) is also
// visible at the super-assembly.
Assembly main;
AssemblyPointer sub = make_shared<Assembly>();
sub->append(u256(1));
auto t1 = sub->newTag();
sub->append(t1);
sub->append(u256(2));
sub->append(Instruction::JUMP);
auto t2 = sub->newTag();
sub->append(t2); // Identical to T1, will be unified
sub->append(u256(2));
sub->append(Instruction::JUMP);
auto t3 = sub->newTag();
sub->append(t3);
auto t4 = sub->newTag();
sub->append(t4);
auto t5 = sub->newTag();
sub->append(t5); // This will be removed
sub->append(u256(7));
sub->append(t4.pushTag());
sub->append(Instruction::JUMP);
size_t subId = size_t(main.appendSubroutine(sub).data());
main.append(t1.toSubAssemblyTag(subId));
main.append(t1.toSubAssemblyTag(subId));
main.append(u256(8));
main.optimise(true);
AssemblyItems expectationMain{
AssemblyItem(PushSubSize, 0),
t1.toSubAssemblyTag(subId).pushTag(),
t1.toSubAssemblyTag(subId).pushTag(),
u256(8)
};
BOOST_CHECK_EQUAL_COLLECTIONS(
main.items().begin(), main.items().end(),
expectationMain.begin(), expectationMain.end()
);
AssemblyItems expectationSub{
u256(1), t1.tag(), u256(2), Instruction::JUMP, t4.tag(), u256(7), t4.pushTag(), Instruction::JUMP
};
BOOST_CHECK_EQUAL_COLLECTIONS(
sub->items().begin(), sub->items().end(),
expectationSub.begin(), expectationSub.end()
);
}
BOOST_AUTO_TEST_CASE(cse_sub_zero)
{
checkCSE({

4
test/libsolidity/Assembly.cpp
View File

@ -119,11 +119,11 @@ BOOST_AUTO_TEST_CASE(location_test)
shared_ptr<string const> n = make_shared<string>("");
AssemblyItems items = compileContract(sourceCode);
vector<SourceLocation> locations =
vector<SourceLocation>(19, SourceLocation(2, 75, n)) +
vector<SourceLocation>(18, SourceLocation(2, 75, n)) +
vector<SourceLocation>(32, SourceLocation(20, 72, n)) +
vector<SourceLocation>{SourceLocation(42, 51, n), SourceLocation(65, 67, n)} +
vector<SourceLocation>(2, SourceLocation(58, 67, n)) +
vector<SourceLocation>(3, SourceLocation(20, 72, n));
vector<SourceLocation>(2, SourceLocation(20, 72, n));
checkAssemblyLocations(items, locations);
}

12
test/libsolidity/JSONCompiler.cpp
View File

@ -120,18 +120,18 @@ BOOST_AUTO_TEST_CASE(basic_compilation)
BOOST_CHECK(contract["bytecode"].isString());
BOOST_CHECK_EQUAL(
dev::test::bytecodeSansMetadata(contract["bytecode"].asString()),
"60606040523415600e57600080fd5b5b603680601c6000396000f30060606040525b600080fd00"
"60606040523415600e57600080fd5b603580601b6000396000f3006060604052600080fd00"
);
BOOST_CHECK(contract["runtimeBytecode"].isString());
BOOST_CHECK_EQUAL(
dev::test::bytecodeSansMetadata(contract["runtimeBytecode"].asString()),
"60606040525b600080fd00"
"6060604052600080fd00"
);
BOOST_CHECK(contract["functionHashes"].isObject());
BOOST_CHECK(contract["gasEstimates"].isObject());
BOOST_CHECK_EQUAL(
dev::jsonCompactPrint(contract["gasEstimates"]),
"{\"creation\":[62,10800],\"external\":{},\"internal\":{}}"
"{\"creation\":[61,10600],\"external\":{},\"internal\":{}}"
);
BOOST_CHECK(contract["metadata"].isString());
BOOST_CHECK(dev::test::isValidMetadata(contract["metadata"].asString()));
@ -162,18 +162,18 @@ BOOST_AUTO_TEST_CASE(single_compilation)
BOOST_CHECK(contract["bytecode"].isString());
BOOST_CHECK_EQUAL(
dev::test::bytecodeSansMetadata(contract["bytecode"].asString()),
"60606040523415600e57600080fd5b5b603680601c6000396000f30060606040525b600080fd00"
"60606040523415600e57600080fd5b603580601b6000396000f3006060604052600080fd00"
);
BOOST_CHECK(contract["runtimeBytecode"].isString());
BOOST_CHECK_EQUAL(
dev::test::bytecodeSansMetadata(contract["runtimeBytecode"].asString()),
"60606040525b600080fd00"
"6060604052600080fd00"
);
BOOST_CHECK(contract["functionHashes"].isObject());
BOOST_CHECK(contract["gasEstimates"].isObject());
BOOST_CHECK_EQUAL(
dev::jsonCompactPrint(contract["gasEstimates"]),
"{\"creation\":[62,10800],\"external\":{},\"internal\":{}}"
"{\"creation\":[61,10600],\"external\":{},\"internal\":{}}"
);
BOOST_CHECK(contract["metadata"].isString());
BOOST_CHECK(dev::test::isValidMetadata(contract["metadata"].asString()));

8
test/libsolidity/StandardCompiler.cpp
View File

@ -198,19 +198,19 @@ BOOST_AUTO_TEST_CASE(basic_compilation)
BOOST_CHECK(contract["evm"]["bytecode"]["object"].isString());
BOOST_CHECK_EQUAL(
dev::test::bytecodeSansMetadata(contract["evm"]["bytecode"]["object"].asString()),
"60606040523415600e57600080fd5b5b603680601c6000396000f30060606040525b600080fd00"
"60606040523415600e57600080fd5b603580601b6000396000f3006060604052600080fd00"
);
BOOST_CHECK(contract["evm"]["assembly"].isString());
BOOST_CHECK(contract["evm"]["assembly"].asString().find(
" /* \"fileA\":0:14 contract A { } */\n mstore(0x40, 0x60)\n jumpi(tag_1, iszero(callvalue))\n"
" 0x0\n dup1\n revert\ntag_1:\ntag_2:\n dataSize(sub_0)\n dup1\n dataOffset(sub_0)\n 0x0\n codecopy\n 0x0\n"
" 0x0\n dup1\n revert\ntag_1:\n dataSize(sub_0)\n dup1\n dataOffset(sub_0)\n 0x0\n codecopy\n 0x0\n"
" return\nstop\n\nsub_0: assembly {\n /* \"fileA\":0:14 contract A { } */\n"
" mstore(0x40, 0x60)\n tag_1:\n 0x0\n dup1\n revert\n\n"
" mstore(0x40, 0x60)\n 0x0\n dup1\n revert\n\n"
" auxdata: 0xa165627a7a7230582") == 0);
BOOST_CHECK(contract["evm"]["gasEstimates"].isObject());
BOOST_CHECK_EQUAL(
dev::jsonCompactPrint(contract["evm"]["gasEstimates"]),
"{\"creation\":{\"codeDepositCost\":\"10800\",\"executionCost\":\"62\",\"totalCost\":\"10862\"}}"
"{\"creation\":{\"codeDepositCost\":\"10600\",\"executionCost\":\"61\",\"totalCost\":\"10661\"}}"
);
BOOST_CHECK(contract["metadata"].isString());
BOOST_CHECK(dev::test::isValidMetadata(contract["metadata"].asString()));