Variables are free with regards to code size.

This commit is contained in:
chriseth 2019-01-09 16:50:41 +01:00
parent 63319cfdcd
commit edda79eec5
3 changed files with 138 additions and 3 deletions

View File

@ -25,6 +25,9 @@
#include <libevmasm/Instruction.h>
#include <libdevcore/Visitor.h>
using namespace std;
using namespace dev;
using namespace yul;
@ -45,7 +48,7 @@ size_t CodeSize::codeSize(Expression const& _expression)
size_t CodeSize::codeSize(Block const& _block)
{
CodeSize cs;
cs(_block);
cs.visit(_block);
return cs.m_size;
}
@ -53,14 +56,21 @@ void CodeSize::visit(Statement const& _statement)
{
if (_statement.type() == typeid(FunctionDefinition))
return;
else if (!(
_statement.type() == typeid(Block) ||
_statement.type() == typeid(ExpressionStatement) ||
_statement.type() == typeid(Assignment) ||
_statement.type() == typeid(VariableDeclaration)
))
++m_size;
++m_size;
ASTWalker::visit(_statement);
}
void CodeSize::visit(Expression const& _expression)
{
++m_size;
if (_expression.type() != typeid(Identifier))
++m_size;
ASTWalker::visit(_expression);
}

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@ -30,6 +30,13 @@ namespace yul
* More specifically, the number of AST nodes.
* Ignores function definitions while traversing the AST.
* If you want to know the size of a function, you have to invoke this on its body.
*
* As an exception, the following AST elements have a cost of zero:
* - expression statement (only the expression inside has a cost)
* - block (only the statements inside have a cost)
* - variable references
* - variable declarations (only the right hand side has a cost)
* - assignments (only the value has a cost)
*/
class CodeSize: public ASTWalker
{
@ -39,6 +46,8 @@ public:
static size_t codeSize(Block const& _block);
private:
CodeSize() {}
void visit(Statement const& _statement) override;
void visit(Expression const& _expression) override;

116
test/libyul/Metrics.cpp Normal file
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@ -0,0 +1,116 @@
/*
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/>.
*/
/**
* Unit tests for the code metrics.
*/
#include <test/Options.h>
#include <test/libyul/Common.h>
#include <libyul/optimiser/Metrics.h>
#include <libyul/AsmData.h>
using namespace std;
using namespace langutil;
namespace yul
{
namespace test
{
namespace
{
size_t codeSize(string const& _source)
{
shared_ptr<Block> ast = parse(_source, false).first;
BOOST_REQUIRE(ast);
return CodeSize::codeSize(*ast);
}
}
BOOST_AUTO_TEST_SUITE(YulCodeSize)
BOOST_AUTO_TEST_CASE(empty_code)
{
BOOST_CHECK_EQUAL(codeSize("{}"), 0);
}
BOOST_AUTO_TEST_CASE(nested_blocks)
{
BOOST_CHECK_EQUAL(codeSize("{ {} {} {{ }} }"), 0);
}
BOOST_AUTO_TEST_CASE(instruction)
{
BOOST_CHECK_EQUAL(codeSize("{ pop(calldatasize()) }"), 2);
}
BOOST_AUTO_TEST_CASE(variables_are_free)
{
BOOST_CHECK_EQUAL(codeSize("{ let x let y let a, b, c }"), 0);
}
BOOST_AUTO_TEST_CASE(constants_cost_one)
{
BOOST_CHECK_EQUAL(codeSize("{ let x := 3 }"), 1);
}
BOOST_AUTO_TEST_CASE(functions_are_skipped)
{
BOOST_CHECK_EQUAL(codeSize("{ function f(x) -> r { r := mload(x) } }"), 0);
}
BOOST_AUTO_TEST_CASE(function_with_arguments)
{
BOOST_CHECK_EQUAL(codeSize("{ function f(x) { sstore(x, 2) } f(2) }"), 2);
}
BOOST_AUTO_TEST_CASE(function_with_variables_as_arguments)
{
BOOST_CHECK_EQUAL(codeSize("{ function f(x) { sstore(x, 2) } let y f(y) }"), 1);
}
BOOST_AUTO_TEST_CASE(function_with_variables_and_constants_as_arguments)
{
BOOST_CHECK_EQUAL(codeSize(
"{ function f(x, r) -> z { sstore(x, r) z := r } let y let t := f(y, 2) }"
), 2);
}
BOOST_AUTO_TEST_CASE(assignment)
{
BOOST_CHECK_EQUAL(codeSize("{ let a a := 3 }"), 1);
}
BOOST_AUTO_TEST_CASE(assignments_between_vars_are_free)
{
BOOST_CHECK_EQUAL(codeSize("{ let a let b := a a := b }"), 0);
}
BOOST_AUTO_TEST_CASE(assignment_complex)
{
BOOST_CHECK_EQUAL(codeSize("{ let a let x := mload(a) a := sload(x) }"), 2);
}
BOOST_AUTO_TEST_SUITE_END()
}
}