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Merge pull request #1889 from chriseth/sol_multipleTagsOnStack

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Known state: store tags on stack as unions.
This commit is contained in:
chriseth 2015-05-15 11:12:13 +02:00
commit 779ce0131a
1 changed files with 43 additions and 0 deletions
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43
libsolidity/SolidityOptimizer.cpp
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@ -315,6 +315,49 @@ BOOST_AUTO_TEST_CASE(retain_information_in_branches)
BOOST_CHECK_EQUAL(1, numSHA3s);
}
BOOST_AUTO_TEST_CASE(store_tags_as_unions)
{
// This calls the same function from two sources and both calls have a certain sha3 on
// the stack at the same position.
// Without storing tags as unions, the return from the shared function would not know where to
// jump and thus all jumpdests are forced to clear their state and we do not know about the
// sha3 anymore.
// Note that, for now, this only works if the functions have the same number of return
// parameters since otherwise, the return jump addresses are at different stack positions
// which triggers the "unknown jump target" situation.
char const* sourceCode = R"(
contract test {
bytes32 data;
function f(uint x, bytes32 y) external returns (uint r_a, bytes32 r_d) {
r_d = sha3(y);
shared(y);
r_d = sha3(y);
r_a = 5;
}
function g(uint x, bytes32 y) external returns (uint r_a, bytes32 r_d) {
r_d = sha3(y);
shared(y);
r_d = bytes32(uint(sha3(y)) + 2);
r_a = 7;
}
function shared(bytes32 y) internal {
data = sha3(y);
}
}
)";
compileBothVersions(sourceCode);
compareVersions("f()", 7, "abc");
m_optimize = true;
bytes optimizedBytecode = compileAndRun(sourceCode, 0, "test");
size_t numSHA3s = 0;
eth::eachInstruction(optimizedBytecode, [&](Instruction _instr, u256 const&) {
if (_instr == eth::Instruction::SHA3)
numSHA3s++;
});
BOOST_CHECK_EQUAL(2, numSHA3s);
}
BOOST_AUTO_TEST_CASE(cse_intermediate_swap)
{
eth::KnownState state;