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Optimize obsolete ANDs in combination with certain SHIFTs

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This commit is contained in:
Mathias Baumann
2019-03-29 10:08:05 +01:00
parent 84fbf605aa
commit 5c66ccc179
3 changed files with 103 additions and 0 deletions
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test/libevmasm/Optimiser.cpp
+78
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@@ -1180,6 +1180,84 @@ BOOST_AUTO_TEST_CASE(cse_sub_zero)
});
}
BOOST_AUTO_TEST_CASE(cse_remove_redundant_shift_masking)
{
if (!dev::test::Options::get().evmVersion().hasBitwiseShifting())
return;
for (int i = 1; i < 256; i++)
{
checkCSE({
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::CALLVALUE,
u256(256-i),
Instruction::SHR,
Instruction::AND
}, {
Instruction::CALLVALUE,
u256(256-i),
Instruction::SHR,
});
checkCSE({
Instruction::CALLVALUE,
u256(256-i),
Instruction::SHR,
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::AND
}, {
Instruction::CALLVALUE,
u256(256-i),
Instruction::SHR,
});
}
// Check that opt. does NOT trigger
for (int i = 1; i < 255; i++)
{
checkCSE({
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::CALLVALUE,
u256(255-i),
Instruction::SHR,
Instruction::AND
}, { // Opt. did some reordering
Instruction::CALLVALUE,
u256(255-i),
Instruction::SHR,
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::AND
});
checkCSE({
Instruction::CALLVALUE,
u256(255-i),
Instruction::SHR,
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::AND
}, { // Opt. did some reordering
u256(boost::multiprecision::pow(u256(2), i)-1),
Instruction::CALLVALUE,
u256(255-i),
Instruction::SHR,
Instruction::AND
});
}
//(x >> (31*8)) & 0xffffffff
checkCSE({
Instruction::CALLVALUE,
u256(31*8),
Instruction::SHR,
u256(0xffffffff),
Instruction::AND
}, {
Instruction::CALLVALUE,
u256(31*8),
Instruction::SHR
});
}
BOOST_AUTO_TEST_CASE(cse_remove_unwanted_masking_of_address)
{
vector<Instruction> ops{