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Merge pull request #2481 from ethereum/mload-optim

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MLOAD has side-effects, treat it like that in the optimiser
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chriseth 2017-07-01 17:53:01 +02:00 committed by GitHub
commit dd9416be29
3 changed files with 3 additions and 54 deletions
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2
Changelog.md
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@ -20,6 +20,7 @@ Features:
* Static Analyzer: Warn about deprecation of ``callcode``.
Bugfixes:
* Assembly: mark ``MLOAD`` to have side effects in the optimiser.
* Code generator: Use ``REVERT`` instead of ``INVALID`` for generated input validation routines.
* Type Checker: Fix address literals not being treated as compile-time constants.
* Type Checker: Disallow invoking the same modifier multiple times.
@ -33,6 +34,7 @@ Bugfixes:
* Code Generator: Fix negative stack size checks.
* Inline Assembly: Enforce function arguments when parsing functional instructions.
* Fixed segfault with constant function parameters
* Optimizer: Disallow optimizations involving ``MLOAD`` because it changes ``MSIZE``.
### 0.4.11 (2017-05-03)

2
libevmasm/Instruction.cpp
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@ -216,7 +216,7 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
{ Instruction::DIFFICULTY, { "DIFFICULTY", 0, 0, 1, false, Tier::Base } },
{ Instruction::GASLIMIT, { "GASLIMIT", 0, 0, 1, false, Tier::Base } },
{ Instruction::POP, { "POP", 0, 1, 0, false, Tier::Base } },
{ Instruction::MLOAD, { "MLOAD", 0, 1, 1, false, Tier::VeryLow } },
{ Instruction::MLOAD, { "MLOAD", 0, 1, 1, true, Tier::VeryLow } },
{ Instruction::MSTORE, { "MSTORE", 0, 2, 0, true, Tier::VeryLow } },
{ Instruction::MSTORE8, { "MSTORE8", 0, 2, 0, true, Tier::VeryLow } },
{ Instruction::SLOAD, { "SLOAD", 0, 1, 1, false, Tier::Special } },

53
test/libsolidity/SolidityOptimizer.cpp
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@ -697,59 +697,6 @@ BOOST_AUTO_TEST_CASE(cse_interleaved_storage_at_known_location_offset)
});
}
BOOST_AUTO_TEST_CASE(cse_interleaved_memory_at_known_location_offset)
{
// stores and reads to/from two locations which are known to be different,
// should not optimize away the first store, because the location overlaps with the load,
// but it should optimize away the second, because we know that the location is different by 32
AssemblyItems input{
u256(0x50),
Instruction::DUP2,
u256(2),
Instruction::ADD,
Instruction::MSTORE, // ["DUP1"+2] = 0x50
u256(0x60),
Instruction::DUP2,
u256(32),
Instruction::ADD,
Instruction::MSTORE, // ["DUP1"+32] = 0x60
Instruction::DUP1,
Instruction::MLOAD, // read from "DUP1"
u256(0x70),
Instruction::DUP3,
u256(32),
Instruction::ADD,
Instruction::MSTORE, // ["DUP1"+32] = 0x70
u256(0x80),
Instruction::DUP3,
u256(2),
Instruction::ADD,
Instruction::MSTORE, // ["DUP1"+2] = 0x80
};
// If the actual code changes too much, we could also simply check that the output contains
// exactly 3 MSTORE and exactly 1 MLOAD instruction.
checkCSE(input, {
u256(0x50),
u256(2),
Instruction::DUP3,
Instruction::ADD,
Instruction::SWAP1,
Instruction::DUP2,
Instruction::MSTORE, // ["DUP1"+2] = 0x50
Instruction::DUP2,
Instruction::MLOAD, // read from "DUP1"
u256(0x70),
u256(32),
Instruction::DUP5,
Instruction::ADD,
Instruction::MSTORE, // ["DUP1"+32] = 0x70
u256(0x80),
Instruction::SWAP1,
Instruction::SWAP2,
Instruction::MSTORE // ["DUP1"+2] = 0x80
});
}
BOOST_AUTO_TEST_CASE(cse_deep_stack)
{
AssemblyItems input{