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| author | chriseth <c@ethdev.com> | 2016-09-16 18:56:52 +0800 |
|---|---|---|
| committer | chriseth <c@ethdev.com> | 2016-09-17 17:29:54 +0800 |
| commit | 5a45990458e9fc39a124d2b949ff77d1f6f1d8a7 (patch) | |
| tree | 9cb12e76c9c6c3a1beb79df1745986ade915f128 | |
| parent | dd2f878e594807cb86bdb49bc979c63e2b8d7e81 (diff) | |
| download | dexon-solidity-5a45990458e9fc39a124d2b949ff77d1f6f1d8a7.tar.gz dexon-solidity-5a45990458e9fc39a124d2b949ff77d1f6f1d8a7.tar.zst dexon-solidity-5a45990458e9fc39a124d2b949ff77d1f6f1d8a7.zip | |
Access output memory area so that we do not pay for resize during call.
| -rw-r--r-- | libsolidity/codegen/ExpressionCompiler.cpp | 17 | ||||
| -rw-r--r-- | test/libsolidity/SolidityEndToEndTest.cpp | 2 |
2 files changed, 14 insertions, 5 deletions
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp index 96ca4296..26acd8a4 100644 --- a/libsolidity/codegen/ExpressionCompiler.cpp +++ b/libsolidity/codegen/ExpressionCompiler.cpp @@ -1476,6 +1476,18 @@ void ExpressionCompiler::appendExternalFunctionCall( utils().storeFreeMemoryPointer(); } + // Touch the end of the output area so that we do not pay for memory resize during the call + // (which we would have to subtract from the gas left) + // We could also just use MLOAD; POP right before the gas calculation, but the optimizer + // would remove that, so we use MSTORE here. + if (!_functionType.gasSet() && retSize > 0) + { + m_context << u256(0); + utils().fetchFreeMemoryPointer(); + // This touches too much, but that way we save some rounding arithmetics + m_context << u256(retSize) << Instruction::ADD << Instruction::MSTORE; + } + // Copy function identifier to memory. utils().fetchFreeMemoryPointer(); if (!_functionType.isBareCall() || manualFunctionId) @@ -1551,10 +1563,7 @@ void ExpressionCompiler::appendExternalFunctionCall( gasNeededByCaller += eth::GasCosts::callValueTransferGas; if (!isCallCode && !isDelegateCall && !existenceChecked) gasNeededByCaller += eth::GasCosts::callNewAccountGas; // we never know - m_context << - gasNeededByCaller << - Instruction::GAS << - Instruction::SUB; + m_context << gasNeededByCaller << Instruction::GAS << Instruction::SUB; } if (isDelegateCall) m_context << Instruction::DELEGATECALL; diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp index c8bc7ff9..0ce2851b 100644 --- a/test/libsolidity/SolidityEndToEndTest.cpp +++ b/test/libsolidity/SolidityEndToEndTest.cpp @@ -7191,7 +7191,7 @@ BOOST_AUTO_TEST_CASE(mem_resize_is_not_paid_at_call) // This tests that memory resize for return values is not paid during the call, which would // make the gas calculation overly complex. We access the end of the output area before // the call is made. - // Tests that this also survivecs the optimizer. + // Tests that this also survives the optimizer. char const* sourceCode = R"( contract C { function f() returns (uint[200]) {} |