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| author | Daniel Kirchner <daniel@ekpyron.org> | 2018-06-12 23:19:20 +0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2018-06-12 23:19:20 +0800 |
| commit | e2f4a9fcf409df1108d355824de12ff43682a728 (patch) | |
| tree | 0e1be338e5347370ebca2075b164b56bc61046dd | |
| parent | 2c8eca5dcfc5f961615eb1673f150d3088954a46 (diff) | |
| parent | 510f227bd78cda33181531141c88c6b948d72935 (diff) | |
| download | dexon-solidity-e2f4a9fcf409df1108d355824de12ff43682a728.tar.gz dexon-solidity-e2f4a9fcf409df1108d355824de12ff43682a728.tar.zst dexon-solidity-e2f4a9fcf409df1108d355824de12ff43682a728.zip | |
Merge pull request #4277 from ethereum/signedRightShift
Signed Right Shift: Additional test and more explanation.
| -rw-r--r-- | libsolidity/ast/Types.cpp | 9 | ||||
| -rw-r--r-- | test/libsolidity/SolidityEndToEndTest.cpp | 33 |
2 files changed, 40 insertions, 2 deletions
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp index 94e04b6a..c4d97c64 100644 --- a/libsolidity/ast/Types.cpp +++ b/libsolidity/ast/Types.cpp @@ -1088,8 +1088,13 @@ TypePointer RationalNumberType::binaryOperatorResult(Token::Value _operator, Typ else { if (m_value.numerator() < 0) - // add 1 to the negative value before dividing to get a result that is strictly too large - // subtract 1 afterwards to round towards negative infinity + // Add 1 to the negative value before dividing to get a result that is strictly too large, + // then subtract 1 afterwards to round towards negative infinity. + // This is the same algorithm as used in ExpressionCompiler::appendShiftOperatorCode(...). + // To see this note that for negative x, xor(x,all_ones) = (-x-1) and + // therefore xor(div(xor(x,all_ones), exp(2, shift_amount)), all_ones) is + // -(-x - 1) / 2^shift_amount - 1, which is the same as + // (x + 1) / 2^shift_amount - 1. value = rational((m_value.numerator() + 1) / boost::multiprecision::pow(bigint(2), exponent) - bigint(1), 1); else value = rational(m_value.numerator() / boost::multiprecision::pow(bigint(2), exponent), 1); diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp index 3b3cc4f7..a4c02888 100644 --- a/test/libsolidity/SolidityEndToEndTest.cpp +++ b/test/libsolidity/SolidityEndToEndTest.cpp @@ -10508,6 +10508,39 @@ BOOST_AUTO_TEST_CASE(shift_right_garbled) ABI_CHECK(callContractFunction("f(uint8,uint8)", u256(0x0), u256(0x1004)), encodeArgs(u256(0xf))); } +BOOST_AUTO_TEST_CASE(shift_right_garbled_signed) +{ + char const* sourceCode = R"( + contract C { + function f(int8 a, uint8 b) returns (int) { + assembly { + a := 0xfffffff0 + } + // Higher bits should be signextended before the shift + return a >> b; + } + function g(int8 a, uint8 b) returns (int) { + assembly { + a := 0xf0 + } + // Higher bits should be signextended before the shift + return a >> b; + } + } + )"; + compileAndRun(sourceCode, 0, "C"); + ABI_CHECK(callContractFunction("f(int8,uint8)", u256(0x0), u256(3)), encodeArgs(u256(-2))); + ABI_CHECK(callContractFunction("f(int8,uint8)", u256(0x0), u256(4)), encodeArgs(u256(-1))); + ABI_CHECK(callContractFunction("f(int8,uint8)", u256(0x0), u256(0xFF)), encodeArgs(u256(-1))); + ABI_CHECK(callContractFunction("f(int8,uint8)", u256(0x0), u256(0x1003)), encodeArgs(u256(-2))); + ABI_CHECK(callContractFunction("f(int8,uint8)", u256(0x0), u256(0x1004)), encodeArgs(u256(-1))); + ABI_CHECK(callContractFunction("g(int8,uint8)", u256(0x0), u256(3)), encodeArgs(u256(-2))); + ABI_CHECK(callContractFunction("g(int8,uint8)", u256(0x0), u256(4)), encodeArgs(u256(-1))); + ABI_CHECK(callContractFunction("g(int8,uint8)", u256(0x0), u256(0xFF)), encodeArgs(u256(-1))); + ABI_CHECK(callContractFunction("g(int8,uint8)", u256(0x0), u256(0x1003)), encodeArgs(u256(-2))); + ABI_CHECK(callContractFunction("g(int8,uint8)", u256(0x0), u256(0x1004)), encodeArgs(u256(-1))); +} + BOOST_AUTO_TEST_CASE(shift_right_uint32) { char const* sourceCode = R"( |