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Merge pull request #9366 from ethereum/wasm-clz

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Fix yulInterpreter to correctly handle i32.clz
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Daniel Kirchner 2020-07-10 20:36:24 +02:00 committed by GitHub
commit 65ed93d99f
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1 changed files with 8 additions and 5 deletions
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13
test/tools/yulInterpreter/EwasmBuiltinInterpreter.cpp
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@ -51,8 +51,9 @@ void copyZeroExtended(
_target[_targetOffset + i] = _sourceOffset + i < _source.size() ? _source[_sourceOffset + i] : 0;
}
/// Count leading zeros for uint64
uint64_t clz(uint64_t _v)
/// Count leading zeros for uint64. Following WebAssembly rules, it returns 64 for @a _v being zero.
/// NOTE: the clz builtin of the compiler may or may not do this
uint64_t clz64(uint64_t _v)
{
if (_v == 0)
return 64;
@ -133,7 +134,11 @@ u256 EwasmBuiltinInterpreter::evalBuiltin(YulString _fun, vector<u256> const& _a
accessMemory(arg[0], 4);
return readMemoryHalfWord(arg[0]);
}
else if (_fun == "i32.clz"_yulstring)
// NOTE: the clz implementation assumes 64-bit inputs, hence the adjustment
return clz64(arg[0] & uint32_t(-1)) - 32;
else if (_fun == "i64.clz"_yulstring)
return clz64(arg[0]);
string prefix = _fun.str();
string suffix;
@ -202,8 +207,6 @@ u256 EwasmBuiltinInterpreter::evalWasmBuiltin(string const& _fun, vector<Word> c
return arg[0] != arg[1] ? 1 : 0;
else if (_fun == "eqz")
return arg[0] == 0 ? 1 : 0;
else if (_fun == "clz")
return clz(arg[0]);
else if (_fun == "lt_u")
return arg[0] < arg[1] ? 1 : 0;
else if (_fun == "gt_u")