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Compute SHA3 additional gas cost in 64-bit precision

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Paweł Bylica 2015-01-12 16:41:00 +01:00
parent 3ebef61c5b
commit fdefaca410
1 changed files with 5 additions and 3 deletions
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8
libevmjit/GasMeter.cpp
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@ -173,10 +173,12 @@ void GasMeter::countSha3Data(llvm::Value* _dataLength)
assert(m_blockCost > 0); // SHA3 instruction is already counted assert(m_blockCost > 0); // SHA3 instruction is already counted
// TODO: This round ups to 32 happens in many places // TODO: This round ups to 32 happens in many places
// FIXME: Overflow possible but Memory::require() also called. Probably 64-bit arith can be used. // FIXME: 64-bit arith used, but not verified
static_assert(c_sha3WordGas != 1, "SHA3 data cost has changed. Update GasMeter"); static_assert(c_sha3WordGas != 1, "SHA3 data cost has changed. Update GasMeter");
auto words = m_builder.CreateUDiv(m_builder.CreateAdd(_dataLength, Constant::get(31)), Constant::get(32)); auto dataLength64 = getBuilder().CreateTrunc(_dataLength, Type::lowPrecision);
auto cost = m_builder.CreateNUWMul(Constant::get(c_sha3WordGas), words); auto words64 = m_builder.CreateUDiv(m_builder.CreateAdd(dataLength64, getBuilder().getInt64(31)), getBuilder().getInt64(32));
auto cost64 = m_builder.CreateNUWMul(getBuilder().getInt64(c_sha3WordGas), words64);
auto cost = getBuilder().CreateZExt(cost64, Type::Word);
count(cost); count(cost);
} }