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Optimizing mem gas cost

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This commit is contained in:
Tomasz Drwięga
2016-07-11 12:51:31 +02:00
parent edaf24a2ce
commit f1edd3d683
3 changed files with 79 additions and 10 deletions
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18
ethcore/src/evm/interpreter/gasometer.rs
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@@ -68,6 +68,9 @@ impl<Gas: CostType> Gasometer<Gas> {
let default_gas = Gas::from(schedule.tier_step_gas[tier]);
let cost = match instruction {
instructions::JUMPDEST => {
InstructionCost::Gas(Gas::from(1))
},
instructions::SSTORE => {
let address = H256::from(stack.peek(0));
let newval = stack.peek(1);
@@ -106,9 +109,6 @@ impl<Gas: CostType> Gasometer<Gas> {
instructions::EXTCODECOPY => {
InstructionCost::GasMemCopy(default_gas, try!(self.mem_needed(stack.peek(1), stack.peek(3))), try!(Gas::from_u256(*stack.peek(3))))
},
instructions::JUMPDEST => {
InstructionCost::Gas(Gas::from(1))
},
instructions::LOG0...instructions::LOG4 => {
let no_of_topics = instructions::get_log_topics(instruction);
let log_gas = schedule.log_gas + schedule.log_topic_gas * no_of_topics;
@@ -199,14 +199,12 @@ impl<Gas: CostType> Gasometer<Gas> {
let s = mem_size >> 5;
// s * memory_gas + s * s / quad_coeff_div
let a = overflowing!(s.overflow_mul(Gas::from(schedule.memory_gas)));
// We need to go to U512 to calculate s*s/quad_coeff_div
let b = U512::from(s.as_u256()) * U512::from(s.as_u256()) / U512::from(schedule.quad_coeff_div);
if b > U512::from(!U256::zero()) {
Err(evm::Error::OutOfGas)
} else {
Ok(overflowing!(a.overflow_add(try!(Gas::from_u256(U256::from(b))))))
}
// Calculate s*s/quad_coeff_div
let b = overflowing!(s.overflow_mul_div(s, Gas::from(schedule.quad_coeff_div)));
Ok(overflowing!(a.overflow_add(b)))
};
let current_mem_size = Gas::from(current_mem_size);
let req_mem_size_rounded = (overflowing!(mem_size.overflow_add(Gas::from(31 as usize))) >> 5) << 5;