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Do not rematerialize in loops.

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This commit is contained in:
chriseth 2019-11-29 12:04:29 +01:00
parent 25d3f27c11
commit 40c0602b5c
10 changed files with 45 additions and 30 deletions
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2
libyul/optimiser/Rematerialiser.cpp
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@ -81,7 +81,7 @@ void Rematerialiser::visit(Expression& _e)
if (
(refs <= 1 && m_variableLoopDepth.at(name) == m_loopDepth) ||
cost == 0 ||
(refs <= 5 && cost <= 1) ||
(refs <= 5 && cost <= 1 && m_loopDepth == 0) ||
m_varsToAlwaysRematerialize.count(name)
)
{

2
libyul/optimiser/Rematerialiser.h
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@ -33,7 +33,7 @@ namespace solidity::yul
* - the variable is referenced exactly once (and definition-to-reference does not cross a loop boundary)
* - the value is extremely cheap ("cost" of zero like ``caller()``)
* - the variable is referenced at most 5 times and the value is rather cheap
* ("cost" of at most 1 like a constant up to 0xff)
* ("cost" of at most 1 like a constant up to 0xff) and we are not in a loop
*
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/

4
test/libsolidity/gasTests/abiv2_optimised.sol
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@ -17,9 +17,9 @@ contract C {
// optimize-yul: true
// ----
// creation:
// codeDepositCost: 605800
// codeDepositCost: 603000
// executionCost: 638
// totalCost: 606438
// totalCost: 603638
// external:
// a(): 1029
// b(uint256): 2084

36
test/libyul/yulOptimizerTests/fullSuite/abi_example1.yul
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@ -492,34 +492,37 @@
// }
// function abi_decode_t_array$_t_array$_t_uint256_$2_memory_$dyn_memory_ptr(offset, end) -> array
// {
// if iszero(slt(add(offset, 0x1f), end)) { revert(array, array) }
// let _1 := 0x1f
// if iszero(slt(add(offset, _1), end)) { revert(array, array) }
// let length := calldataload(offset)
// array := allocateMemory(array_allocation_size_t_array$_t_address_$dyn_memory(length))
// let dst := array
// mstore(array, length)
// let _1 := 0x20
// dst := add(array, _1)
// let src := add(offset, _1)
// if gt(add(add(offset, mul(length, 0x40)), _1), end) { revert(0, 0) }
// let _2 := 0x20
// dst := add(array, _2)
// let src := add(offset, _2)
// let _3 := 0x40
// if gt(add(add(offset, mul(length, _3)), _2), end) { revert(0, 0) }
// let i := 0
// for { } lt(i, length) { i := add(i, 1) }
// {
// if iszero(slt(add(src, 0x1f), end)) { revert(0, 0) }
// let dst_1 := allocateMemory(array_allocation_size_t_array$_t_uint256_$2_memory(0x2))
// if iszero(slt(add(src, _1), end)) { revert(0, 0) }
// let _4 := 0x2
// let dst_1 := allocateMemory(array_allocation_size_t_array$_t_uint256_$2_memory(_4))
// let dst_2 := dst_1
// let src_1 := src
// let _2 := add(src, 0x40)
// if gt(_2, end) { revert(0, 0) }
// let _5 := add(src, _3)
// if gt(_5, end) { revert(0, 0) }
// let i_1 := 0
// for { } lt(i_1, 0x2) { i_1 := add(i_1, 1) }
// for { } lt(i_1, _4) { i_1 := add(i_1, 1) }
// {
// mstore(dst_1, calldataload(src_1))
// dst_1 := add(dst_1, _1)
// src_1 := add(src_1, _1)
// dst_1 := add(dst_1, _2)
// src_1 := add(src_1, _2)
// }
// mstore(dst, dst_2)
// dst := add(dst, _1)
// src := _2
// dst := add(dst, _2)
// src := _5
// }
// }
// function abi_decode_t_array$_t_uint256_$dyn_memory_ptr(offset, end) -> array
@ -548,8 +551,9 @@
// for { } lt(i, 0x3) { i := add(i, 1) }
// {
// mstore(pos, and(mload(srcPtr), sub(shl(160, 1), 1)))
// srcPtr := add(srcPtr, 0x20)
// pos := add(pos, 0x20)
// let _1 := 0x20
// srcPtr := add(srcPtr, _1)
// pos := add(pos, _1)
// }
// }
// function allocateMemory(size) -> memPtr

3
test/libyul/yulOptimizerTests/fullSuite/aztec.yul
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@ -375,7 +375,8 @@
// let i := 0
// for { } lt(i, n) { i := add(i, 0x01) }
// {
// calldatacopy(add(0x300, mul(i, 0x80)), add(add(notes, mul(i, 0xc0)), 0x60), 0x80)
// let _1 := 0x80
// calldatacopy(add(0x300, mul(i, _1)), add(add(notes, mul(i, 0xc0)), 0x60), _1)
// }
// mstore(0, keccak256(0x300, mul(n, 0x80)))
// }

10
test/libyul/yulOptimizerTests/fullSuite/clear_after_if_continue.yul
View File

@ -13,7 +13,15 @@
// {
// let y := mload(0x20)
// let _1 := iszero(and(y, 8))
// for { } iszero(_1) { if y { revert(0, 0) } }
// for { }
// iszero(_1)
// {
// if y
// {
// let _2 := 0
// revert(_2, _2)
// }
// }
// {
// if y { continue }
// sstore(1, 0)

3
test/libyul/yulOptimizerTests/fullSuite/devcon_example.yul
View File

@ -25,7 +25,8 @@
// let i := sum
// for { } lt(i, length) { i := add(i, 1) }
// {
// sum := add(sum, calldataload(add(add(_1, mul(i, 0x20)), 0x20)))
// let _2 := 0x20
// sum := add(sum, calldataload(add(add(_1, mul(i, _2)), _2)))
// }
// sstore(0, sum)
// }

3
test/libyul/yulOptimizerTests/fullSuite/loopInvariantCodeMotion.yul
View File

@ -29,7 +29,8 @@
// let _2 := calldataload(7)
// for { } lt(i, length) { i := add(i, 1) }
// {
// sum := add(sum, add(calldataload(add(add(_1, mul(i, 0x20)), 0x20)), _2))
// let _3 := 0x20
// sum := add(sum, add(calldataload(add(add(_1, mul(i, _3)), _3)), _2))
// }
// sstore(0, sum)
// }

4
test/libyul/yulOptimizerTests/rematerialiser/some_refs_small_cost_loop.yul
View File

@ -12,6 +12,6 @@
// ----
// {
// let x := 0xff
// for { } lt(0xff, 0x100) { }
// { let y := add(0xff, 1) }
// for { } lt(x, 0x100) { }
// { let y := add(x, 1) }
// }

8
test/libyul/yulOptimizerTests/rematerialiser/some_refs_small_cost_nested_loop.yul
View File

@ -17,10 +17,10 @@
// ----
// {
// let x := 0xff
// for { } lt(0xff, 0x100) { }
// for { } lt(x, 0x100) { }
// {
// let y := add(0xff, 1)
// for { } lt(0xff, 0x200) { }
// { let z := mul(0xff, 2) }
// let y := add(x, 1)
// for { } lt(x, 0x200) { }
// { let z := mul(x, 2) }
// }
// }