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Optimize Math operations using branchless bool to uint translation. #4878

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Merged
Amxx merged 10 commits into from
Feb 7, 2024
Merged

Optimize Math operations using branchless bool to uint translation. #4878

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7f5b1b3
Make Math.log2 branchless
CodeSandwich Feb 5, 2024
7523995
add Math.boolToUint
Amxx Feb 6, 2024
45bbe87
branchless rounding
Amxx Feb 6, 2024
c8e9e3c
Make boolToUint clean the upper bits
CodeSandwich Feb 6, 2024
32b3d97
Make log2 more readable
CodeSandwich Feb 6, 2024
8417107
Update .changeset/nervous-pans-grow.md
Amxx Feb 6, 2024
3ae1b4a
Move `boolToUint` to `SafeCast`
ernestognw Feb 6, 2024
f8cb792
Update .changeset/nervous-pans-grow.md
ernestognw Feb 6, 2024
a371515
fix generation
Amxx Feb 6, 2024
b0ad358
Merge branch 'master' into optimize_log2
Amxx Feb 7, 2024
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Make log2 more readable
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@CodeSandwich
CodeSandwich committed Feb 6, 2024
commit 32b3d97859a7a36795d720fe91f8dbdbbdc2bb54
58 changes: 28 additions & 30 deletions contracts/utils/math/Math.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -389,38 +389,37 @@ library Math {
*/
function log2(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
uint256 isGt;
uint256 exp;
unchecked {
isGt = boolToUint(value > 0xffffffffffffffffffffffffffffffff);
value >>= isGt * 128;
result += isGt * 128;
exp = 128 * boolToUint(value > (1 << 128) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0xffffffffffffffff);
value >>= isGt * 64;
result += isGt * 64;
exp = 64 * boolToUint(value > (1 << 64) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0xffffffff);
value >>= isGt * 32;
result += isGt * 32;
exp = 32 * boolToUint(value > (1 << 32) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0xffff);
value >>= isGt * 16;
result += isGt * 16;
exp = 16 * boolToUint(value > (1 << 16) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0xff);
value >>= isGt * 8;
result += isGt * 8;
exp = 8 * boolToUint(value > (1 << 8) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0xf);
value >>= isGt * 4;
result += isGt * 4;
exp = 4 * boolToUint(value > (1 << 4) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0x3);
value >>= isGt * 2;
result += isGt * 2;
exp = 2 * boolToUint(value > (1 << 2) - 1);
value >>= exp;
result += exp;

isGt = boolToUint(value > 0x1);
result += isGt;
result += boolToUint(value > 1);
}
return result;
}
Expand Down Expand Up @@ -495,24 +494,23 @@ library Math {
uint256 result = 0;
uint256 isGt;
unchecked {
isGt = boolToUint(value > 0xffffffffffffffffffffffffffffffff);
isGt = boolToUint(value > (1 << 128) - 1);
value >>= isGt * 128;
result += isGt * 16;

isGt = boolToUint(value > 0xffffffffffffffff);
isGt = boolToUint(value > (1 << 64) - 1);
value >>= isGt * 64;
result += isGt * 8;

isGt = boolToUint(value > 0xffffffff);
isGt = boolToUint(value > (1 << 32) - 1);
value >>= isGt * 32;
result += isGt * 4;

isGt = boolToUint(value > 0xffff);
isGt = boolToUint(value > (1 << 16) - 1);
value >>= isGt * 16;
result += isGt * 2;

isGt = boolToUint(value > 0xff);
result += isGt;
result += boolToUint(value > (1 << 8) - 1);
}
return result;
}
Expand Down