Skip to content

Rewrite storeBytesFromMemory without assembly #513

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
axic wants to merge 5 commits into
base: main
Choose a base branch
from
Open

Rewrite storeBytesFromMemory without assembly #513

Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
ccf5862
Rewrite storeBytesFromMemory without assembly
axic Jun 25, 2026
40c9ae7
Simplify
axic Jun 25, 2026
9517fdf
Optimize out one addition
axic Jun 30, 2026
dfd0078
Optimize further
axic Jun 30, 2026
81b5bcc
Use new expression sugars
axic Aug 2, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
69 changes: 33 additions & 36 deletions std/std.solc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2331,41 +2331,38 @@ instance array(t):StorageCopy {
// Shamelessly stolen from function copy_byte_array_to_storage_from_t_bytes_memory_ptr_to_t_bytes_storage
// TODO: consider wrapping behaviour at end of storage
function storeBytesFromMemory(slot: word, src: word) -> () {
assembly {
let newLen := mload(src)
let newLen = mload(src);
// TODO: check old len, cleanup etc
let srcOffset := 32
switch gt(newLen, 31)
case 1 {
mstore(0,slot)
let dstPtr := keccak256(0,32)
let loopEnd := and(newLen, not(0x1f))
let i := 0
for { } lt(i, loopEnd) { i := add(i, 0x20) } {
sstore(dstPtr, mload(add(src, srcOffset)))
dstPtr := add(dstPtr, 1)
srcOffset := add(srcOffset, 32)
}
if lt(loopEnd, newLen) {
let lastValue := mload(add(src, srcOffset))
let lastLen := and(newLen, 0x1f)
let mask := not(shr(mul(8, lastLen), not(0)))
let nudata := and(lastValue, mask) // a Yul variable cannot be called "data". Go figure.
sstore(dstPtr, nudata)
}
sstore(slot, add(mul(newLen, 2), 1))
}
default {
let value := 0
if newLen {
value := mload(add(src, srcOffset))
}
let mask := not(shr(mul(8, newLen), not(0)))
let nudata := and(value, mask)
let used := or(nudata, mul(2, newLen))
sstore(slot,used)
}
}
src += 32; // Move to data.
match newLen > 31 {
| true =>
// Long byte array (out-of-place encoding)
let dstPtr = hash1(slot);
let loopEnd = newLen & ~0x1f;
let trailing = loopEnd < newLen;
loopEnd += src;
for (; src < loopEnd; src += 32, dstPtr += 1) {
sstore(dstPtr, mload(src));
}
if (trailing) {
let lastValue = mload(src);
let lastLen = newLen & 0x1f;
let mask = ~shr(8 * lastLen, ~0);
let data_ = lastValue & mask;
sstore(dstPtr, data_);
}
sstore(slot, (newLen * 2) + 1);
| false =>
// Short byte array (in-place encoding)
let value = 0;
if (newLen != 0) {
value = mload(src);
}
let mask = ~shr(8 * newLen, ~0);
let data_ = value & mask;
let used = data_ | (2 * newLen);
sstore(slot, used);
}
}


Expand All @@ -2382,13 +2379,13 @@ function loadBytesFromStorage(slot:word, memPtr:word) -> word {
pos += 32;
match outOfPlaceEncoding {
| false =>
// Short byte array
// Short byte array (in-place encoding)
mstore(pos, slotValue & ~0xff);
let empty = iszero(length);
let notzero = iszero(empty);
return pos + (notzero * 32);
| true =>
// Long byte array
// Long byte array (out-of-place encoding)
let dataPos = hash1(slot);
let i = 0;
for (; i < length; i += 32, dataPos += 1) {
Expand Down
Loading