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Simplify and add comments for memory regions operations
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@0xVolosnikov
0xVolosnikov committed Jan 2, 2025
1 parent 20f37ff commit e24895c
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Showing 2 changed files with 105 additions and 84 deletions.
126 changes: 70 additions & 56 deletions system-contracts/contracts/EvmEmulator.yul
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1234,45 +1234,52 @@ object "EvmEmulator" {
}

////////////////////////////////////////////////////////////////
// EXTCODECOPY FUNCTIONALITY
// MEMORY REGIONS FUNCTIONALITY
////////////////////////////////////////////////////////////////

function $llvm_AlwaysInline_llvm$_copyRest(dest, val, len) {
let rest_bits := shl(3, len)
let upper_bits := sub(256, rest_bits)
let val_mask := shl(upper_bits, MAX_UINT())
let val_masked := and(val, val_mask)
let dst_val := mload(dest)
let dst_mask := shr(rest_bits, MAX_UINT())
let dst_masked := and(dst_val, dst_mask)
mstore(dest, or(val_masked, dst_masked))
}

// Copy the region of memory
function $llvm_AlwaysInline_llvm$_memcpy(dest, src, len) {
let dest_addr := dest
let src_addr := src
let dest_end := add(dest, and(len, sub(0, 32)))
for { } lt(dest_addr, dest_end) {} {
mstore(dest_addr, mload(src_addr))
dest_addr := add(dest_addr, 32)
src_addr := add(src_addr, 32)
// Copy all the whole memory words in a cycle
let destIndex := dest
let srcIndex := src
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for { } lt(destIndex, destEndIndex) {} {
mstore(destIndex, mload(srcIndex))
destIndex := add(destIndex, 32)
srcIndex := add(srcIndex, 32)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_addr, mload(src_addr), rest_len)
// Copy the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destIndex, mload(srcIndex), remainderLen)
}
}

function $llvm_AlwaysInline_llvm$_memsetToZero(dest,len) {
let dest_end := add(dest, and(len, sub(0, 32)))
for {let i := dest} lt(i, dest_end) { i := add(i, 32) } {
// Write the last part of the copied/cleaned memory region (smaller than the memory word)
function $llvm_AlwaysInline_llvm$_memWriteRemainder(dest, remainder, len) {
let remainderBitLength := shl(3, len) // bytes to bits

let existingValue := mload(dest)
let existingValueMask := shr(remainderBitLength, MAX_UINT())
let existingValueMasked := and(existingValue, existingValueMask) // clean up place for remainder

let remainderMasked := and(remainder, not(existingValueMask)) // using only `len` higher bytes of remainder word
mstore(dest, or(remainderMasked, existingValueMasked))
}

// Clean the region of memory
function $llvm_AlwaysInline_llvm$_memsetToZero(dest, len) {
// Clean all the whole memory words in a cycle
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for {let i := dest} lt(i, destEndIndex) { i := add(i, 32) } {
mstore(i, 0)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_end, 0, rest_len)
// Clean the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destEndIndex, 0, remainderLen)
}
}

Expand Down Expand Up @@ -4154,45 +4161,52 @@ object "EvmEmulator" {
}

////////////////////////////////////////////////////////////////
// EXTCODECOPY FUNCTIONALITY
// MEMORY REGIONS FUNCTIONALITY
////////////////////////////////////////////////////////////////

function $llvm_AlwaysInline_llvm$_copyRest(dest, val, len) {
let rest_bits := shl(3, len)
let upper_bits := sub(256, rest_bits)
let val_mask := shl(upper_bits, MAX_UINT())
let val_masked := and(val, val_mask)
let dst_val := mload(dest)
let dst_mask := shr(rest_bits, MAX_UINT())
let dst_masked := and(dst_val, dst_mask)
mstore(dest, or(val_masked, dst_masked))
}

// Copy the region of memory
function $llvm_AlwaysInline_llvm$_memcpy(dest, src, len) {
let dest_addr := dest
let src_addr := src
let dest_end := add(dest, and(len, sub(0, 32)))
for { } lt(dest_addr, dest_end) {} {
mstore(dest_addr, mload(src_addr))
dest_addr := add(dest_addr, 32)
src_addr := add(src_addr, 32)
// Copy all the whole memory words in a cycle
let destIndex := dest
let srcIndex := src
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for { } lt(destIndex, destEndIndex) {} {
mstore(destIndex, mload(srcIndex))
destIndex := add(destIndex, 32)
srcIndex := add(srcIndex, 32)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_addr, mload(src_addr), rest_len)
// Copy the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destIndex, mload(srcIndex), remainderLen)
}
}

function $llvm_AlwaysInline_llvm$_memsetToZero(dest,len) {
let dest_end := add(dest, and(len, sub(0, 32)))
for {let i := dest} lt(i, dest_end) { i := add(i, 32) } {
// Write the last part of the copied/cleaned memory region (smaller than the memory word)
function $llvm_AlwaysInline_llvm$_memWriteRemainder(dest, remainder, len) {
let remainderBitLength := shl(3, len) // bytes to bits

let existingValue := mload(dest)
let existingValueMask := shr(remainderBitLength, MAX_UINT())
let existingValueMasked := and(existingValue, existingValueMask) // clean up place for remainder

let remainderMasked := and(remainder, not(existingValueMask)) // using only `len` higher bytes of remainder word
mstore(dest, or(remainderMasked, existingValueMasked))
}

// Clean the region of memory
function $llvm_AlwaysInline_llvm$_memsetToZero(dest, len) {
// Clean all the whole memory words in a cycle
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for {let i := dest} lt(i, destEndIndex) { i := add(i, 32) } {
mstore(i, 0)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_end, 0, rest_len)
// Clean the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destEndIndex, 0, remainderLen)
}
}

Expand Down
63 changes: 35 additions & 28 deletions system-contracts/evm-emulator/EvmEmulatorFunctions.template.yul
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1174,45 +1174,52 @@ function _saveConstructorReturnGas() -> gasLeft, addr {
}

////////////////////////////////////////////////////////////////
// EXTCODECOPY FUNCTIONALITY
// MEMORY REGIONS FUNCTIONALITY
////////////////////////////////////////////////////////////////

function $llvm_AlwaysInline_llvm$_copyRest(dest, val, len) {
let rest_bits := shl(3, len)
let upper_bits := sub(256, rest_bits)
let val_mask := shl(upper_bits, MAX_UINT())
let val_masked := and(val, val_mask)
let dst_val := mload(dest)
let dst_mask := shr(rest_bits, MAX_UINT())
let dst_masked := and(dst_val, dst_mask)
mstore(dest, or(val_masked, dst_masked))
}

// Copy the region of memory
function $llvm_AlwaysInline_llvm$_memcpy(dest, src, len) {
let dest_addr := dest
let src_addr := src
let dest_end := add(dest, and(len, sub(0, 32)))
for { } lt(dest_addr, dest_end) {} {
mstore(dest_addr, mload(src_addr))
dest_addr := add(dest_addr, 32)
src_addr := add(src_addr, 32)
// Copy all the whole memory words in a cycle
let destIndex := dest
let srcIndex := src
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for { } lt(destIndex, destEndIndex) {} {
mstore(destIndex, mload(srcIndex))
destIndex := add(destIndex, 32)
srcIndex := add(srcIndex, 32)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_addr, mload(src_addr), rest_len)
// Copy the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destIndex, mload(srcIndex), remainderLen)
}
}

function $llvm_AlwaysInline_llvm$_memsetToZero(dest,len) {
let dest_end := add(dest, and(len, sub(0, 32)))
for {let i := dest} lt(i, dest_end) { i := add(i, 32) } {
// Write the last part of the copied/cleaned memory region (smaller than the memory word)
function $llvm_AlwaysInline_llvm$_memWriteRemainder(dest, remainder, len) {
let remainderBitLength := shl(3, len) // bytes to bits

let existingValue := mload(dest)
let existingValueMask := shr(remainderBitLength, MAX_UINT())
let existingValueMasked := and(existingValue, existingValueMask) // clean up place for remainder

let remainderMasked := and(remainder, not(existingValueMask)) // using only `len` higher bytes of remainder word
mstore(dest, or(remainderMasked, existingValueMasked))
}

// Clean the region of memory
function $llvm_AlwaysInline_llvm$_memsetToZero(dest, len) {
// Clean all the whole memory words in a cycle
let destEndIndex := add(dest, and(len, sub(0, 32))) // len / 32 words
for {let i := dest} lt(i, destEndIndex) { i := add(i, 32) } {
mstore(i, 0)
}

let rest_len := and(len, 31)
if rest_len {
$llvm_AlwaysInline_llvm$_copyRest(dest_end, 0, rest_len)
// Clean the remainder (if any)
let remainderLen := and(len, 31)
if remainderLen {
$llvm_AlwaysInline_llvm$_memWriteRemainder(destEndIndex, 0, remainderLen)
}
}

Expand Down

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