♻️ More memory-safe annotations #1353
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
shuhuiluo
reviewed
Feb 11, 2025
| @@ -50,6 +51,7 @@ contract EIP7702Proxy { | |||
|
|
|||
| fallback() external payable virtual { | |||
| uint256 s = __self; | |||
| /// @solidity memory-safe-assembly | |||
| assembly { | |||
| mstore(0x40, returndatasize()) // Optimization trick to change `6040608052` into `3d604052`. | |||
There was a problem hiding this comment.
Do you mean 6080604052 (mstore(0x40, 0x80))?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
https://docs.soliditylang.org/en/latest/assembly.html#advanced-safe-use-of-memory
Beyond the strict definition of memory-safety given above, there are cases in which you may want to use more than 64 bytes of scratch space starting at memory offset 0. If you are careful, it can be admissible to use memory up to (and not including) offset 0x80 and still safely declare the assembly block as memory-safe. This is admissible under either of the following conditions:
By the end of the assembly block, the free memory pointer at offset 0x40 is restored to a sane value (i.e. it is either restored to its original value or an increment of it due to a manual memory allocation), and the memory word at offset 0x60 is restored to a value of zero.
The assembly block terminates, i.e. execution can never return to high-level Solidity code. This is the case, for example, if your assembly block unconditionally ends in calling the revert opcode.
Checklist
Ensure you completed all of the steps below before submitting your pull request:
forge fmt?forge test?Pull requests with an incomplete checklist will be thrown out.