[WIP] Tracking PR for LFI integrated rewriter (LLVM 20) #1
Conversation
This file contains hidden or 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
Adds the `aarch64_lfi`, `aarch64_lfi_stores` and `aarch64_lfi_jumps` subarches for AArch64. Reserves the necessary registers and disables compressed jump tables when targeting LFI.
This patch establishes the scaffolding for the LFI MC rewriter, based on the NaCl auto-sandboxing assembler. There is a generic MCLFIExpander, plus an AArch64-specific subclass where the rewriter will be implemented in a future patch.
When assembling a .s file using clang or llvm-mc, automatically run the LFI rewriter if targeting LFI.
Doesn't handle basic pre/post-indexed loads/stores yet.
There is a remaining corner case for certain instructions with hard-coded immediate offset values.
These directives make it possible to disable the LFI rewriter in GNU assembly.
Removes the aarch64_lfi_stores and aarch64_lfi_jumps target triples and replaces them with +lfi-stores and +lfi-jumps subtarget features for AArch64.
Also changes the instruction size estimate to include an additional guard instruction for loads/stores so that branch relaxation correctly resizes branches even before the expander is run.
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Outdated suggestions cannot be applied.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.
This PR is used for tracking the changes made for the LFI integrated rewriter applied to LLVM 20.1.7. The implementation is based on the NaCl auto-sandboxing assembler, adapted for AArch64 and LFI.