crypto: Use exact size for x1 in modexp_even CRT#1465
Merged
Conversation
chfast
force-pushed
the
crypto/modexp_result_size
branch
from
120143f to
aa0fb5a
Compare
There was a problem hiding this comment.
Pull request overview
This PR reduces temporary storage in the even-modulus CRT path of the expmod precompile by sizing the x1 (odd-part result) buffer to the odd modulus size and updating internal word-wise add/sub helpers to support unequal operand lengths needed by this optimization.
Changes:
- Allow
add()/sub()helpers inmodexp.cppto acceptx.size() >= y.size()and propagate carry/borrow through remaining high words ofx. - Shrink
modexp_even()temporaryx1buffer fromr.size()words tomod_odd.size()words and adjust subtraction accordingly. - Add a unit test vector covering an even modulus with 1-word odd part and multi-word
2^kfactor to exercise carry/borrow propagation.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
lib/evmone_precompiles/modexp.cpp |
Reduces temp allocation in modexp_even() and updates add/sub helpers to handle shorter RHS operands with correct carry/borrow propagation. |
test/unittests/precompiles_expmod_test.cpp |
Adds a regression test vector targeting the shortened-operand add/sub behavior in the even-modulus CRT path. |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #1465 +/- ##
==========================================
+ Coverage 96.82% 97.85% +1.03%
==========================================
Files 152 152
Lines 14050 14057 +7
Branches 3246 3248 +2
==========================================
+ Hits 13604 13756 +152
+ Misses 306 160 -146
- Partials 140 141 +1
Flags with carried forward coverage won't be shown. Click here to find out more.
🚀 New features to boost your workflow:
|
chfast
force-pushed
the
crypto/modexp_result_size
branch
from
aa0fb5a to
8d49138
Compare
Shrink the x1 (odd-part result) buffer from r.size() to mod_odd.size() words, reducing temporary storage. Relax add/sub to handle shorter y operand with carry/borrow propagation through remaining high words.
chfast
force-pushed
the
crypto/modexp_result_size
branch
from
8d49138 to
c6033d1
Compare
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
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.
Shrink the x1 (odd-part result) buffer from r.size() to mod_odd.size() words, reducing temporary storage. Relax add/sub to handle shorter y operand with carry/borrow propagation through remaining high words.