Fix handling of 0x8000000 in compression #297
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
joshStillerman
added a commit
that referenced
this pull request
Jan 11, 2016
Fix handling of 0x8000000 in compression
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Outdated suggestions cannot be applied.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 fix should deal with what may be an old bug (http://marc.info/?l=gcc-bugs&m=130392514411475&w=2) in the gcc compiler with the logic handling the the 32-bit value of 0x80000000.
The code now tests for this 0x80000000 value and sets the bit width to 32 otherwise it uses the original logic.
This bug turned out to be much more subtle than previously thought. It only appeared when using certain versions of gcc and only when compiled with -O2 or higher. So attempting to debug the problem was difficult.