Fix Get Valid Counts when the number of boxes is zero #7229
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Outdated suggestions cannot be applied.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.
Thanks @trevor-m and @anijain2305 for finding this issue. Sometimes a model may propose 0 boxes, and the code had a place that ended up assigning uninitialized memory to valid_counts, which could cause memory access issues in NMS.
The diff is kind of ugly, but this PR simply wraps the exclusive scan in this:
Which runs the algorithm if there are boxes to check, and otherwise assigns valid_count to 0.
Unfortunately, since the issue is randomly uninitialized memory getting assigned to valid_count, I haven't been able to write a unit test that consistently fails with the old code, so this just includes the change.