[TableGen] Efficiency improvements for encoding HwMode collection. #82902
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
Currently the DecoderEmitter spends a fair amount of cycles performing repeated linear walks over the entire instruction list. This patch eliminates one such walk during HwMode collection for EncodingInfos. The eliminated traversal visits every instruction and then every EncodingInfos entry for that instruction merely to collect all referenced HwModes. That information already happens to be present in the HwModeSelects created during the one-time construction of CodeGenHwModes. We instead traverse the HwModeSelects, collecting each one referenced as an encoding select. This set is a small constant in size and does not generally grow with the size of the instruction set.
|
I hope one of @topperc @jyknight @jmolloy @0x59616e @wangpc-pp (based on recent commits or past reviews to the same general area) might review this small patch, thank you. |
Thank you @wangpc-pp , could I also trouble you to merge on my behalf? (will apply for write access soon, almost enough commits). |
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Outdated suggestions cannot be applied.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.
Currently the DecoderEmitter spends a fair amount of cycles performing repeated linear walks over the entire instruction list. This patch eliminates one such walk during HwMode collection for EncodingInfos.
The eliminated traversal visits every instruction and then every EncodingInfos entry for that instruction merely to collect all referenced HwModes. That information already happens to be present in the HwModeSelects created during the one-time construction of CodeGenHwModes. We instead traverse the HwModeSelects, collecting each one referenced as an encoding select. This set is a small constant in size and does not generally grow with the size of the instruction set.