RocketTile: do not distort placement when hartid is not constant #2432
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
hcook
approved these changes
Apr 24, 2020
|
mark as multi-cycle path instead of adding registers? |
|
Need some Chisel support for that, and a bunch of other infrastructural plumbing for different tools. Until that exists, the tiny number of flops is fine. |
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Outdated suggestions cannot be applied.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.
When hartid is not a constant, driving it to the I$ D$ and CSR file directly from a Tile IO distorts placement of the core. These registers alleviate that.
However, when the hartid IS a constant, these registers are unneeded. I believe chisel will eliminate the registers via constant propagation.
Type of change: other enhancement
Impact: no functional change
Development Phase: implementation
Release Notes
Pipeline tile hartid input.