ArmEmitter: Support single use forward labels #3363
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
The delinker step of the JIT was using std::function with capture lambdas that required memory allocation when unnecessary. Because the compiler can't see through our std::function usage it could never decompose these by itself. By passing the Thread's frame and record to the function as arguments then we can have the signature be a raw function pointer. This fixes an area of concern from: https://github.com/FEX-Emu/FEX/blob/main/docs/ProgrammingConcerns.md#stdfunction-and-lambdas
Currently all uses of the forward label calls in to jemalloc to allocate memory. This allows a forward label that doesn't require any memory allocation, which is the common case in FEX.
Primary goal for this is to ensure that the delinker doesn't need to allocate any memory. This delinker can end up getting hit heavily with JIT code so we don't want it to be allocating memory.
Sonicadvance1
force-pushed
the
fix_label_allocations
branch
from
cc17bf6 to
3710240
Compare
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Outdated suggestions cannot be applied.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.
Needs #3361 merged first.Previously forward labels needed to be pessimistic about multiple instructions binding to a label. This results in forward labels having a vector that always allocates memory. Instead if we know the data is only going to be used by a single instruction then we don't need to allocate any memory. This is the common case in FEX.
In particular the delinker step for the JIT blocks was always allocating memory due to the forward label. Now it no longer allocates any memory since it uses a single use forward label.