Add storeStoreFence Opcode for storeStoreFence intrinsic #19298
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
jmesyou
force-pushed
the
intrinsics/storeStoreFence
branch
from
b564c4e
to
b9c6f15
Compare
This commit adds the storeStoreFence opcode to represent StoreStore barrier semantics for Java. This barrier is provided as a Java class library `@IntrinsicCandidate` with `Unsafe.storeStoreFence()`. Code generation functionality is added for each backend where appropriate. StoreStore barriers in Java prevent the reordering of store operations before and after the barrier. Currently, this barrier is implemented through the storeFence opcode, which provides additional but unneeded reordering guarantees. The following extensions have been added for each backend that currently handles the storeFence opcode. - On x86, storeStoreFence is implemented as a `nop` - On arm64, storeStoreFence is implemented as `dmb ishst` see (eclipse-openj9#6332) - On power, storeStoreFence is implemented with a `lwsync` - On Z, storeFence is unused, so storeStoreFence is unimplemented. Signed-off-by: James You <james.you@protonmail.com>
jmesyou
force-pushed
the
intrinsics/storeStoreFence
branch
from
b9c6f15
to
546b727
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Outdated suggestions cannot be applied.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.
This commit adds the
storeStoreFence opcodeto represent StoreStore barrier semantics for Java. This barrier is provided as a Java class library@IntrinsicCandidatewithUnsafe.storeStoreFence(). Code generation functionality is added for each backend where appropriate.StoreStore barriers in Java prevent the reordering of store operations before and after the barrier. Currently, this barrier is implemented through the storeFence opcode, which provides additional but unneeded reordering guarantees.
The following extensions have been added for each backend which currently handles the storeFence opcode.
storeStoreFenceis implemented as anopstoreStoreFenceis implemented asdmb ishstsee (Investigate best AArch64 instructions for memory fences #6332)storeStoreFenceis implemented with alwsyncstoreFenceis unused, sostoreStoreFenceis unimplemented.Depends on: eclipse/omr#7310