Avoid many cmt allocations.
#50418
Merged
Avoid many cmt allocations.
#50418
Conversation
This file contains hidden or 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
`cmt` is a ref-counted wrapper around `cmt_` The use of refcounting keeps `cmt` handling simple, but a lot of `cmt` instances are very short-lived, and heap-allocating the short-lived ones takes up time. This patch changes things in the following ways. - Most of the functions that produced `cmt` instances now produce `cmt_` instances. The `Rc::new` calls that occurred within those functions now occur at their call sites (but only when necessary, which isn't that often). - Many of the functions that took `cmt` arguments now take `&cmt_` arguments. This includes all the methods in the `Delegate` trait. As a result, the vast majority of the heap allocations are avoided. In an extreme case, the number of calls to malloc in tuple-stress drops from 9.9M to 7.9M, a drop of 20%. And the compile times for many runs of coercions, deep-vector, and tuple-stress drop by 1--2%.
|
r? @estebank (rust_highfive has picked a reviewer for you, use r? to override) |
rust-highfive
added
the
S-waiting-on-review
|
Could a compiler pass be added to perform this optimization (escape analysis?)? |
|
LGTM. r? @petrochenkov or @eddyb for a second pair of eyes. |
|
Welp, all of this ancient code will hopefully go away once MIR borrowck takes over. |
|
📌 Commit 7cf142f has been approved by |
bors
added
S-waiting-on-bors
|
@Manishearth: note that this will break Clippy. The fix will be easy, just updating method arguments for the changes in the |
|
sounds good, thanks for the heads up! |
|
⌛ Testing commit 7cf142f with merge f86297d51946264715934bafd69c6c9315f80594... |
|
💔 Test failed - status-appveyor |
bors
added
S-waiting-on-review
|
The failure is: Infrastructure failure? Worth a retry? |
|
@bors retry |
bors
added
S-waiting-on-bors
|
cc #48775 |
|
⌛ Testing commit 7cf142f with merge a19e9ece9c3a52c20c96c3a6d337c8d193a94e6b... |
|
💔 Test failed - status-travis |
bors
added
S-waiting-on-review
This comment has been minimized.
This comment has been minimized.
1 similar comment
This comment has been minimized.
This comment has been minimized.
Which is #43283. Can somebody please retry? |
|
@bors r=eddyb |
|
💡 This pull request was already approved, no need to approve it again.
|
|
📌 Commit 7cf142f has been approved by |
bors
added
S-waiting-on-bors
bors
added a commit
that referenced
this pull request
May 5, 2018
Avoid many `cmt` allocations. `cmt` is a ref-counted wrapper around `cmt_` The use of refcounting keeps `cmt` handling simple, but a lot of `cmt` instances are very short-lived, and heap-allocating the short-lived ones takes up time. This patch changes things in the following ways. - Most of the functions that produced `cmt` instances now produce `cmt_` instances. The `Rc::new` calls that occurred within those functions now occur at their call sites (but only when necessary, which isn't that often). - Many of the functions that took `cmt` arguments now take `&cmt_` arguments. This includes all the methods in the `Delegate` trait. As a result, the vast majority of the heap allocations are avoided. In an extreme case, the number of calls to malloc in tuple-stress drops from 9.9M to 7.9M, a drop of 20%. And the compile times for many runs of coercions, deep-vector, and tuple-stress drop by 1--2%.
|
☀️ Test successful - status-appveyor, status-travis |
This was referenced May 6, 2018
Merged
# for free
to join this conversation on GitHub.
Already have an account?
# 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.
cmtis a ref-counted wrapper aroundcmt_The use of refcountingkeeps
cmthandling simple, but a lot ofcmtinstances are veryshort-lived, and heap-allocating the short-lived ones takes up time.
This patch changes things in the following ways.
Most of the functions that produced
cmtinstances now producecmt_instances. The
Rc::newcalls that occurred within those functionsnow occur at their call sites (but only when necessary, which isn't
that often).
Many of the functions that took
cmtarguments now take&cmt_arguments. This includes all the methods in the
Delegatetrait.As a result, the vast majority of the heap allocations are avoided. In
an extreme case, the number of calls to malloc in tuple-stress drops
from 9.9M to 7.9M, a drop of 20%. And the compile times for many runs of
coercions, deep-vector, and tuple-stress drop by 1--2%.