Avoid many cmt allocations.
#50418
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Avoid many cmt allocations.
#50418
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`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%.
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r? @estebank (rust_highfive has picked a reviewer for you, use r? to override) |
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Could a compiler pass be added to perform this optimization (escape analysis?)? |
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LGTM. r? @petrochenkov or @eddyb for a second pair of eyes. |
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Welp, all of this ancient code will hopefully go away once MIR borrowck takes over. |
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📌 Commit 7cf142f has been approved by |
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@Manishearth: note that this will break Clippy. The fix will be easy, just updating method arguments for the changes in the |
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sounds good, thanks for the heads up! |
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⌛ Testing commit 7cf142f with merge f86297d51946264715934bafd69c6c9315f80594... |
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💔 Test failed - status-appveyor |
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The failure is: Infrastructure failure? Worth a retry? |
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@bors retry |
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cc #48775 |
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⌛ Testing commit 7cf142f with merge a19e9ece9c3a52c20c96c3a6d337c8d193a94e6b... |
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💔 Test failed - status-travis |
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Which is #43283. Can somebody please retry? |
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@bors r=eddyb |
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💡 This pull request was already approved, no need to approve it again.
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📌 Commit 7cf142f has been approved by |
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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%.
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☀️ Test successful - status-appveyor, status-travis |
This was referenced May 6, 2018
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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%.