rustc: precompute the largest Niche and store it in LayoutDetails.#62692

eddyb · 2019-07-15T16:00:11Z

Since we only ever can use at most one niche, it makes sense to just store that in the layout, for the simplest caching (especially as it's almost trivial to compute).

There might be a speedup from this, but even if it's marginal now, the caching would be a more significant benefit for future optimization attempts.

rust-highfive · 2019-07-15T16:00:15Z

r? @matthewjasper

(rust_highfive has picked a reviewer for you, use r? to override)

eddyb · 2019-07-15T16:01:13Z

@bors try

bors · 2019-07-15T16:01:25Z

⌛ Trying commit 88eced5 with merge 7e03358...

rustc: precompute the largest Niche and store it in LayoutDetails. Since we only ever can use at most one niche, it makes sense to just store that in the layout, for the simplest caching (especially as it's almost trivial to compute). There might be a speedup from this, but even if it's marginal now, the caching would be a more significant benefit for future optimization attempts.

bors · 2019-07-15T18:46:20Z

☀️ Try build successful - checks-azure
Build commit: 7e03358

eddyb · 2019-07-16T03:41:18Z

@rust-timer build 7e03358

rust-timer · 2019-07-16T03:41:19Z

Success: Queued 7e03358 with parent 92b0f52, comparison URL.

rust-timer · 2019-07-16T06:12:11Z

Finished benchmarking try commit 7e03358, comparison URL.

eddyb · 2019-07-16T10:25:21Z

cc @rkruppe @nagisa @oli-obk

eddyb · 2019-07-18T14:35:22Z

@oli-obk Is that a "r=me", or do you want to wait on other people?

oli-obk · 2019-07-20T15:01:15Z

@bors r+

yea, sorry, I was confused

bors · 2019-07-20T15:01:16Z

📌 Commit 88eced5 has been approved by oli-obk

bjorn3 · 2019-07-20T18:26:50Z

src/librustc/ty/layout.rs

        let b_offset = a.value.size(dl).align_to(b_align.abi);
        let size = (b_offset + b.value.size(dl)).align_to(align.abi);
+
+        // HACK(nox): We iter on `b` and then `a` because `max_by_key`


Why @nox here? According to git all comments are authored by @eddyb.

If you search for "nox" in this diff you can see where the code was copied from

Missed that :)

bors · 2019-07-21T12:33:32Z

⌛ Testing commit 88eced5 with merge 6945455ed42f049c4d5380762ef9b5bae090062a...

Centril · 2019-07-21T12:36:44Z

@bors retry Yielding to #62797.

rustc: precompute the largest Niche and store it in LayoutDetails. Since we only ever can use at most one niche, it makes sense to just store that in the layout, for the simplest caching (especially as it's almost trivial to compute). There might be a speedup from this, but even if it's marginal now, the caching would be a more significant benefit for future optimization attempts.

@ghost

Rollup of 14 pull requests Successful merges: - #62084 (allow clippy::unreadable_literal in unicode tables) - #62421 (Introduce `as_deref` to Option) - #62692 (rustc: precompute the largest Niche and store it in LayoutDetails.) - #62801 (Remove support for -Zlower-128bit-ops) - #62828 (Remove vector fadd/fmul reduction workarounds) - #62862 (code cleanup) - #62897 (Attempt to fix backtrace tests on i686-msvc) - #62904 (Disable d32 on armv6 hf targets) - #62907 (Initialize the MSP430 AsmParser) - #62956 (Implement slow-path for FirstSets::first) - #62963 (Allow lexer to recover from some homoglyphs) - #62970 (ci: gate toolstate repo pushes on the TOOLSTATE_PUBLISH envvar) - #62983 (Remove needless indirection through Rc) - #62985 (librustc_errors: Support ui-testing flag in annotate-snippet emitter) Failed merges: r? @ghost

rustc: precompute the largest Niche and store it in LayoutDetails. Since we only ever can use at most one niche, it makes sense to just store that in the layout, for the simplest caching (especially as it's almost trivial to compute). There might be a speedup from this, but even if it's marginal now, the caching would be a more significant benefit for future optimization attempts.

@ghost

Rollup of 22 pull requests Successful merges: - #62084 (allow clippy::unreadable_literal in unicode tables) - #62120 (Add missing type links in documentation) - #62310 (Add missing doc links in boxed module) - #62421 (Introduce `as_deref` to Option) - #62583 (Implement Unpin for all raw pointers) - #62692 (rustc: precompute the largest Niche and store it in LayoutDetails.) - #62801 (Remove support for -Zlower-128bit-ops) - #62828 (Remove vector fadd/fmul reduction workarounds) - #62862 (code cleanup) - #62904 (Disable d32 on armv6 hf targets) - #62907 (Initialize the MSP430 AsmParser) - #62956 (Implement slow-path for FirstSets::first) - #62963 (Allow lexer to recover from some homoglyphs) - #62964 (clarify and unify some type test names) - #62970 (ci: gate toolstate repo pushes on the TOOLSTATE_PUBLISH envvar) - #62980 (std: Add more accessors for `Metadata` on Windows) - #62983 (Remove needless indirection through Rc) - #62985 (librustc_errors: Support ui-testing flag in annotate-snippet emitter) - #63002 (error_index_generator should output stdout/stderr when it panics.) - #63004 (Add test for issue-54062) - #63007 (ci: debug network failures while downloading awscli from PyPI) - #63009 (Remove redundant `mut` from variable declaration.) Failed merges: r? @ghost

eddyb added 3 commits July 15, 2019 18:41

rustc: compute ty::layout::Niche's available on the fly.

8c050fc

rustc_target: move abi::Niche from rustc::ty::layout.

dfbf464

rustc: precompute the largest Niche and store it in LayoutDetails.

88eced5

rust-highfive assigned matthewjasper Jul 15, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 15, 2019

oli-obk approved these changes Jul 18, 2019

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eddyb mentioned this pull request Jul 18, 2019

Make niches part of layout and expand call ABI rust-lang/unsafe-code-guidelines#153

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 20, 2019

bjorn3 reviewed Jul 20, 2019

View reviewed changes

Centril mentioned this pull request Jul 23, 2019

Rollup of 13 pull requests #62920

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Centril mentioned this pull request Jul 24, 2019

Rollup of 8 pull requests #62937

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Centril mentioned this pull request Jul 25, 2019

Rollup of 10 pull requests #62991

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Centril mentioned this pull request Jul 26, 2019

Rollup of 14 pull requests #63001

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Centril mentioned this pull request Jul 26, 2019

Rollup of 17 pull requests #63011

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Centril mentioned this pull request Jul 26, 2019

Rollup of 22 pull requests #63015

Merged

bors merged commit 88eced5 into rust-lang:master Jul 26, 2019

eddyb deleted the precompute-niches branch July 27, 2019 03:30

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