[Experiment] Split exhaustiveness logic into its own crate #89570

Nadrieril · 2021-10-05T18:28:25Z

rust-analyzer currently maintains a patched copy of the exhaustiveness algorithm for their own analyses. That's too bad, so I factored out everything rustc-specific from the relevant files. If perf isn't killed, I'll move it into its own crate.

Until the type library gets librarified, there'll still be some nontrivial code that rust-analyzer will have to duplicate. But the core functionality will be shared and we should be able to implement cool features for the rust-analyzer side.

rust-highfive · 2021-10-05T18:28:28Z

r? @estebank

(rust-highfive has picked a reviewer for you, use r? to override)

Nadrieril · 2021-10-05T18:28:49Z

r? @ghost

And in the process greatly clarify how they're handled.

Instead of going through the complicated `IntRange` logic

Also rework const evaluation a bit

Nadrieril · 2021-10-06T01:08:49Z

@bors try @rust-timer queue

rust-timer · 2021-10-06T01:08:51Z

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

bors · 2021-10-06T01:08:58Z

⌛ Trying commit ec2324b with merge d333b4430fb1577f7c0f0e650ac2f49a6fd04048...

rust-log-analyzer · 2021-10-06T01:25:45Z

The job x86_64-gnu-llvm-10 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

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failures:


---- [ui] ui/unsafe/union_destructure.rs#mir stdout ----
diff of stderr:

+ warning: unreachable pattern
+   --> $DIR/union_destructure.rs:22:33
+    |
+ LL |     let (Some(Foo { bar: _ }) | Some(Foo { bar: _ }) | None) = Some(u);
+    |
+    = note: `#[warn(unreachable_patterns)]` on by default
+ 
+ warning: unreachable pattern
+ warning: unreachable pattern
+   --> $DIR/union_destructure.rs:25:28
+    |
+ LL |         let (Foo { bar } | Foo { bar }) = u;
+ 
+ 
1 warning: unnecessary `unsafe` block
3    |

12 LL |     unsafe {
Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
13    |     ^^^^^^ unnecessary `unsafe` block
- warning: 2 warnings emitted
+ warning: 4 warnings emitted
16 
17 
17 


The actual stderr differed from the expected stderr.
Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.mir/union_destructure.mir.stderr
To only update this specific test, also pass `--test-args unsafe/union_destructure.rs`


error in revision `mir`: 1 errors occurred comparing output.
status: exit status: 0
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/unsafe/union_destructure.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--cfg" "mir" "--error-format" "json" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zemit-future-incompat-report" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.mir/a" "-Crpath" "-O" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.mir/auxiliary"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
warning: unreachable pattern
  --> /checkout/src/test/ui/unsafe/union_destructure.rs:22:33
   |
LL |     let (Some(Foo { bar: _ }) | Some(Foo { bar: _ }) | None) = Some(u);
   |
   = note: `#[warn(unreachable_patterns)]` on by default

warning: unreachable pattern
warning: unreachable pattern
  --> /checkout/src/test/ui/unsafe/union_destructure.rs:25:28
   |
LL |         let (Foo { bar } | Foo { bar }) = u;


warning: unnecessary `unsafe` block
   |
   |
LL |     unsafe { //[mir]~ WARNING unnecessary `unsafe` block
   |     ^^^^^^ unnecessary `unsafe` block
   = note: `#[warn(unused_unsafe)]` on by default


warning: unnecessary `unsafe` block
   |
   |
LL |     unsafe { //[mir]~ WARNING unnecessary `unsafe` block
   |     ^^^^^^ unnecessary `unsafe` block
warning: 4 warnings emitted


------------------------------------------
------------------------------------------


---- [ui] ui/unsafe/union_destructure.rs#thir stdout ----
normalized stderr:
warning: unreachable pattern
  --> $DIR/union_destructure.rs:22:33
   |
LL |     let (Some(Foo { bar: _ }) | Some(Foo { bar: _ }) | None) = Some(u);
   |
   = note: `#[warn(unreachable_patterns)]` on by default

warning: unreachable pattern
warning: unreachable pattern
  --> $DIR/union_destructure.rs:25:28
   |
LL |         let (Foo { bar } | Foo { bar }) = u;

warning: 2 warnings emitted





The actual stderr differed from the expected stderr.
Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.thir/union_destructure.thir.stderr
To only update this specific test, also pass `--test-args unsafe/union_destructure.rs`


error in revision `thir`: 1 errors occurred comparing output.
status: exit status: 0
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/unsafe/union_destructure.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--cfg" "thir" "--error-format" "json" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zemit-future-incompat-report" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.thir/a" "-Crpath" "-O" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-Z" "thir-unsafeck" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/unsafe/union_destructure.thir/auxiliary"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
warning: unreachable pattern
  --> /checkout/src/test/ui/unsafe/union_destructure.rs:22:33
   |
LL |     let (Some(Foo { bar: _ }) | Some(Foo { bar: _ }) | None) = Some(u);
   |
   = note: `#[warn(unreachable_patterns)]` on by default

warning: unreachable pattern
warning: unreachable pattern
  --> /checkout/src/test/ui/unsafe/union_destructure.rs:25:28
   |
LL |         let (Foo { bar } | Foo { bar }) = u;

warning: 2 warnings emitted


---
test result: FAILED. 12136 passed; 2 failed; 115 ignored; 0 measured; 0 filtered out; finished in 131.38s



command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--suite" "ui" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-10/bin/FileCheck" "--nodejs" "/usr/bin/node" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python3" "--lldb-python" "/usr/bin/python3" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "10.0.0" "--llvm-components" "aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils aggressiveinstcombine all all-targets amdgpu amdgpuasmparser amdgpucodegen amdgpudesc amdgpudisassembler amdgpuinfo amdgpuutils analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo cfguard codegen core coroutines coverage debuginfocodeview debuginfodwarf debuginfogsym debuginfomsf debuginfopdb demangle dlltooldriver dwarflinker engine executionengine frontendopenmp fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo instcombine instrumentation interpreter ipo irreader jitlink lanai lanaiasmparser lanaicodegen lanaidesc lanaidisassembler lanaiinfo libdriver lineeditor linker lto mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts object objectyaml option orcerror orcjit passes perfjitevents powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo riscvutils runtimedyld scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target textapi transformutils vectorize webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info x86utils xcore xcorecodegen xcoredesc xcoredisassembler xcoreinfo xray" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--channel" "nightly" "--color" "always"


Build completed unsuccessfully in 0:13:42

bors · 2021-10-06T02:30:16Z

☀️ Try build successful - checks-actions
Build commit: d333b4430fb1577f7c0f0e650ac2f49a6fd04048 (d333b4430fb1577f7c0f0e650ac2f49a6fd04048)

rust-timer · 2021-10-06T02:30:18Z

Queued d333b4430fb1577f7c0f0e650ac2f49a6fd04048 with parent 25ec827, future comparison URL.

rust-timer · 2021-10-06T04:40:45Z

Finished benchmarking commit (d333b4430fb1577f7c0f0e650ac2f49a6fd04048): comparison url.

Summary: This change led to moderate relevant regressions 😿 in compiler performance.

Moderate regression in instruction counts (up to 1.0% on incr-full builds of cranelift-codegen)

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf +perf-regression

nikomatsakis · 2021-10-18T12:42:16Z

This is exciting!

joshtriplett · 2021-10-30T23:19:52Z

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

    use Constructor::*;
    match pat.ctor() {
        Wildcard => true,
-        Single => pat.iter_fields().all(|pat| pat_is_catchall(pat)),
+        Single | Tuple(_) | Ref(_) | BoxPat(_) => pat.iter_fields().all(|pat| pat_is_catchall(pat)),


Is this a bugfix?

This seems like it might be a source of performance impact.

No, this is because I split the Single case into more specific subcases so that I could abstract it all in a trait. I suspected this could be the source of perf degradation but my local measurements don't show much impact from this.
The problem of course is that my local measurements don't match what rust-timer reports here so you could be right. When I get back to this I'll measure intermediate commits with rust-timer.

Nadrieril · 2021-11-01T12:26:18Z

(I still intend get this done. Will get back to it whenever my work deadlines are done and motivation strikes)

Dylan-DPC · 2022-09-22T09:29:17Z

Closing this as it is inactive

DevinR528 and others added 9 commits October 5, 2021 08:57

Filter unstable and doc hidden variants in exhaustive check

dc6c89a

Add test cases for unstable variants

068325b

Diagnostic output for unstable variant tests

6f86964

Add test cases for doc hidden variants

3dd5ad2

Diagnostic output for doc hidden variants

0d58694

Remove io::ErrorKind and update reachable-patterns diagnostic output

311333b

Fix behavior of doc hidden filtering

9927c1f

Cleanup check for unstable attributes on variants

b02590d

Move unstable patterns test to patterns/usefulness

5d5b381

Nadrieril added A-exhaustiveness-checking Relating to exhaustiveness / usefulness checking of patterns S-experimental Status: Ongoing experiment that does not require reviewing and won't be merged in its current state. labels Oct 5, 2021

rust-highfive assigned estebank Oct 5, 2021

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 5, 2021

Nadrieril added 15 commits October 5, 2021 19:44

Add a test

34d9075

Fix a comment

0f1dcc6

PatternFolder is no longer used

033aeb8

Add a constructor for box patterns

e8c10f5

And in the process greatly clarify how they're handled.

Add a constructor for ref patterns

25f0710

Add a constructor for tuple patterns

13c418f

Reorder the logic of SplitWildcard::new

2cb2a54

Add explicit constructors for bool values

3ca5461

Instead of going through the complicated `IntRange` logic

Evaluate consts earlier

4c286e2

Also rework const evaluation a bit

Don't lint from within the algorithm; collect instead

604b31b

Always report unreachable subpatterns

1684c64

Move conversion to/from thir::Pat out of deconstruct_pat

784d29a

Move abi-related computations out of deconstruct_pat

03eb4be

Reuse size since we have it

474e763

Move tcx-dependent code out of deconstruct_pat

c4f840d

Nadrieril added 2 commits October 6, 2021 01:50

Remove all matching on Ty from deconstruct_pat

f1e56c6

Thread everything rustc-dependent via a trait

ec2324b

Nadrieril force-pushed the split-exhaustiveness-into-crate branch from edde94a to ec2324b Compare October 6, 2021 01:07

Nadrieril unassigned estebank Oct 6, 2021

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 6, 2021

rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Oct 6, 2021

joshtriplett reviewed Oct 30, 2021

View reviewed changes

camelid added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 9, 2021

iDawer mentioned this pull request Nov 19, 2021

internal: Update match checking algorithm rust-lang/rust-analyzer#10484

Merged

1 task

camsteffen mentioned this pull request Jan 6, 2022

match_same_arms fix rust-lang/rust-clippy#8232

Merged

Dylan-DPC closed this Sep 22, 2022

Dylan-DPC removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Sep 22, 2022

Nadrieril deleted the split-exhaustiveness-into-crate branch December 11, 2023 22:35

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[Experiment] Split exhaustiveness logic into its own crate #89570

[Experiment] Split exhaustiveness logic into its own crate #89570

Nadrieril commented Oct 5, 2021

rust-highfive commented Oct 5, 2021

Nadrieril commented Oct 5, 2021

Nadrieril commented Oct 6, 2021

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bors commented Oct 6, 2021

rust-timer commented Oct 6, 2021

rust-timer commented Oct 6, 2021

nikomatsakis commented Oct 18, 2021

joshtriplett Oct 30, 2021

Nadrieril Nov 1, 2021

Nadrieril commented Nov 1, 2021

Dylan-DPC commented Sep 22, 2022

[Experiment] Split exhaustiveness logic into its own crate #89570

[Experiment] Split exhaustiveness logic into its own crate #89570

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Nadrieril commented Oct 5, 2021

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