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rustdoc: Only calculate trait_ref.self_ty() once in get_blanket_impls #82856

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rustdoc: Only calculate trait_ref.self_ty() once in get_blanket_impls #82856

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@jyn514 jyn514 commented Mar 7, 2021 •
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On crates with many blanket impls, such as stm32, this inner closure
is executed many hundreds of thousands of times. This makes it very
slightly faster, since self_ty (which calls type_at) does non-trivial work:

rust/compiler/rustc_middle/src/ty/subst.rs

Lines 301 to 307 in dfe519b

pub fn type_at(&self, i: usize) -> Ty<'tcx> {
if let GenericArgKind::Type(ty) = self[i].unpack() {
ty
} else {
bug!("expected type for param #{} in {:?}", i, self);
}
}

Unfortunately, I don't have a good test case for showing that it's
faster until rust-lang/rustc-perf#802 is merged.

@jyn514
Only calculate trait_ref.self_ty() once in get_blanket_impls
8b5bc95 
On crates with many blanket impls, such as `stm32`, this inner closure
is executed many hundreds of thousands of times. This makes it very
slightly faster.

Unfortunately, I don't have a good test case for showing that it's
faster until rust-lang/rustc-perf#802 is merged.
@jyn514 jyn514 added T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. I-compiletime Issue: Problems and improvements with respect to compile times. labels Mar 7, 2021
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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 7, 2021
@jyn514 jyn514 changed the title Only calculate trait_ref.self_ty() once in get_blanket_impls rustdoc: Only calculate trait_ref.self_ty() once in get_blanket_impls Mar 7, 2021
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The job x86_64-gnu-llvm-9 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot) 
Suite("src/test/assembly") not skipped for "bootstrap::test::Assembly" -- not in ["src/tools/tidy"]
Check compiletest suite=assembly mode=assembly (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)

running 29 tests
iiiiiiiiiiiiiiiiiiiiiiiiiiiii

 finished in 0.064 seconds
Suite("src/test/incremental") not skipped for "bootstrap::test::Incremental" -- not in ["src/tools/tidy"]
Check compiletest suite=incremental mode=incremental (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
---
Suite("src/test/debuginfo") not skipped for "bootstrap::test::Debuginfo" -- not in ["src/tools/tidy"]
Check compiletest suite=debuginfo mode=debuginfo (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)

running 116 tests
iiiiiiiiii.i.i..i..i..ii....i.i....ii..........iiii.........i.....i...i.......ii.i.ii.....iiii.....i 100/116
test result: ok. 78 passed; 0 failed; 38 ignored; 0 measured; 0 filtered out; finished in 2.52s

 finished in 2.591 seconds
Suite("src/test/ui-fulldeps") not skipped for "bootstrap::test::UiFullDeps" -- not in ["src/tools/tidy"]
---
Check compiletest suite=rustdoc mode=rustdoc (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
warning: `tidy` is not installed; generated diffs will be harder to read

running 427 tests
.............F........................i..................................................F.......... 100/427
.................................................................................................F.. 300/427
.................................................................................................F.. 300/427
..................................F.........i............................F.......................... 400/427
Some tests failed in compiletest suite=rustdoc mode=rustdoc host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
failures:

---- [rustdoc] rustdoc/blanket-reexport-item.rs stdout ----
---- [rustdoc] rustdoc/blanket-reexport-item.rs stdout ----

error: htmldocck failed!
status: exit code: 1
command: "/usr/bin/python3" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/blanket-reexport-item" "/checkout/src/test/rustdoc/blanket-reexport-item.rs"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
3: @has check failed
 `XPATH PATTERN` did not match
 // @has foo/struct.S.html '//h3[@id="impl-Into%3CU%3E"]//code' 'impl<T, U> Into<U> for T'
Encountered 1 errors

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


info: generating a diff against nightly rustdoc
thread '[rustdoc] rustdoc/blanket-reexport-item.rs' panicked at 'failed to exec `"rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/blanket-reexport-item/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/blanket-reexport-item.nightly" "/checkout/src/test/rustdoc/blanket-reexport-item.rs"`', src/tools/compiletest/src/runtest.rs:1872:33

---- [rustdoc] rustdoc/generic-impl.rs stdout ----


error: htmldocck failed!
status: exit code: 1
command: "/usr/bin/python3" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/generic-impl" "/checkout/src/test/rustdoc/generic-impl.rs"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
8: @has check failed
 `XPATH PATTERN` did not match
 // @has foo/struct.Foo.html '//h3[@id="impl-ToString"]//code' 'impl<T> ToString for T'
10: @has check failed
 `XPATH PATTERN` did not match
 // @has foo/struct.Foo.html '//div[@class="sidebar-links"]/a[@href="#impl-ToString"]' 'ToString'
Encountered 2 errors

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


info: generating a diff against nightly rustdoc
thread '[rustdoc] rustdoc/generic-impl.rs' panicked at 'failed to exec `"rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/generic-impl/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/generic-impl.nightly" "/checkout/src/test/rustdoc/generic-impl.rs"`', src/tools/compiletest/src/runtest.rs:1872:33
---- [rustdoc] rustdoc/issue-78673.rs stdout ----


error: htmldocck failed!
status: exit code: 1
command: "/usr/bin/python3" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/issue-78673" "/checkout/src/test/rustdoc/issue-78673.rs"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
20: @has check failed
 `XPATH PATTERN` did not match
 // @has - '//*[@class="impl"]' 'AnAmazingTrait for T'
Encountered 1 errors

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


info: generating a diff against nightly rustdoc
thread '[rustdoc] rustdoc/issue-78673.rs' panicked at 'failed to exec `"rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/issue-78673/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/issue-78673.nightly" "/checkout/src/test/rustdoc/issue-78673.rs"`', src/tools/compiletest/src/runtest.rs:1872:33
---- [rustdoc] rustdoc/primitive-generic-impl.rs stdout ----


error: htmldocck failed!
status: exit code: 1
command: "/usr/bin/python3" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/primitive-generic-impl" "/checkout/src/test/rustdoc/primitive-generic-impl.rs"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
5: @has check failed
 `XPATH PATTERN` did not match
 // @has foo/primitive.i32.html '//h3[@id="impl-ToString"]//code' 'impl<T> ToString for T'
Encountered 1 errors

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


info: generating a diff against nightly rustdoc
thread '[rustdoc] rustdoc/primitive-generic-impl.rs' panicked at 'failed to exec `"rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/primitive-generic-impl/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/primitive-generic-impl.nightly" "/checkout/src/test/rustdoc/primitive-generic-impl.rs"`', src/tools/compiletest/src/runtest.rs:1872:33
---- [rustdoc] rustdoc/src-links-auto-impls.rs stdout ----


error: htmldocck failed!
status: exit code: 1
command: "/usr/bin/python3" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/src-links-auto-impls" "/checkout/src/test/rustdoc/src-links-auto-impls.rs"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
8: @has check failed
 `XPATH PATTERN` did not match
 // @has - '//h3[@id="impl-Any"]/code' 'impl<T> Any for T'
9: @has check failed
 `XPATH PATTERN` did not match
 // @has - '//h3[@id="impl-Any"]/a[@class="srclink"]' '[src]'
Encountered 2 errors

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


info: generating a diff against nightly rustdoc
thread '[rustdoc] rustdoc/src-links-auto-impls.rs' panicked at 'failed to exec `"rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/src-links-auto-impls/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/src-links-auto-impls.nightly" "/checkout/src/test/rustdoc/src-links-auto-impls.rs"`', src/tools/compiletest/src/runtest.rs:1872:33

failures:
    [rustdoc] rustdoc/blanket-reexport-item.rs
    [rustdoc] rustdoc/generic-impl.rs
---
test result: FAILED. 420 passed; 5 failed; 2 ignored; 0 measured; 0 filtered out; finished in 34.84s



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" "--rustdoc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustdoc" "--src-base" "/checkout/src/test/rustdoc" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--suite" "rustdoc" "--mode" "rustdoc" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-9/bin/FileCheck" "--nodejs" "/usr/bin/node" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -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" "9.0.0" "--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 codegen core coroutines coverage debuginfocodeview debuginfodwarf debuginfogsym debuginfomsf debuginfopdb demangle dlltooldriver engine executionengine 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 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" "" "--color" "always"


failed to run: /checkout/obj/build/bootstrap/debug/bootstrap --stage 2 test --exclude src/tools/tidy
Build completed unsuccessfully in 0:17:42

@jyn514
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jyn514 commented Mar 7, 2021

trait_ref on line 47 has the parameters substituted, so it's no longer the same as the one on line 35.

@jyn514 jyn514 closed this Mar 7, 2021
@jyn514 jyn514 deleted the fast-blanket-impls branch March 7, 2021 16:48
@jyn514 jyn514 mentioned this pull request Mar 7, 2021
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 29, 2021
@bors
Auto merge of rust-lang#82864 - jyn514:short-circuit, r=GuillaumeGomez
50489e3 
rustdoc: Don't enter an infer_ctxt in get_blanket_impls for impls that aren't blanket impls

Less broken version of rust-lang#82856.

get_blanket_impls is a *very* hot region of rustdoc, so even small changes like this should help. Unfortunately I don't have benchmarks for this until rust-lang/rustc-perf#802 is merged.
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