95979dcfb2
Specialize StepBy<Range(Inclusive)> Part of #51557, related to #43064, #31155 As discussed in the above issues, `step_by` optimizes very badly on ranges which is related to 1. the special casing of the first `StepBy::next()` call 2. the need to do 2 additions of `n - 1` and `1` inside the range's `next()` This PR eliminates both by overriding `next()` to always produce the current element and also step ahead by `n` elements in one go. The generated code is much better, even identical in the case of a `Range` with constant `start` and `end` where `start+step` can't overflow. Without constant bounds it's a bit longer than the manual loop. `RangeInclusive` doesn't optimize as nicely but is still much better than the original asm. Unsigned integers optimize better than signed ones for some reason. See the following two links for a comparison. [godbolt: specialization for ..](https://godbolt.org/g/haHLJr) [godbolt: specialization for ..=](https://godbolt.org/g/ewyMu6) `RangeFrom`, the only other range with an `Iterator` implementation can't be specialized like this without changing behaviour due to overflow. There is no way to save "finished-ness". The approach can not be used in general, because it would produce side effects of the underlying iterator too early. May obsolete #51435, haven't checked. |
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| .. | ||
| bootstrap | ||
| build_helper | ||
| ci | ||
| dlmalloc@c99638dc2e | ||
| doc | ||
| etc | ||
| grammar | ||
| jemalloc@1f5a28755e | ||
| liballoc | ||
| liballoc_jemalloc | ||
| liballoc_system | ||
| libarena | ||
| libbacktrace@f4d02bbdbf | ||
| libcompiler_builtins@4cfd7101eb | ||
| libcore | ||
| libfmt_macros | ||
| libgraphviz | ||
| liblibc@a7e78a78e1 | ||
| libpanic_abort | ||
| libpanic_unwind | ||
| libproc_macro | ||
| libprofiler_builtins | ||
| librustc | ||
| librustc_allocator | ||
| librustc_apfloat | ||
| librustc_asan | ||
| librustc_borrowck | ||
| librustc_codegen_llvm | ||
| librustc_codegen_utils | ||
| librustc_cratesio_shim | ||
| librustc_data_structures | ||
| librustc_driver | ||
| librustc_errors | ||
| librustc_incremental | ||
| librustc_lint | ||
| librustc_llvm | ||
| librustc_lsan | ||
| librustc_metadata | ||
| librustc_mir | ||
| librustc_msan | ||
| librustc_passes | ||
| librustc_platform_intrinsics | ||
| librustc_plugin | ||
| librustc_privacy | ||
| librustc_resolve | ||
| librustc_save_analysis | ||
| librustc_target | ||
| librustc_traits | ||
| librustc_tsan | ||
| librustc_typeck | ||
| librustdoc | ||
| libserialize | ||
| libstd | ||
| libstd_unicode | ||
| libsyntax | ||
| libsyntax_ext | ||
| libsyntax_pos | ||
| libterm | ||
| libtest | ||
| libunwind | ||
| llvm@9ad4b7e8d7 | ||
| llvm-emscripten@2717444753 | ||
| rtstartup | ||
| rustc | ||
| rustllvm | ||
| stdsimd@a19ca1cd91 | ||
| test | ||
| tools | ||
| Cargo.lock | ||
| Cargo.toml | ||
| README.md | ||
| stage0.txt | ||
This directory contains the source code of the rust project, including:
rustcand its testslibstd- Various submodules for tools, like rustdoc, rls, etc.
For more information on how various parts of the compiler work, see the rustc guide.
Their is also useful content in the following READMEs, which are gradually being moved over to the guide:
- https://github.com/rust-lang/rust/tree/master/src/librustc/ty/query
- https://github.com/rust-lang/rust/tree/master/src/librustc/dep_graph
- https://github.com/rust-lang/rust/blob/master/src/librustc/infer/region_constraints
- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/higher_ranked
- https://github.com/rust-lang/rust/tree/master/src/librustc/infer/lexical_region_resolve