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| author | bors <bors@rust-lang.org> | 2023-05-11 23:26:55 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2023-05-11 23:26:55 +0000 |
| commit | 5b24e12785e6a6bacb69953fb389bcd2fc11ae87 (patch) | |
| tree | 3eb9d69f5ecb64af4ab0a034bbe4323ddfcc7da2 /compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp | |
| parent | 2a8221dbdfd180a2d56d4b0089f4f3952d8c2bcd (diff) | |
| parent | 15aa7fad7ec83db399c8a85c6b6777d0efc7bc53 (diff) | |
| download | rust-5b24e12785e6a6bacb69953fb389bcd2fc11ae87.tar.gz rust-5b24e12785e6a6bacb69953fb389bcd2fc11ae87.zip | |
Auto merge of #111395 - scottmcm:slice-iter-zst-experiment, r=the8472
Simplify the implementation of iterators over slices of ZSTs Currently, slice iterators over ZSTs store `end = start.wrapping_byte_add(len)`. That's slightly convenient for `is_empty`, but kinda annoying for pretty much everything else -- see bugs like #42789, for example. This PR instead changes it to just `end = ptr::invalid(len)` instead. That's easier to think about (IMHO, at least) as well as easier to represent. `next` is still to big to get inlined into the mir-opt/pre-codegen/ tests, but if I bump the inline threshold to force it to show the whole thing, this implementation is also less MIR: ``` > git diff --numstat 241 370 tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.mir 255 329 tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.mir 184 216 tests/mir-opt/pre-codegen/slice_iter.slice_iter_mut_next_back.PreCodegen.after.mir 182 254 tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.mir ``` (That's ≈70 lines less for `Iter::next`, for example.) r? `@ghost` ~~Built atop #111282, so draft until that lands.~~
Diffstat (limited to 'compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp')
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