Rollup of 7 pull requests #83864
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Rollup of 7 pull requests #83864
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This is step 2 towards fixing rust-lang#77548. In the codegen and codegen-units test suites, the `//` comment markers were kept in order not to affect any source locations. This is because these tests cannot be automatically `--bless`ed.
Co-authored-by: Yuki Okushi <jtitor@2k36.org>
Previously registers could only be marked as clobbered if the target feature for that register was enabled. This restriction is now removed.
wasm64 support There is still some upstream llvm work needed before this can land.
core: disable `ptr::swap_nonoverlapping_one`'s block optimization on SPIR-V. SPIR-V primarily supports what it calls the "Logical addressing model" (and AFAIK for graphical shaders it's the only option), and what that implies is that there is no "memory" to uniformly address at some byte/word level, and that you can't really talk about values having a "raw representation" in terms of sequences of bytes. Therefore, the "block"-wise swapping optimization employed by `ptr::swap_nonoverlapping_one` (where a "block" is 32 bytes, currently), is fundamentally incompatible with SPIR-V "memory". As such, [Rust-GPU](https://github.com/EmbarkStudios/rust-gpu/)'s `rustc_codegen_spirv` backend cannot currently allow the use of `ptr::swap_nonoverlapping_one` - but that comes at a great price, since it's the building block of `mem::{swap,replace}`, and those in turn are used by e.g. `Option::take` and `Range`'s `Iterator` implementation (the latter blocking the use of `for i in 0..n` loops). There's 4 options I can see in terms of supporting `ptr::swap_nonoverlapping_one` in `rustc_codegen_spirv`: * legalize the block-wise swap loop back into swapping whole values, for SPIR-V * this is made borderline impossible by the fact that the size of the state "on the stack" is a block, and has to be expanded back to the appropriate size of the value being swapped, so in practice this would have to effectively pattern-match on the exact shape of the block-wise swapping algorithm, as a roundabout way of "patching `core::ptr` on the fly" * (**this PR**) disable the block-wise swap optimization altogether when `#[cfg(target_arch = "spirv")` * I've tested it and it does in fact allow compiling `for i in 0..n` loops, which was my primary motivation * main downside IMO is the fact that `core` now acknowledges an out-of-tree backend * as a counterpoint, any attempt to compile Rust to SPIR-V would run into this problem, one way or another * only enable the block-wise swap optimization on targets where it's been empirically proven to be an improvement * would avoid any surprises in terms of potentially-broken/inefficient codegen, in general * however, it may be universally applicable (thanks to caches), even if the optimal block size could differ * move low-level swapping into an intrinsic, where the backend can choose any optimization approach it wants * this also has an impact on MIR optimizations (cc ``@rust-lang/wg-mir-opt)`` - which currently cannot hope to make sense of e.g. `Option::take` despite it being effectively `_0 = *_1;` `*_1 = None;` `return;` * long-term this is my preferred approach, and I can start working on it if that's desired, but I wanted to confirm that this swapping optimization is the final blocker for [Rust-GPU](https://github.com/EmbarkStudios/rust-gpu/) supporting e.g. range `for` loops r? ``@nagisa`` cc ``@rust-lang/libs``
…llaumeGomez rustdoc: Separate filter-empty-string out into its own function
…ions, r=Mark-Simulacrum Tests: Remove redundant `ignore-tidy-linelength` annotations This is step 2 towards fixing rust-lang#77548. In the codegen and codegen-units test suites, the `//` comment markers were kept in order not to affect any source locations. This is because these tests cannot be automatically `--bless`ed.
ptr::addr_of documentation improvements While writing rust-lang/reference#1001 I figured I could also improve the docs here a bit.
Remove attribute `#[link_args]` Closes rust-lang#29596 The attribute could always be replaced with `-C link-arg`, but cargo didn't provide a reasonable way to pass such flags to rustc. Now cargo supports `cargo:rustc-link-arg*` directives in build scripts (https://doc.rust-lang.org/cargo/reference/unstable.html#extra-link-arg), so this attribute can be removed.
Allow clobbering unsupported registers in asm! Previously registers could only be marked as clobbered if the target feature for that register was enabled. This restriction is now removed. cc rust-lang#81092 r? ``@nagisa``
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@bors r+ rollup=never p=5 |
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📌 Commit f8709ec has been approved by |
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☀️ Test successful - checks-actions |
This was referenced Apr 5, 2021
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Successful merges:
ptr::swap_nonoverlapping_one's block optimization on SPIR-V. #83019 (core: disableptr::swap_nonoverlapping_one's block optimization on SPIR-V.)ignore-tidy-linelengthannotations #83807 (Tests: Remove redundantignore-tidy-linelengthannotations)#[link_args]#83820 (Remove attribute#[link_args])Failed merges:
r? @ghost
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