Add a tier 3 target for the Sony PlayStation 1

[ayrtonm]

This adds a tier 3 target, mipsel-sony-psx, for the Sony PlayStation 1. I've tested it pretty thoroughly with this SDK I wrote for it.

From the tier 3 target policy (I've omitted the subpoints for brevity, but read over everything)

A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)

I'd be the designated developer

Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.

The target name follows the conventions of the existing PSP target (mipsel-sony-psp) and uses psx following the convention of the broader PlayStation homebrew community.

Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.

No legal issues with this target.

Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.

👍

Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.

The psx supports core and alloc, but will likely not support std anytime soon.

The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.

This target has an SDK and a cargo-psx tool for formatting binaries as psx executables. Documentation and examples are provided in the psx-sdk-rs README, the SDK and cargo tool are both available through crates.io and docs.rs has SDK documentation.

Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via @) to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.

👍

Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.

No problem

[rust-highfive]

r? @cjgillot

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

[rust-highfive]

⚠️ Warning ⚠️

• These commits modify compiler targets. (See the Target Tier Policy.)

[Urgau]

To speed up the review of this PR, can you add an entry in src/doc/rustc/src/platform-support with the new target name and as content the description of the new target, example here.

[heavyrain266]

How did you managed to get LLVM work on PSX? It's not officially supported target, though

I mean like, you cannot even cross compile to it from any other OS due to unsupported CPU architecture.

[bjorn3]

LLVM supports MIPS-I at least partially. A quick search leads to at least one change for supporting it: https://reviews.llvm.org/D122427

[ayrtonm]

Yeah -mcpu=mips1 was enabled in the patch @bjorn3 linked. That fixed the biggest issue which was miscompilations due to lack of support for load delay slots. The remaining issues are

• missing load delay slots in asm with .set reorder
• missing coprocessor instructions
• llvm tries lowering ATOMIC_FENCEs to a mips2 sync and crashes

The last one is the reason why atomics are currently disabled for this target and also means compiler_fences don't work, but there's a patch I'm planning on upstreaming.

[ayrtonm]

@Urgau I added a platform-support page.

[ayrtonm]

@rustbot label -S-waiting-on-author +S-waiting-on-review

[cjgillot]

Sorry for the slow review.
@bors r+

[bors]

📌 Commit d03185e has been approved by cjgillot

It is now in the queue for this repository.