Full asm!() support

[bjorn3]

• Support const operands.
  • For inline asm (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1350)
  • For global asm (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1351)
• Support sym operands.
  • For inline asm (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1350)
  • For global asm (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1351, but doesn't work when the function is made private to the codegen unit)
• Support asm goto (Stabilize asm_goto feature gate rust#133870 will stabilize it for cg_llvm)
• Support register classes. This will require writing a mini register allocator to solve all register constraints. (Improve inline asm support #1206)
• Optimize
  • Overlap input and output stack slots. (Improve inline asm support #1206)
  • Skip saving caller saved registers. (Improve inline asm support #1206)
• Support more architectures
  • aarch64 (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1396)
  • riscv64 (Add riscv64 linux support #1398)
  • ...
• Support inline asm on macOS (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1397)
• Support inline asm on Windows (Support and stabilize inline asm on all platforms #1403)
• Avoid the object file linking hack. It doesn't work on macOS and Windows but is currently necessary as incr comp expects each codegen unit to provide a single object file instead of allowing an extra object file for the compiled assembly. (Refactorings for enabling parallel compilation (part 1) #1264)
• Use cgu name instead of function name as base for assembly stub names. The same function name may be used in multiple cgus when using #[inline]. (1222192)
• Run inline asm tests from the rustc test suite (https://github.com/bjorn3/rustc_codegen_cranelift/pull/1397)
• Enable support by default (Support and stabilize inline asm on all platforms #1403)

Tracking issue for stabilizing asm!(): rust-lang/rust#72016 Has been stabilized.

[bjorn3]

Avoid the object file linking hack. It doesn't work on macOS and Windows but is currently necessary as incr comp expects each codegen unit to provide a single object file instead of allowing an extra object file for the compiled assembly.

I managed to do this on the parallel_comp_refactor branch.

[bjorn3]

Merged in #1264.

[bjorn3]

Mostly implemented const and sym operands for both inline and global asm.

[bjorn3]

As of #1403 inline asm is now supported and stable on all targets supported by cg_clif.

[repi]

awesome!

did a quick test with building our codebase with this and did fail on wasmtime-runtime using inline asm:

error: asm! and global_asm! sym operands are not yet supported
   --> /home/repi/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasmtime-runtime-14.0.2/src/libcalls.rs:156:5
    |
156 |     wasmtime_environ::foreach_builtin_function!(libcall);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this error originates in the macro `std::arch::global_asm` which comes from the expansion of the macro `wasmtime_environ::foreach_builtin_function` (in Nightly builds, run with -Z macro-backtrace for more info)

related to this note?

For global asm (#1351, but doesn't work when the function is made private to the codegen unit)

or maybe this was not part of the new deployed rustup component?

[bjorn3]

related to this note?

Correct. So far I had only checked wasmtime with unstable features enabled (as is the default for building it using ./y.sh in this repo), but not with unstable features disabled (as is the case for the rustc-codegen-cranelift-preview rustup component) With unstable features enabled the entire wasmtime test suite passes with the exception of a couple of tests that need panic=unwind.

[repi]

ah good to know, and fantastic that the full test suite passes!