This tracks the status of s390x vector facilities support in rustc and standard libraries.

• ABI support
  • support z13 vector ABI: done in Support s390x z13 vector ABI #131586
    

    rust/compiler/rustc_target/src/abi/call/s390x.rs

    Lines 1 to 2 in 58420a0

    	// FIXME: The assumes we're using the non-vector ABI, i.e., compiling
    	// for a pre-z13 machine or using -mno-vx.

  • remove explicit disabling of the vector feature (blocked on the above FIXME): done in Support s390x z13 vector ABI #131586
    

    rust/compiler/rustc_target/src/spec/targets/s390x_unknown_linux_gnu.rs

    Lines 9 to 11 in 58420a0

    	// FIXME: The ABI implementation in abi/call/s390x.rs is for now hard-coded to assume the no-vector
    	// ABI. Pass the -vector feature string to LLVM to respect this assumption.
    	base.features = "-vector".into();

• target_feature support
  • support nightly-only cfg(target_feature = "vector") and unstable target_feature(enable = "vector") (under feature(s390x_target_feature)): done in rustc_target: add known safe s390x target features #127506
  • support other vector facility-related target features: vector-enhancements-1, vector-enhancements-2, etc. (see also Missing support for target features on s390x #88937); done in add more s390x target features #135630
  • stabilize target_feature = "vector" (and other vector-related target features if available)
    At least blocked until ABI support done UPDATE: ABI support done
    And may be more things are needed given the precedent of postponed stabilization of vector features in RISC-V.
• asm support
  • support clobber-only vector registers: done in Support clobber_abi and vector/access registers (clobber-only) in s390x inline assembly #130630
  • stabilize feature(asm_experimental_arch) on s390x: done in Stabilize s390x inline assembly #131258
  • support #[repr(simd)] types in input/output of asm (i.e., fully support vector registers) under feature(asm_experimental_reg): pending in Support input/output in vector registers of s390x inline assembly (under asm_experimental_reg feature) #131664
    Both LLVM and GCC do not document v constraint, but actually seem to be supported.
    Blocked until ABI support done. UPDATE: ABI support done
  • stabilize feature(asm_experimental_reg) for s390x vector registers (Tracking Issue for asm_experimental_reg #133416)
• core_arch support (tracking issue: Tracking Issue for stdarch_s390x #135681)
  • add unstable vector intrinsics to core::arch::s390x: mostly done s390x vector facilities support #130869 (comment)
    Blocked until ABI support done. UPDATE: ABI support done
• std_detect support (tracking issue: Tracking Issue for stdarch_s390x_feature_detection #135413)
  • support unstable is_s390x_feature_detected!("vector"): done in add is_s390x_feature_detected stdarch#1699

@rustbot label +O-SystemZ