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Rollup merge of rust-lang#131258 - taiki-e:s390x-stabilize-asm, r=Ama…
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Stabilize s390x inline assembly

This stabilizes inline assembly for s390x (SystemZ).

Corresponding reference PR: rust-lang/reference#1643

---

From the requirements of stabilization mentioned in rust-lang#93335

> Each architecture needs to be reviewed before stabilization:

> - It must have clobber_abi.

Done in rust-lang#130630.

> - It must be possible to clobber every register that is normally clobbered by a function call.

Done in the PR that added support for clobber_abi.

> - Generally review that the exposed register classes make sense.

The followings can be used as input/output:

- `reg` (`r[0-10]`, `r[12-14]`): General-purpose register

- `reg_addr` (`r[1-10]`, `r[12-14]`): General-purpose register except `r0` which is evaluated as zero in an address context

  This class is needed because `r0`, which may be allocated when using the `reg` class, cannot be used as a register in certain contexts. This is identical to the `a` constraint in LLVM and GCC. See rust-lang#119431 for details.

- `freg` (`f[0-15]`): Floating-point register

The followings are clobber-only:

- `vreg` (`v[0-31]`): Vector register

  Technically `vreg` should be able to accept `#[repr(simd)]` types as input/output if the unstable `vector` target feature added is enabled, but `core::arch` has no s390x vector type and both `#[repr(simd)]` and `core::simd` are unstable. Everything related is unstable, so the fact that this is currently a clobber-only should not be considered a stabilization blocker. (rust-lang#130869 tracks unstable stuff here)

- `areg` (`a[2-15]`): Access register

All of the above register classes except `reg_addr` are needed for `clobber_abi`.

The followings cannot be used as operands for inline asm (see also [getReservedRegs](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/SystemZ/SystemZRegisterInfo.cpp#L258-L282) and [SystemZELFRegisters](https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/SystemZ/SystemZRegisterInfo.h#L107-L128) in LLVM):

- `r11`: frame pointer
- `r15`: stack pointer
- `a0`, `a1`: Reserved for system use
- `c[0-15]` (control register)  Reserved by the kernel

Although not listed in the above requirements, `preserves_flags` is implemented in rust-lang#111331.

---

cc `@uweigand`

r? `@Amanieu`

`@rustbot` label +O-SystemZ +A-inline-assembly
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@matthiaskrgr
matthiaskrgr authored Nov 9, 2024
2 parents b026d85 + ab62a35 commit 0fff0e6
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1 change: 1 addition & 0 deletions compiler/rustc_ast_lowering/src/asm.rs
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Expand Up @@ -48,6 +48,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
| asm::InlineAsmArch::RiscV32
| asm::InlineAsmArch::RiscV64
| asm::InlineAsmArch::LoongArch64
| asm::InlineAsmArch::S390x
);
if !is_stable && !self.tcx.features().asm_experimental_arch() {
feature_err(
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21 changes: 2 additions & 19 deletions src/doc/unstable-book/src/language-features/asm-experimental-arch.md
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Expand Up @@ -18,7 +18,6 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
- MSP430
- M68k
- CSKY
- s390x
- Arm64EC
- SPARC

Expand Down Expand Up @@ -52,11 +51,6 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
| M68k | `reg_addr` | `a[0-3]` | `a` |
| CSKY | `reg` | `r[0-31]` | `r` |
| CSKY | `freg` | `f[0-31]` | `f` |
| s390x | `reg` | `r[0-10]`, `r[12-14]` | `r` |
| s390x | `reg_addr` | `r[1-10]`, `r[12-14]` | `a` |
| s390x | `freg` | `f[0-15]` | `f` |
| s390x | `vreg` | `v[0-31]` | Only clobbers |
| s390x | `areg` | `a[2-15]` | Only clobbers |
| SPARC | `reg` | `r[2-29]` | `r` |
| SPARC | `yreg` | `y` | Only clobbers |
| Arm64EC | `reg` | `x[0-12]`, `x[15-22]`, `x[25-27]`, `x30` | `r` |
Expand Down Expand Up @@ -96,10 +90,6 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
| M68k | `reg_data` | None | `i8`, `i16`, `i32` |
| CSKY | `reg` | None | `i8`, `i16`, `i32` |
| CSKY | `freg` | None | `f32`, |
| s390x | `reg`, `reg_addr` | None | `i8`, `i16`, `i32`, `i64` |
| s390x | `freg` | None | `f32`, `f64` |
| s390x | `vreg` | N/A | Only clobbers |
| s390x | `areg` | N/A | Only clobbers |
| SPARC | `reg` | None | `i8`, `i16`, `i32`, `i64` (SPARC64 only) |
| SPARC | `yreg` | N/A | Only clobbers |
| Arm64EC | `reg` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |
Expand Down Expand Up @@ -159,8 +149,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect

| Architecture | Unsupported register | Reason |
| ------------ | --------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| All | `sp`, `r15` (s390x), `r14`/`o6` (SPARC) | The stack pointer must be restored to its original value at the end of an asm code block. |
| All | `fr` (Hexagon), `fp` (PowerPC), `$fp` (MIPS), `Y` (AVR), `r4` (MSP430), `a6` (M68k), `r11` (s390x), `r30`/`i6` (SPARC), `x29` (Arm64EC) | The frame pointer cannot be used as an input or output. |
| All | `sp`, `r14`/`o6` (SPARC) | The stack pointer must be restored to its original value at the end of an asm code block. |
| All | `fr` (Hexagon), `fp` (PowerPC), `$fp` (MIPS), `Y` (AVR), `r4` (MSP430), `a6` (M68k), `r30`/`i6` (SPARC), `x29` (Arm64EC) | The frame pointer cannot be used as an input or output. |
| All | `r19` (Hexagon), `r29` (PowerPC), `r30` (PowerPC), `x19` (Arm64EC) | These are used internally by LLVM as "base pointer" for functions with complex stack frames. |
| MIPS | `$0` or `$zero` | This is a constant zero register which can't be modified. |
| MIPS | `$1` or `$at` | Reserved for assembler. |
Expand All @@ -181,8 +171,6 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
| CSKY | `r15` | This is the link register. |
| CSKY | `r[26-30]` | Reserved by its ABI. |
| CSKY | `r31` | This is the TLS register. |
| s390x | `c[0-15]` | Reserved by the kernel. |
| s390x | `a[0-1]` | Reserved for system use. |
| SPARC | `r0`/`g0` | This is always zero and cannot be used as inputs or outputs. |
| SPARC | `r1`/`g1` | Used internally by LLVM. |
| SPARC | `r5`/`g5` | Reserved for system. (SPARC32 only) |
Expand All @@ -206,9 +194,6 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
| PowerPC | `reg` | None | `0` | None |
| PowerPC | `reg_nonzero` | None | `3` | None |
| PowerPC | `freg` | None | `0` | None |
| s390x | `reg` | None | `%r0` | None |
| s390x | `reg_addr` | None | `%r1` | None |
| s390x | `freg` | None | `%f0` | None |
| SPARC | `reg` | None | `%o0` | None |
| CSKY | `reg` | None | `r0` | None |
| CSKY | `freg` | None | `f0` | None |
Expand All @@ -232,8 +217,6 @@ These flags registers must be restored upon exiting the asm block if the `preser
- The status register `r2`.
- M68k
- The condition code register `ccr`.
- s390x
- The condition code register `cc`.
- SPARC
- Integer condition codes (`icc` and `xcc`)
- Floating-point condition codes (`fcc[0-3]`)
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2 changes: 1 addition & 1 deletion tests/assembly/asm/s390x-types.rs
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Expand Up @@ -4,7 +4,7 @@
//@[s390x] needs-llvm-components: systemz
//@ compile-flags: -Zmerge-functions=disabled

#![feature(no_core, lang_items, rustc_attrs, repr_simd, asm_experimental_arch)]
#![feature(no_core, lang_items, rustc_attrs, repr_simd)]
#![crate_type = "rlib"]
#![no_core]
#![allow(asm_sub_register, non_camel_case_types)]
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2 changes: 1 addition & 1 deletion tests/codegen/asm/s390x-clobbers.rs
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Expand Up @@ -3,7 +3,7 @@
//@[s390x] needs-llvm-components: systemz

#![crate_type = "rlib"]
#![feature(no_core, rustc_attrs, lang_items, asm_experimental_arch)]
#![feature(no_core, rustc_attrs, lang_items)]
#![no_core]

#[lang = "sized"]
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