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rustc_target: add known safe s390x target features #127506

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Jul 22, 2024
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rustc_target: add known safe s390x target features #127506

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efcf35e
rustc_target: add known safe s390x target features
liushuyu Jul 9, 2024
c940d52
rustc_target: fix UI tests for s390x
liushuyu Jul 9, 2024
366bc86
rustc_codegen_ssa: add s390x_target_feature symbol
liushuyu Jul 9, 2024
01e6e60
rustc_codegen_llvm: properly passing backchain attribute to LLVM ...
liushuyu Jul 10, 2024
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14 changes: 14 additions & 0 deletions compiler/rustc_codegen_llvm/src/attributes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,17 @@ fn stackprotector_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
Some(sspattr.create_attr(cx.llcx))
}

fn backchain_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
if cx.sess().target.arch != "s390x" {
return None;
}

let requested_features = cx.sess().opts.cg.target_feature.split(',');
let found_positive = requested_features.clone().any(|r| r == "+backchain");

if found_positive { Some(llvm::CreateAttrString(cx.llcx, "backchain")) } else { None }
}

pub fn target_cpu_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> &'ll Attribute {
let target_cpu = llvm_util::target_cpu(cx.tcx.sess);
llvm::CreateAttrStringValue(cx.llcx, "target-cpu", target_cpu)
Expand Down Expand Up @@ -447,6 +458,9 @@ pub fn from_fn_attrs<'ll, 'tcx>(
if let Some(align) = codegen_fn_attrs.alignment {
llvm::set_alignment(llfn, align);
}
if let Some(backchain) = backchain_attr(cx) {
to_add.push(backchain);
}
to_add.extend(sanitize_attrs(cx, codegen_fn_attrs.no_sanitize));
to_add.extend(patchable_function_entry_attrs(cx, codegen_fn_attrs.patchable_function_entry));

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14 changes: 13 additions & 1 deletion compiler/rustc_codegen_llvm/src/llvm_util.rs
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Expand Up @@ -14,7 +14,7 @@ use rustc_session::config::{PrintKind, PrintRequest};
use rustc_session::Session;
use rustc_span::symbol::Symbol;
use rustc_target::spec::{MergeFunctions, PanicStrategy};
use rustc_target::target_features::RUSTC_SPECIFIC_FEATURES;
use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES};

use std::ffi::{c_char, c_void, CStr, CString};
use std::fmt::Write;
Expand Down Expand Up @@ -321,6 +321,10 @@ pub fn target_features(sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
}
})
.filter(|feature| {
// skip checking special features, as LLVM may not understands them
if RUSTC_SPECIAL_FEATURES.contains(feature) {
return true;
}
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This makes it so that cfg!(target_feature = "backchain") will always be true, even if it is not enabled. Is that the intended behavior? It seems very odd.

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No, this is to skip checking if LLVM supports this attribute. The logic for adding this attribute is somewhere else.
If you are unconvinced, check out this Godbolt playground: https://godbolt.org/z/77hrrsbo1.

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I am convinced that the logic is wrong, see #129927.

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Also, I have no idea what I am supposed to look at in this Godbolt.^^ I know nothing about s390x or backchain, I am just noticing odd things in the rustc source code.

// check that all features in a given smallvec are enabled
for llvm_feature in to_llvm_features(sess, feature) {
let cstr = SmallCStr::new(llvm_feature);
Expand Down Expand Up @@ -546,6 +550,7 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str

// -Ctarget-features
let supported_features = sess.target.supported_target_features();
let (llvm_major, _, _) = get_version();
let mut featsmap = FxHashMap::default();
let feats = sess
.opts
Expand Down Expand Up @@ -604,6 +609,13 @@ pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<Str
if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
return None;
}

// if the target-feature is "backchain" and LLVM version is greater than 18
// then we also need to add "+backchain" to the target-features attribute.
// otherwise, we will only add the naked `backchain` attribute to the attribute-group.
if feature == "backchain" && llvm_major < 18 {
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This entire RUSTC_SPECIAL_FEATURES is a temporary hack we can drop when we start requiring LLVM 18, right? Please file an issue to track this cleanup.

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This entire RUSTC_SPECIAL_FEATURES is a temporary hack we can drop when we start requiring LLVM 18, right? Please file an issue to track this cleanup.

Yes, this is due to older LLVM does not support adding this attribute to the target-features attribute.

return None;
}
// ... otherwise though we run through `to_llvm_features` when
// passing requests down to LLVM. This means that all in-language
// features also work on the command line instead of having two
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_codegen_ssa/src/target_features.rs
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Expand Up @@ -82,6 +82,7 @@ pub fn from_target_feature(
Some(sym::prfchw_target_feature) => rust_features.prfchw_target_feature,
Some(sym::x86_amx_intrinsics) => rust_features.x86_amx_intrinsics,
Some(sym::xop_target_feature) => rust_features.xop_target_feature,
Some(sym::s390x_target_feature) => rust_features.s390x_target_feature,
Some(name) => bug!("unknown target feature gate {}", name),
None => true,
};
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1 change: 1 addition & 0 deletions compiler/rustc_feature/src/unstable.rs
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Expand Up @@ -312,6 +312,7 @@ declare_features! (
(unstable, prfchw_target_feature, "1.78.0", Some(44839)),
(unstable, riscv_target_feature, "1.45.0", Some(44839)),
(unstable, rtm_target_feature, "1.35.0", Some(44839)),
(unstable, s390x_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
(unstable, sse4a_target_feature, "1.27.0", Some(44839)),
(unstable, tbm_target_feature, "1.27.0", Some(44839)),
(unstable, wasm_target_feature, "1.30.0", Some(44839)),
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_span/src/symbol.rs
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Expand Up @@ -1689,6 +1689,7 @@ symbols! {
rvalue_static_promotion,
rwpi,
s,
s390x_target_feature,
safety,
sanitize,
sanitizer_cfi_generalize_pointers,
Expand Down
12 changes: 12 additions & 0 deletions compiler/rustc_target/src/target_features.rs
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Expand Up @@ -4,6 +4,9 @@ use rustc_span::symbol::Symbol;
/// Features that control behaviour of rustc, rather than the codegen.
pub const RUSTC_SPECIFIC_FEATURES: &[&str] = &["crt-static"];

/// Features that require special handling when passing to LLVM.
pub const RUSTC_SPECIAL_FEATURES: &[&str] = &["backchain"];

/// Stability information for target features.
#[derive(Debug, Clone, Copy)]
pub enum Stability {
Expand Down Expand Up @@ -397,6 +400,13 @@ const LOONGARCH_ALLOWED_FEATURES: &[(&str, Stability)] = &[
// tidy-alphabetical-end
];

const IBMZ_ALLOWED_FEATURES: &[(&str, Stability)] = &[
// tidy-alphabetical-start
("backchain", Unstable(sym::s390x_target_feature)),
("vector", Unstable(sym::s390x_target_feature)),
// tidy-alphabetical-end
];

/// When rustdoc is running, provide a list of all known features so that all their respective
/// primitives may be documented.
///
Expand All @@ -414,6 +424,7 @@ pub fn all_known_features() -> impl Iterator<Item = (&'static str, Stability)> {
.chain(BPF_ALLOWED_FEATURES.iter())
.chain(CSKY_ALLOWED_FEATURES)
.chain(LOONGARCH_ALLOWED_FEATURES)
.chain(IBMZ_ALLOWED_FEATURES)
.cloned()
}

Expand All @@ -431,6 +442,7 @@ impl super::spec::Target {
"bpf" => BPF_ALLOWED_FEATURES,
"csky" => CSKY_ALLOWED_FEATURES,
"loongarch64" => LOONGARCH_ALLOWED_FEATURES,
"s390x" => IBMZ_ALLOWED_FEATURES,
_ => &[],
}
}
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/check-cfg/mix.stderr
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Expand Up @@ -251,7 +251,7 @@ warning: unexpected `cfg` condition value: `zebra`
LL | cfg!(target_feature = "zebra");
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 197 more
= note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 199 more
= note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration

warning: 27 warnings emitted
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/check-cfg/well-known-values.stderr
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Expand Up @@ -165,7 +165,7 @@ warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
LL | target_feature = "_UNEXPECTED_VALUE",
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, `avx512vpopcntdq`, `avxifma`, `avxneconvert`, `avxvnni`, `avxvnniint16`, `avxvnniint8`, `bf16`, `bmi1`, `bmi2`, `bti`, `bulk-memory`, `c`, `cache`, `cmpxchg16b`, `crc`, `crt-static`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `fcma`, `fdivdu`, `fhm`, `flagm`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `lor`, `lse`, `lsx`, `lvz`, `lzcnt`, `m`, `mclass`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sign-ext`, `simd128`, `sm4`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `sve`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `tbm`, `thumb-mode`, `thumb2`, `tme`, `trust`, `trustzone`, `ual`, `unaligned-scalar-mem`, `v`, `v5te`, `v6`, `v6k`, `v6t2`, `v7`, `v8`, `v8.1a`, `v8.2a`, `v8.3a`, `v8.4a`, `v8.5a`, `v8.6a`, `v8.7a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zba`, `zbb`, `zbc`, `zbkb`, `zbkc`, `zbkx`, `zbs`, `zdinx`, `zfh`, `zfhmin`, `zfinx`, `zhinx`, `zhinxmin`, `zk`, `zkn`, `zknd`, `zkne`, `zknh`, `zkr`, `zks`, `zksed`, `zksh`, and `zkt`
= note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, `avx512vpopcntdq`, `avxifma`, `avxneconvert`, `avxvnni`, `avxvnniint16`, `avxvnniint8`, `backchain`, `bf16`, `bmi1`, `bmi2`, `bti`, `bulk-memory`, `c`, `cache`, `cmpxchg16b`, `crc`, `crt-static`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `fcma`, `fdivdu`, `fhm`, `flagm`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `lor`, `lse`, `lsx`, `lvz`, `lzcnt`, `m`, `mclass`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sign-ext`, `simd128`, `sm4`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `sve`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `tbm`, `thumb-mode`, `thumb2`, `tme`, `trust`, `trustzone`, `ual`, `unaligned-scalar-mem`, `v`, `v5te`, `v6`, `v6k`, `v6t2`, `v7`, `v8`, `v8.1a`, `v8.2a`, `v8.3a`, `v8.4a`, `v8.5a`, `v8.6a`, `v8.7a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vector`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zba`, `zbb`, `zbc`, `zbkb`, `zbkc`, `zbkx`, `zbs`, `zdinx`, `zfh`, `zfhmin`, `zfinx`, `zhinx`, `zhinxmin`, `zk`, `zkn`, `zknd`, `zkne`, `zknh`, `zkr`, `zks`, `zksed`, `zksh`, and `zkt`
= note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
Expand Down
1 change: 1 addition & 0 deletions tests/ui/target-feature/gate.rs
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Expand Up @@ -21,6 +21,7 @@
// gate-test-loongarch_target_feature
// gate-test-lahfsahf_target_feature
// gate-test-prfchw_target_feature
// gate-test-s390x_target_feature

#[target_feature(enable = "avx512bw")]
//~^ ERROR: currently unstable
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/target-feature/gate.stderr
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@@ -1,5 +1,5 @@
error[E0658]: the target feature `avx512bw` is currently unstable
--> $DIR/gate.rs:25:18
--> $DIR/gate.rs:26:18
|
LL | #[target_feature(enable = "avx512bw")]
| ^^^^^^^^^^^^^^^^^^^
Expand Down
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