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forbid toggling x87 and fpregs on hard-float targets
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RalfJung committed Nov 28, 2024
1 parent c1caaa3 commit 41ab0fc
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Showing 21 changed files with 129 additions and 10 deletions.
1 change: 1 addition & 0 deletions compiler/rustc_feature/src/unstable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -342,6 +342,7 @@ declare_features! (
(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)),
(unstable, x87_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
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1 change: 1 addition & 0 deletions compiler/rustc_span/src/symbol.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2179,6 +2179,7 @@ symbols! {
writeln_macro,
x86_amx_intrinsics,
x87_reg,
x87_target_feature,
xer,
xmm_reg,
xop_target_feature,
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12 changes: 12 additions & 0 deletions compiler/rustc_target/src/spec/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2592,6 +2592,18 @@ impl TargetOptions {
.collect();
}
}

pub(crate) fn has_feature(&self, search_feature: &str) -> bool {
self.features.split(',').any(|f| {
if let Some(f) = f.strip_prefix('+')
&& f == search_feature
{
true
} else {
false
}
})
}
}

impl Default for TargetOptions {
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36 changes: 34 additions & 2 deletions compiler/rustc_target/src/target_features.rs
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@ pub enum Stability<AllowToggle> {
/// This target feature is unstable. It is only present in `#[cfg(target_feature)]` on
/// nightly and using it in `#[target_feature]` requires enabling the given nightly feature.
Unstable {
/// This must be a *language* feature, or else rustc will ICE when reporting a missing
/// feature gate!
nightly_feature: Symbol,
/// See `Stable::allow_toggle` comment above.
allow_toggle: AllowToggle,
Expand Down Expand Up @@ -168,6 +170,22 @@ const ARM_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
("dotprod", unstable(sym::arm_target_feature), &["neon"]),
("dsp", unstable(sym::arm_target_feature), &[]),
("fp-armv8", unstable(sym::arm_target_feature), &["vfp4"]),
(
"fpregs",
Stability::Unstable {
nightly_feature: sym::arm_target_feature,
allow_toggle: |target: &Target| {
// Only allow toggling this if the target has `soft-float` set. With `soft-float`,
// `fpregs` isn't needed so changing it cannot affect the ABI.
if target.has_feature("soft-float") {
Ok(())
} else {
Err("unsound on hard-float targets because it changes float ABI")
}
},
},
&[],
),
("i8mm", unstable(sym::arm_target_feature), &["neon"]),
("mclass", unstable(sym::arm_target_feature), &[]),
("neon", unstable(sym::arm_target_feature), &["vfp3"]),
Expand All @@ -191,7 +209,6 @@ const ARM_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
("vfp4", unstable(sym::arm_target_feature), &["vfp3"]),
("virtualization", unstable(sym::arm_target_feature), &[]),
// tidy-alphabetical-end
// FIXME: need to also forbid turning off `fpregs` on hardfloat targets
];

const AARCH64_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
Expand Down Expand Up @@ -450,13 +467,28 @@ const X86_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
("tbm", unstable(sym::tbm_target_feature), &[]),
("vaes", unstable(sym::avx512_target_feature), &["avx2", "aes"]),
("vpclmulqdq", unstable(sym::avx512_target_feature), &["avx", "pclmulqdq"]),
(
"x87",
Stability::Unstable {
nightly_feature: sym::x87_target_feature,
allow_toggle: |target: &Target| {
// Only allow toggling this if the target has `soft-float` set. With `soft-float`,
// `fpregs` isn't needed so changing it cannot affect the ABI.
if target.has_feature("soft-float") {
Ok(())
} else {
Err("unsound on hard-float targets because it changes float ABI")
}
},
},
&[],
),
("xop", unstable(sym::xop_target_feature), &[/*"fma4", */ "avx", "sse4a"]),
("xsave", STABLE, &[]),
("xsavec", STABLE, &["xsave"]),
("xsaveopt", STABLE, &["xsave"]),
("xsaves", STABLE, &["xsave"]),
// tidy-alphabetical-end
// FIXME: need to also forbid turning off `x87` on hardfloat targets
];

const HEXAGON_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/check-cfg/mix.stderr
Original file line number Diff line number Diff line change
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 252 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 254 more
= note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration

warning: 27 warnings emitted
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2 changes: 1 addition & 1 deletion tests/ui/check-cfg/well-known-values.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -174,7 +174,7 @@ 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`, `backchain`, `bf16`, `bmi1`, `bmi2`, `bti`, `bulk-memory`, `c`, `cache`, `cmpxchg16b`, `crc`, `crt-static`, `cssc`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `ecv`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `faminmax`, `fcma`, `fdivdu`, `fhm`, `flagm`, `flagm2`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fp8`, `fp8dot2`, `fp8dot4`, `fp8fma`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `hbc`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `leoncasa`, `lor`, `lse`, `lse128`, `lse2`, `lsx`, `lut`, `lvz`, `lzcnt`, `m`, `mclass`, `mops`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `partword-atomics`, `pauth-lr`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `quadword-atomics`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rcpc3`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `reserve-x18`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sha512`, `sign-ext`, `simd128`, `sm3`, `sm4`, `sme`, `sme-b16b16`, `sme-f16f16`, `sme-f64f64`, `sme-f8f16`, `sme-f8f32`, `sme-fa64`, `sme-i16i64`, `sme-lutv2`, `sme2`, `sme2p1`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `ssve-fp8dot2`, `ssve-fp8dot4`, `ssve-fp8fma`, `sve`, `sve-b16b16`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `sve2p1`, `tail-call`, `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`, `v8.8a`, `v8.9a`, `v8plus`, `v9`, `v9.1a`, `v9.2a`, `v9.3a`, `v9.4a`, `v9.5a`, `v9a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vector`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `wfxt`, `wide-arithmetic`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zaamo`, `zabha`, `zalrsc`, `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`, `cssc`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `ecv`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `faminmax`, `fcma`, `fdivdu`, `fhm`, `flagm`, `flagm2`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fp8`, `fp8dot2`, `fp8dot4`, `fp8fma`, `fpregs`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `hbc`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `leoncasa`, `lor`, `lse`, `lse128`, `lse2`, `lsx`, `lut`, `lvz`, `lzcnt`, `m`, `mclass`, `mops`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `partword-atomics`, `pauth-lr`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `quadword-atomics`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rcpc3`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `reserve-x18`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sha512`, `sign-ext`, `simd128`, `sm3`, `sm4`, `sme`, `sme-b16b16`, `sme-f16f16`, `sme-f64f64`, `sme-f8f16`, `sme-f8f32`, `sme-fa64`, `sme-i16i64`, `sme-lutv2`, `sme2`, `sme2p1`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `ssve-fp8dot2`, `ssve-fp8dot4`, `ssve-fp8fma`, `sve`, `sve-b16b16`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `sve2p1`, `tail-call`, `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`, `v8.8a`, `v8.9a`, `v8plus`, `v9`, `v9.1a`, `v9.2a`, `v9.3a`, `v9.4a`, `v9.5a`, `v9a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vector`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `wfxt`, `wide-arithmetic`, `x87`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zaamo`, `zabha`, `zalrsc`, `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
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
//@ compile-flags: --target=x86_64-unknown-none --crate-type=lib
//@ needs-llvm-components: x86
//@ build-pass
#![feature(no_core, lang_items, x87_target_feature)]
#![no_core]

#[lang = "sized"]
pub trait Sized {}

#[target_feature(enable = "x87")]
pub unsafe fn my_fun() {}
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
//@ compile-flags: --target=x86_64-unknown-none --crate-type=lib
//@ needs-llvm-components: x86
//@ compile-flags: -Ctarget-feature=-x87
//@ build-pass
#![feature(no_core, lang_items)]
#![no_core]

#[lang = "sized"]
pub trait Sized {}
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
warning: unstable feature specified for `-Ctarget-feature`: `x87`
|
= note: this feature is not stably supported; its behavior can change in the future

warning: 1 warning emitted

Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
//@ needs-llvm-components: x86
#![feature(no_core, lang_items)]
#![no_core]

#[lang = "sized"]
pub trait Sized {}

#[target_feature(enable = "x87")]
//~^ERROR: cannot be toggled with
pub unsafe fn my_fun() {}
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
error: target feature `x87` cannot be toggled with `#[target_feature]`: unsound on hard-float targets because it changes float ABI
--> $DIR/forbidden-hardfloat-target-feature-attribute.rs:9:18
|
LL | #[target_feature(enable = "x87")]
| ^^^^^^^^^^^^^^

error: aborting due to 1 previous error

14 changes: 14 additions & 0 deletions tests/ui/target-feature/forbidden-hardfloat-target-feature-cfg.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
//@ needs-llvm-components: x86
//@ check-pass
#![feature(no_core, lang_items)]
#![no_core]
#![allow(unexpected_cfgs)]

#[lang = "sized"]
pub trait Sized {}

// The compile_error macro does not exist, so if the `cfg` evaluates to `true` this
// complains about the missing macro rather than showing the error... but that's good enough.
#[cfg(not(target_feature = "x87"))]
compile_error!("the x87 feature *should* be exposed in `cfg`");
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
//@ needs-llvm-components: x86
//@ compile-flags: -Ctarget-feature=-x87
// For now this is just a warning.
//@ build-pass
#![feature(no_core, lang_items)]
#![no_core]

#[lang = "sized"]
pub trait Sized {}
Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
warning: target feature `x87` cannot be toggled with `-Ctarget-feature`: unsound on hard-float targets because it changes float ABI
|
= note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>

warning: 1 warning emitted

Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
//@ needs-llvm-components: x86
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]

#[lang = "sized"]
Expand Down
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: target feature `soft-float` cannot be toggled with `#[target_feature]`: unsound because it changes float ABI
--> $DIR/forbidden-target-feature-attribute.rs:10:18
--> $DIR/forbidden-target-feature-attribute.rs:9:18
|
LL | #[target_feature(enable = "soft-float")]
| ^^^^^^^^^^^^^^^^^^^^^
Expand Down
1 change: 0 additions & 1 deletion tests/ui/target-feature/forbidden-target-feature-cfg.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@
//@ needs-llvm-components: x86
//@ check-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]
#![allow(unexpected_cfgs)]

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@
// For now this is just a warning.
//@ build-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]

#[lang = "sized"]
Expand Down
1 change: 0 additions & 1 deletion tests/ui/target-feature/forbidden-target-feature-flag.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@
// For now this is just a warning.
//@ build-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]

#[lang = "sized"]
Expand Down
1 change: 1 addition & 0 deletions tests/ui/target-feature/gate.rs
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
// gate-test-prfchw_target_feature
// gate-test-s390x_target_feature
// gate-test-sparc_target_feature
// gate-test-x87_target_feature

#[target_feature(enable = "avx512bw")]
//~^ ERROR: currently unstable
Expand Down
2 changes: 1 addition & 1 deletion tests/ui/target-feature/gate.stderr
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error[E0658]: the target feature `avx512bw` is currently unstable
--> $DIR/gate.rs:28:18
--> $DIR/gate.rs:29:18
|
LL | #[target_feature(enable = "avx512bw")]
| ^^^^^^^^^^^^^^^^^^^
Expand Down

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