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forbid toggling x87 and fpregs on hard-float targets

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This commit is contained in:
Ralf Jung 2024-11-16 10:26:46 +01:00
parent 2d887a5c5c
commit d6ddc73dae
20 changed files with 129 additions and 8 deletions
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1
compiler/rustc_feature/src/unstable.rs
View file

@ -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.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!

1
compiler/rustc_span/src/symbol.rs
View file

@ -2200,6 +2200,7 @@ symbols! {
writeln_macro,
x86_amx_intrinsics,
x87_reg,
x87_target_feature,
xer,
xmm_reg,
xop_target_feature,

12
compiler/rustc_target/src/spec/mod.rs
View file

@ -2603,6 +2603,18 @@ 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 {

36
compiler/rustc_target/src/target_features.rs
View file

@ -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,
@ -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"]),
@ -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)] = &[
@ -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)] = &[

2
tests/ui/check-cfg/target_feature.stderr
View file

@ -98,6 +98,7 @@ LL | cfg!(target_feature = "_UNEXPECTED_VALUE");
`fp8dot2`
`fp8dot4`
`fp8fma`
`fpregs`
`fpuv2_df`
`fpuv2_sf`
`fpuv3_df`
@ -261,6 +262,7 @@ LL | cfg!(target_feature = "_UNEXPECTED_VALUE");
`vsx`
`wfxt`
`wide-arithmetic`
`x87`
`xop`
`xsave`
`xsavec`

11
tests/ui/target-feature/allowed-softfloat-target-feature-attribute.rs Normal file
View file

@ -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() {}

9
tests/ui/target-feature/allowed-softfloat-target-feature-flag-disable.rs Normal file
View file

@ -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 {}

6
tests/ui/target-feature/allowed-softfloat-target-feature-flag-disable.stderr Normal file
View file

@ -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

11
tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs Normal file
View file

@ -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() {}

8
tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr Normal file
View file

@ -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
tests/ui/target-feature/forbidden-hardfloat-target-feature-cfg.rs Normal file
View file

@ -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`");

10
tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.rs Normal file
View file

@ -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 {}

7
tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.stderr Normal file
View file

@ -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

1
tests/ui/target-feature/forbidden-target-feature-attribute.rs
View file

@ -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"]

2
tests/ui/target-feature/forbidden-target-feature-attribute.stderr
View file

@ -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")]
| ^^^^^^^^^^^^^^^^^^^^^

1
tests/ui/target-feature/forbidden-target-feature-cfg.rs
View file

@ -2,7 +2,6 @@
//@ needs-llvm-components: x86
//@ check-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]
#![allow(unexpected_cfgs)]

1
tests/ui/target-feature/forbidden-target-feature-flag-disable.rs
View file

@ -4,7 +4,6 @@
// For now this is just a warning.
//@ build-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]
#[lang = "sized"]

1
tests/ui/target-feature/forbidden-target-feature-flag.rs
View file

@ -4,7 +4,6 @@
// For now this is just a warning.
//@ build-pass
#![feature(no_core, lang_items)]
#![no_std]
#![no_core]
#[lang = "sized"]

1
tests/ui/target-feature/gate.rs
View file

@ -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

2
tests/ui/target-feature/gate.stderr
View file

@ -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")]
| ^^^^^^^^^^^^^^^^^^^