-
Notifications
You must be signed in to change notification settings - Fork 12.7k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Emit warning when calling/declaring functions with unavailable vectors.
On some architectures, vector types may have a different ABI depending on whether the relevant target features are enabled. (The ABI when the feature is disabled is often not specified, but LLVM implements some de-facto ABI.) As discussed in rust-lang/lang-team#235, this turns out to very easily lead to unsound code. This commit makes it a post-monomorphization future-incompat warning to declare or call functions using those vector types in a context in which the corresponding target features are disabled, if using an ABI for which the difference is relevant. This ensures that these functions are always called with a consistent ABI. See the [nomination comment](#127731 (comment)) for more discussion. Part of #116558
- Loading branch information
Showing
12 changed files
with
519 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,169 @@ | ||
| //! This module ensures that if a function's ABI requires a particular target feature, | ||
| //! that target feature is enabled both on the callee and all callers. | ||
| use rustc_hir::CRATE_HIR_ID; | ||
| use rustc_hir::def::DefKind; | ||
| use rustc_middle::query::Providers; | ||
| use rustc_middle::ty::inherent::*; | ||
| use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt}; | ||
| use rustc_session::lint::builtin::ABI_UNSUPPORTED_VECTOR_TYPES; | ||
| use rustc_span::def_id::DefId; | ||
| use rustc_span::{DUMMY_SP, Span, Symbol}; | ||
| use rustc_target::abi::call::{FnAbi, PassMode}; | ||
| use rustc_target::abi::{BackendRepr, RegKind}; | ||
|
|
||
| use crate::errors::{AbiErrorDisabledVectorTypeCall, AbiErrorDisabledVectorTypeDef}; | ||
|
|
||
| fn uses_vector_registers(mode: &PassMode, repr: &BackendRepr) -> bool { | ||
| match mode { | ||
| PassMode::Ignore | PassMode::Indirect { .. } => false, | ||
| PassMode::Cast { pad_i32: _, cast } => { | ||
| cast.prefix.iter().any(|r| r.is_some_and(|x| x.kind == RegKind::Vector)) | ||
| || cast.rest.unit.kind == RegKind::Vector | ||
| } | ||
| PassMode::Direct(..) | PassMode::Pair(..) => matches!(repr, BackendRepr::Vector { .. }), | ||
| } | ||
| } | ||
|
|
||
| fn do_check_abi<'tcx>( | ||
| tcx: TyCtxt<'tcx>, | ||
| abi: &FnAbi<'tcx, Ty<'tcx>>, | ||
| target_feature_def: DefId, | ||
| mut emit_err: impl FnMut(&'static str), | ||
| ) { | ||
| let Some(feature_def) = tcx.sess.target.features_for_correct_vector_abi() else { | ||
| return; | ||
| }; | ||
| let codegen_attrs = tcx.codegen_fn_attrs(target_feature_def); | ||
| for arg_abi in abi.args.iter().chain(std::iter::once(&abi.ret)) { | ||
| let size = arg_abi.layout.size; | ||
| if uses_vector_registers(&arg_abi.mode, &arg_abi.layout.backend_repr) { | ||
| // Find the first feature that provides at least this vector size. | ||
| let feature = match feature_def.iter().find(|(bits, _)| size.bits() <= *bits) { | ||
| Some((_, feature)) => feature, | ||
| None => { | ||
| emit_err("<no available feature for this size>"); | ||
| continue; | ||
| } | ||
| }; | ||
| let feature_sym = Symbol::intern(feature); | ||
| if !tcx.sess.unstable_target_features.contains(&feature_sym) | ||
| && !codegen_attrs.target_features.iter().any(|x| x.name == feature_sym) | ||
| { | ||
| emit_err(feature); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// Checks that the ABI of a given instance of a function does not contain vector-passed arguments | ||
| /// or return values for which the corresponding target feature is not enabled. | ||
| fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) { | ||
| let param_env = ParamEnv::reveal_all(); | ||
| let Ok(abi) = tcx.fn_abi_of_instance(param_env.and((instance, ty::List::empty()))) else { | ||
| // An error will be reported during codegen if we cannot determine the ABI of this | ||
| // function. | ||
| return; | ||
| }; | ||
| do_check_abi(tcx, abi, instance.def_id(), |required_feature| { | ||
| let span = tcx.def_span(instance.def_id()); | ||
| tcx.emit_node_span_lint( | ||
| ABI_UNSUPPORTED_VECTOR_TYPES, | ||
| CRATE_HIR_ID, | ||
| span, | ||
| AbiErrorDisabledVectorTypeDef { span, required_feature }, | ||
| ); | ||
| }) | ||
| } | ||
|
|
||
| fn call_site_abi_missing_features<'tcx>( | ||
| tcx: TyCtxt<'tcx>, | ||
| (callee, caller): (Ty<'tcx>, DefId), | ||
| ) -> Vec<String> { | ||
| let mut answer = vec![]; | ||
| let param_env = ParamEnv::reveal_all(); | ||
| let callee_abi = match *callee.kind() { | ||
| ty::FnPtr(..) => { | ||
| tcx.fn_abi_of_fn_ptr(param_env.and((callee.fn_sig(tcx), ty::List::empty()))) | ||
| } | ||
| ty::FnDef(def_id, args) => { | ||
| // Intrinsics are handled separately by the compiler. | ||
| if tcx.intrinsic(def_id).is_some() { | ||
| return vec![]; | ||
| } | ||
| let instance = ty::Instance::expect_resolve(tcx, param_env, def_id, args, DUMMY_SP); | ||
| tcx.fn_abi_of_instance(param_env.and((instance, ty::List::empty()))) | ||
| } | ||
| _ => { | ||
| panic!("Invalid function call"); | ||
| } | ||
| }; | ||
|
|
||
| let Ok(callee_abi) = callee_abi else { | ||
| // ABI failed to compute; this will not get through codegen. | ||
| return vec![]; | ||
| }; | ||
| do_check_abi(tcx, callee_abi, caller, |required_feature| { | ||
| answer.push(required_feature.to_string()); | ||
| }); | ||
| answer | ||
| } | ||
|
|
||
| /// Checks that a call expression does not try to pass a vector-passed argument which requires a | ||
| /// target feature that the caller does not have, as doing so causes UB because of ABI mismatch. | ||
| pub(super) fn check_call_site_abi<'tcx>( | ||
| tcx: TyCtxt<'tcx>, | ||
| callee: Ty<'tcx>, | ||
| span: Span, | ||
| caller: InstanceKind<'tcx>, | ||
| ) { | ||
| if callee.fn_sig(tcx).abi().is_rust() { | ||
| // "Rust" ABI never passes arguments in vector registers. | ||
| return; | ||
| } | ||
| for required_feature in tcx.call_site_abi_missing_features((callee, caller.def_id())) { | ||
| tcx.emit_node_span_lint( | ||
| ABI_UNSUPPORTED_VECTOR_TYPES, | ||
| CRATE_HIR_ID, | ||
| span, | ||
| AbiErrorDisabledVectorTypeCall { span, required_feature }, | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| pub(super) fn provide(providers: &mut Providers) { | ||
| *providers = Providers { check_instance_abi, call_site_abi_missing_features, ..*providers } | ||
| } | ||
|
|
||
| pub(super) fn should_check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) -> bool { | ||
| // We do not need to check the instance for feature-dependent ABI if we can determine that the | ||
| // function has "Rust" ABI, which is known not to be feature-dependent. | ||
| // Note that the check is still correct on Rust ABI functions, but somewhat expensive. Hence, | ||
| // checking for "Rust" ABI is just an optimization. | ||
| // We also avoid to try to determine the type of the instance, as doing so involves running a | ||
| // query that does not usually run for unchanged functions in incremental builds. | ||
| match instance.def { | ||
| InstanceKind::Item(def) | ||
| | InstanceKind::ReifyShim(def, ..) | ||
| | InstanceKind::FnPtrShim(def, ..) | ||
| | InstanceKind::Virtual(def, ..) | ||
| | InstanceKind::VTableShim(def) => { | ||
| // fn_sig ICEs on defs that are not functions. | ||
| if matches!(tcx.def_kind(def), DefKind::Fn | DefKind::AssocFn) { | ||
| !tcx.fn_sig(def).skip_binder().abi().is_rust() | ||
| } else if matches!(tcx.def_kind(def), DefKind::Ctor(..)) { | ||
| // Struct constructors are certainly always fine. | ||
| false | ||
| } else { | ||
| true | ||
| } | ||
| } | ||
| InstanceKind::DropGlue(..) | ||
| | InstanceKind::CloneShim(..) | ||
| | InstanceKind::FnPtrAddrShim(..) | ||
| | InstanceKind::AsyncDropGlueCtorShim(..) | ||
| | InstanceKind::ThreadLocalShim(..) => false, | ||
| InstanceKind::Intrinsic(..) | ||
| | InstanceKind::ClosureOnceShim { .. } | ||
| | InstanceKind::ConstructCoroutineInClosureShim { .. } => true, | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.