Revert "Emit error when calling/declaring functions with unavailable vectors."

This reverts commit 5af56cac38fa48e4228e5e123d060e85eb1acbf7.

6 files changed, 0 insertions, 227 deletions

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index f196d58c22d..a4c49a15905 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -16,7 +16,6 @@ declare_lint_pass! {
     /// that are used by other parts of the compiler.
     HardwiredLints => [
         // tidy-alphabetical-start
-        ABI_UNSUPPORTED_VECTOR_TYPES,
         ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
         AMBIGUOUS_ASSOCIATED_ITEMS,
         AMBIGUOUS_GLOB_IMPORTS,
@@ -5029,69 +5028,3 @@ declare_lint! {
     };
     crate_level_only
 }
-
-declare_lint! {
-    /// The `abi_unsupported_vector_types` lint detects function definitions and calls
-    /// whose ABI depends on enabling certain target features, but those features are not enabled.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,ignore (fails on non-x86_64)
-    /// extern "C" fn missing_target_feature(_: std::arch::x86_64::__m256) {
-    ///   todo!()
-    /// }
-    ///
-    /// #[target_feature(enable = "avx")]
-    /// unsafe extern "C" fn with_target_feature(_: std::arch::x86_64::__m256) {
-    ///   todo!()
-    /// }
-    ///
-    /// fn main() {
-    ///   let v = unsafe { std::mem::zeroed() };
-    ///   unsafe { with_target_feature(v); }
-    /// }
-    /// ```
-    ///
-    /// ```text
-    /// warning: ABI error: this function call uses a avx vector type, which is not enabled in the caller
-    ///  --> lint_example.rs:18:12
-    ///   |
-    ///   |   unsafe { with_target_feature(v); }
-    ///   |            ^^^^^^^^^^^^^^^^^^^^^^ function called here
-    ///   |
-    ///   = warning: 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 #116558 <https://github.com/rust-lang/rust/issues/116558>
-    ///   = help: consider enabling it globally (-C target-feature=+avx) or locally (#[target_feature(enable="avx")])
-    ///   = note: `#[warn(abi_unsupported_vector_types)]` on by default
-    ///
-    ///
-    /// warning: ABI error: this function definition uses a avx vector type, which is not enabled
-    ///  --> lint_example.rs:3:1
-    ///   |
-    ///   | pub extern "C" fn with_target_feature(_: std::arch::x86_64::__m256) {
-    ///   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
-    ///   |
-    ///   = warning: 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 #116558 <https://github.com/rust-lang/rust/issues/116558>
-    ///   = help: consider enabling it globally (-C target-feature=+avx) or locally (#[target_feature(enable="avx")])
-    /// ```
-    ///
-    ///
-    ///
-    /// ### Explanation
-    ///
-    /// The C ABI for `__m256` requires the value to be passed in an AVX register,
-    /// which is only possible when the `avx` target feature is enabled.
-    /// Therefore, `missing_target_feature` cannot be compiled without that target feature.
-    /// A similar (but complementary) message is triggered when `with_target_feature` is called
-    /// by a function that does not enable the `avx` target feature.
-    ///
-    /// Note that this lint is very similar to the `-Wpsabi` warning in `gcc`/`clang`.
-    pub ABI_UNSUPPORTED_VECTOR_TYPES,
-    Warn,
-    "this function call or definition uses a vector type which is not enabled",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #116558 <https://github.com/rust-lang/rust/issues/116558>",
-    };
-}
diff --git a/compiler/rustc_monomorphize/messages.ftl b/compiler/rustc_monomorphize/messages.ftl
index 6da387bbebc..7210701d482 100644
--- a/compiler/rustc_monomorphize/messages.ftl
+++ b/compiler/rustc_monomorphize/messages.ftl
@@ -1,12 +1,3 @@
-monomorphize_abi_error_disabled_vector_type_call =
-  ABI error: this function call uses a vector type that requires the `{$required_feature}` target feature, which is not enabled in the caller
-  .label = function called here
-  .help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
-monomorphize_abi_error_disabled_vector_type_def =
-  ABI error: this function definition uses a vector type that requires the `{$required_feature}` target feature, which is not enabled
-  .label = function defined here
-  .help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
-
 monomorphize_couldnt_dump_mono_stats =
     unexpected error occurred while dumping monomorphization stats: {$error}
 
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 3f9a0df0301..e5c59d60822 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -205,7 +205,6 @@
 //! this is not implemented however: a mono item will be produced
 //! regardless of whether it is actually needed or not.
 
-mod abi_check;
 mod move_check;
 
 use std::path::PathBuf;
@@ -767,7 +766,6 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                 self.used_mentioned_items.insert(MentionedItem::Fn(callee_ty));
                 let callee_ty = self.monomorphize(callee_ty);
                 self.check_fn_args_move_size(callee_ty, args, *fn_span, location);
-                abi_check::check_call_site_abi(tcx, callee_ty, *fn_span, self.body.source.instance);
                 visit_fn_use(self.tcx, callee_ty, true, source, &mut self.used_items)
             }
             mir::TerminatorKind::Drop { ref place, .. } => {
@@ -1209,9 +1207,6 @@ fn collect_items_of_instance<'tcx>(
     mentioned_items: &mut MonoItems<'tcx>,
     mode: CollectionMode,
 ) {
-    // Check the instance for feature-dependent ABI.
-    abi_check::check_instance_abi(tcx, instance);
-
     let body = tcx.instance_mir(instance.def);
     // Naively, in "used" collection mode, all functions get added to *both* `used_items` and
     // `mentioned_items`. Mentioned items processing will then notice that they have already been
diff --git a/compiler/rustc_monomorphize/src/collector/abi_check.rs b/compiler/rustc_monomorphize/src/collector/abi_check.rs
deleted file mode 100644
index 6b825019f20..00000000000
--- a/compiler/rustc_monomorphize/src/collector/abi_check.rs
+++ /dev/null
@@ -1,111 +0,0 @@
-//! 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_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::{Span, Symbol};
-use rustc_target::abi::call::{FnAbi, PassMode};
-use rustc_target::abi::{Abi, RegKind};
-
-use crate::errors::{AbiErrorDisabledVectorTypeCall, AbiErrorDisabledVectorTypeDef};
-
-fn uses_vector_registers(mode: &PassMode, abi: &Abi) -> 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!(abi, Abi::Vector { .. }),
-    }
-}
-
-fn do_check_abi<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    abi: &FnAbi<'tcx, Ty<'tcx>>,
-    target_feature_def: DefId,
-    emit_err: impl Fn(&'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.abi) {
-            // 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.
-pub(super) 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 },
-        );
-    })
-}
-
-/// 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>,
-    ty: Ty<'tcx>,
-    span: Span,
-    caller: InstanceKind<'tcx>,
-) {
-    let param_env = ParamEnv::reveal_all();
-    let callee_abi = match *ty.kind() {
-        ty::FnPtr(..) => tcx.fn_abi_of_fn_ptr(param_env.and((ty.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;
-            }
-            let instance = ty::Instance::expect_resolve(tcx, param_env, def_id, args, span);
-            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;
-    };
-    do_check_abi(tcx, callee_abi, caller.def_id(), |required_feature| {
-        tcx.emit_node_span_lint(
-            ABI_UNSUPPORTED_VECTOR_TYPES,
-            CRATE_HIR_ID,
-            span,
-            AbiErrorDisabledVectorTypeCall { span, required_feature },
-        );
-    })
-}
diff --git a/compiler/rustc_monomorphize/src/errors.rs b/compiler/rustc_monomorphize/src/errors.rs
index 5048a8d5d99..d5fae6e23cb 100644
--- a/compiler/rustc_monomorphize/src/errors.rs
+++ b/compiler/rustc_monomorphize/src/errors.rs
@@ -92,21 +92,3 @@ pub(crate) struct StartNotFound;
 pub(crate) struct UnknownCguCollectionMode<'a> {
     pub mode: &'a str,
 }
-
-#[derive(LintDiagnostic)]
-#[diag(monomorphize_abi_error_disabled_vector_type_def)]
-#[help]
-pub(crate) struct AbiErrorDisabledVectorTypeDef<'a> {
-    #[label]
-    pub span: Span,
-    pub required_feature: &'a str,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(monomorphize_abi_error_disabled_vector_type_call)]
-#[help]
-pub(crate) struct AbiErrorDisabledVectorTypeCall<'a> {
-    #[label]
-    pub span: Span,
-    pub required_feature: &'a str,
-}
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 0d16c9a96aa..e92366d5c5c 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -522,13 +522,6 @@ pub fn all_known_features() -> impl Iterator<Item = (&'static str, Stability)> {
         .map(|(f, s, _)| (f, s))
 }
 
-// These arrays represent the least-constraining feature that is required for vector types up to a
-// certain size to have their "proper" ABI on each architecture.
-// Note that they must be kept sorted by vector size.
-const X86_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
-    &[(128, "sse"), (256, "avx"), (512, "avx512f")];
-const AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "neon")];
-
 impl super::spec::Target {
     pub fn supported_target_features(
         &self,
@@ -550,16 +543,6 @@ impl super::spec::Target {
         }
     }
 
-    // Returns None if we do not support ABI checks on the given target yet.
-    pub fn features_for_correct_vector_abi(&self) -> Option<&'static [(u64, &'static str)]> {
-        match &*self.arch {
-            "x86" | "x86_64" => Some(X86_FEATURES_FOR_CORRECT_VECTOR_ABI),
-            "aarch64" => Some(AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI),
-            // FIXME: add support for non-tier1 architectures
-            _ => None,
-        }
-    }
-
     pub fn tied_target_features(&self) -> &'static [&'static [&'static str]] {
         match &*self.arch {
             "aarch64" | "arm64ec" => AARCH64_TIED_FEATURES,