From 5eb535c568de730a36bbf96f0ec1163942301b15 Mon Sep 17 00:00:00 2001
From: Skgland <3877590+Skgland@users.noreply.github.com>
Date: Sun, 6 Apr 2025 21:32:58 +0200
Subject: [PATCH] remove compiler support for `extern "rust-intrinsic"` blocks

---
 compiler/rustc_abi/src/extern_abi.rs          |   4 +-
 compiler/rustc_ast_lowering/src/stability.rs  |   4 -
 .../rustc_hir_analysis/src/check/check.rs     | 108 ++++++++----------
 .../rustc_hir_analysis/src/check/intrinsic.rs |   2 +-
 compiler/rustc_hir_analysis/src/check/mod.rs  |   9 --
 compiler/rustc_hir_analysis/src/collect.rs    |   8 +-
 compiler/rustc_hir_typeck/src/check.rs        |   4 +-
 compiler/rustc_hir_typeck/src/coercion.rs     |   5 -
 compiler/rustc_metadata/src/native_libs.rs    |   2 +-
 compiler/rustc_middle/src/ty/instance.rs      |   2 +-
 compiler/rustc_middle/src/ty/layout.rs        |   4 +-
 compiler/rustc_middle/src/ty/util.rs          |   7 +-
 compiler/rustc_passes/src/check_attr.rs       |   2 +-
 .../rustc_smir/src/rustc_internal/internal.rs |   1 -
 .../rustc_smir/src/rustc_smir/convert/ty.rs   |   1 -
 compiler/rustc_smir/src/stable_mir/ty.rs      |   1 -
 .../rustc_target/src/callconv/loongarch.rs    |  10 +-
 compiler/rustc_target/src/callconv/mod.rs     |  13 +--
 compiler/rustc_target/src/callconv/riscv.rs   |  10 +-
 compiler/rustc_target/src/callconv/x86.rs     |  11 +-
 compiler/rustc_target/src/spec/mod.rs         |  11 +-
 compiler/rustc_ty_utils/src/abi.rs            |   4 +-
 src/librustdoc/clean/types.rs                 |   3 -
 23 files changed, 79 insertions(+), 147 deletions(-)

diff --git a/compiler/rustc_abi/src/extern_abi.rs b/compiler/rustc_abi/src/extern_abi.rs
index 4d70afd4e0b..55f4845d216 100644
--- a/compiler/rustc_abi/src/extern_abi.rs
+++ b/compiler/rustc_abi/src/extern_abi.rs
@@ -60,7 +60,6 @@ pub enum ExternAbi {
     System {
         unwind: bool,
     },
-    RustIntrinsic,
     RustCall,
     /// *Not* a stable ABI, just directly use the Rust types to describe the ABI for LLVM. Even
     /// normally ABI-compatible Rust types can become ABI-incompatible with this ABI!
@@ -128,7 +127,6 @@ abi_impls! {
             RiscvInterruptS =><= "riscv-interrupt-s",
             RustCall =><= "rust-call",
             RustCold =><= "rust-cold",
-            RustIntrinsic =><= "rust-intrinsic",
             Stdcall { unwind: false } =><= "stdcall",
             Stdcall { unwind: true } =><= "stdcall-unwind",
             System { unwind: false } =><= "system",
@@ -199,7 +197,7 @@ impl ExternAbi {
     /// - are subject to change between compiler versions
     pub fn is_rustic_abi(self) -> bool {
         use ExternAbi::*;
-        matches!(self, Rust | RustCall | RustIntrinsic | RustCold)
+        matches!(self, Rust | RustCall | RustCold)
     }
 
     pub fn supports_varargs(self) -> bool {
diff --git a/compiler/rustc_ast_lowering/src/stability.rs b/compiler/rustc_ast_lowering/src/stability.rs
index a2004bbb39f..eb052ba1c6d 100644
--- a/compiler/rustc_ast_lowering/src/stability.rs
+++ b/compiler/rustc_ast_lowering/src/stability.rs
@@ -79,10 +79,6 @@ pub fn extern_abi_stability(abi: ExternAbi) -> Result<(), UnstableAbi> {
         | ExternAbi::SysV64 { .. }
         | ExternAbi::System { .. }
         | ExternAbi::EfiApi => Ok(()),
-        // implementation details
-        ExternAbi::RustIntrinsic => {
-            Err(UnstableAbi { abi, feature: sym::intrinsics, explain: GateReason::ImplDetail })
-        }
         ExternAbi::Unadjusted => {
             Err(UnstableAbi { abi, feature: sym::abi_unadjusted, explain: GateReason::ImplDetail })
         }
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index a0798656763..e3ed20e1b31 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -741,10 +741,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 
             for &assoc_item in assoc_items.in_definition_order() {
                 match assoc_item.kind {
-                    ty::AssocKind::Fn => {
-                        let abi = tcx.fn_sig(assoc_item.def_id).skip_binder().abi();
-                        forbid_intrinsic_abi(tcx, assoc_item.ident(tcx).span, abi);
-                    }
                     ty::AssocKind::Type if assoc_item.defaultness(tcx).has_value() => {
                         let trait_args = GenericArgs::identity_for_item(tcx, def_id);
                         let _: Result<_, rustc_errors::ErrorGuaranteed> = check_type_bounds(
@@ -788,65 +784,59 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             };
             check_abi(tcx, it.span, abi);
 
-            match abi {
-                ExternAbi::RustIntrinsic => {
-                    for item in items {
-                        intrinsic::check_intrinsic_type(
-                            tcx,
-                            item.id.owner_id.def_id,
-                            item.span,
-                            item.ident.name,
-                            abi,
-                        );
-                    }
+            for item in items {
+                let def_id = item.id.owner_id.def_id;
+
+                if tcx.has_attr(def_id, sym::rustc_intrinsic) {
+                    intrinsic::check_intrinsic_type(
+                        tcx,
+                        item.id.owner_id.def_id,
+                        item.span,
+                        item.ident.name,
+                        abi,
+                    );
                 }
 
-                _ => {
-                    for item in items {
-                        let def_id = item.id.owner_id.def_id;
-                        let generics = tcx.generics_of(def_id);
-                        let own_counts = generics.own_counts();
-                        if generics.own_params.len() - own_counts.lifetimes != 0 {
-                            let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts)
-                            {
-                                (_, 0) => ("type", "types", Some("u32")),
-                                // We don't specify an example value, because we can't generate
-                                // a valid value for any type.
-                                (0, _) => ("const", "consts", None),
-                                _ => ("type or const", "types or consts", None),
-                            };
-                            struct_span_code_err!(
-                                tcx.dcx(),
-                                item.span,
-                                E0044,
-                                "foreign items may not have {kinds} parameters",
-                            )
-                            .with_span_label(item.span, format!("can't have {kinds} parameters"))
-                            .with_help(
-                                // FIXME: once we start storing spans for type arguments, turn this
-                                // into a suggestion.
-                                format!(
-                                    "replace the {} parameters with concrete {}{}",
-                                    kinds,
-                                    kinds_pl,
-                                    egs.map(|egs| format!(" like `{egs}`")).unwrap_or_default(),
-                                ),
-                            )
-                            .emit();
-                        }
+                let generics = tcx.generics_of(def_id);
+                let own_counts = generics.own_counts();
+                if generics.own_params.len() - own_counts.lifetimes != 0 {
+                    let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) {
+                        (_, 0) => ("type", "types", Some("u32")),
+                        // We don't specify an example value, because we can't generate
+                        // a valid value for any type.
+                        (0, _) => ("const", "consts", None),
+                        _ => ("type or const", "types or consts", None),
+                    };
+                    struct_span_code_err!(
+                        tcx.dcx(),
+                        item.span,
+                        E0044,
+                        "foreign items may not have {kinds} parameters",
+                    )
+                    .with_span_label(item.span, format!("can't have {kinds} parameters"))
+                    .with_help(
+                        // FIXME: once we start storing spans for type arguments, turn this
+                        // into a suggestion.
+                        format!(
+                            "replace the {} parameters with concrete {}{}",
+                            kinds,
+                            kinds_pl,
+                            egs.map(|egs| format!(" like `{egs}`")).unwrap_or_default(),
+                        ),
+                    )
+                    .emit();
+                }
 
-                        let item = tcx.hir_foreign_item(item.id);
-                        match &item.kind {
-                            hir::ForeignItemKind::Fn(sig, _, _) => {
-                                require_c_abi_if_c_variadic(tcx, sig.decl, abi, item.span);
-                            }
-                            hir::ForeignItemKind::Static(..) => {
-                                check_static_inhabited(tcx, def_id);
-                                check_static_linkage(tcx, def_id);
-                            }
-                            _ => {}
-                        }
+                let item = tcx.hir_foreign_item(item.id);
+                match &item.kind {
+                    hir::ForeignItemKind::Fn(sig, _, _) => {
+                        require_c_abi_if_c_variadic(tcx, sig.decl, abi, item.span);
                     }
+                    hir::ForeignItemKind::Static(..) => {
+                        check_static_inhabited(tcx, def_id);
+                        check_static_linkage(tcx, def_id);
+                    }
+                    _ => {}
                 }
             }
         }
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 42d785c8dd0..0bf9e127989 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -1,4 +1,4 @@
-//! Type-checking for the rust-intrinsic intrinsics that the compiler exposes.
+//! Type-checking for the `#[rustc_intrinsic]` intrinsics that the compiler exposes.
 
 use rustc_abi::ExternAbi;
 use rustc_errors::codes::*;
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs
index 7c5d7b33a34..30921b6f055 100644
--- a/compiler/rustc_hir_analysis/src/check/mod.rs
+++ b/compiler/rustc_hir_analysis/src/check/mod.rs
@@ -137,15 +137,6 @@ fn get_owner_return_paths(
     })
 }
 
-/// Forbid defining intrinsics in Rust code,
-/// as they must always be defined by the compiler.
-// FIXME: Move this to a more appropriate place.
-pub fn forbid_intrinsic_abi(tcx: TyCtxt<'_>, sp: Span, abi: ExternAbi) {
-    if let ExternAbi::RustIntrinsic = abi {
-        tcx.dcx().span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
-    }
-}
-
 pub(super) fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) {
     // Only restricted on wasm target for now
     if !tcx.sess.target.is_like_wasm {
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 625f51dd29e..e9cd22435d9 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -42,7 +42,6 @@ use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, instrument};
 
-use crate::check::intrinsic::intrinsic_operation_unsafety;
 use crate::errors;
 use crate::hir_ty_lowering::errors::assoc_kind_str;
 use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer, RegionInferReason};
@@ -1704,18 +1703,13 @@ fn compute_sig_of_foreign_fn_decl<'tcx>(
     abi: ExternAbi,
     safety: hir::Safety,
 ) -> ty::PolyFnSig<'tcx> {
-    let safety = if abi == ExternAbi::RustIntrinsic {
-        intrinsic_operation_unsafety(tcx, def_id)
-    } else {
-        safety
-    };
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
     let fty =
         ItemCtxt::new(tcx, def_id).lowerer().lower_fn_ty(hir_id, safety, abi, decl, None, None);
 
     // Feature gate SIMD types in FFI, since I am not sure that the
     // ABIs are handled at all correctly. -huonw
-    if abi != ExternAbi::RustIntrinsic && !tcx.features().simd_ffi() {
+    if !tcx.features().simd_ffi() {
         let check = |hir_ty: &hir::Ty<'_>, ty: Ty<'_>| {
             if ty.is_simd() {
                 let snip = tcx
diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs
index dabae7b1d09..2189fdf0f34 100644
--- a/compiler/rustc_hir_typeck/src/check.rs
+++ b/compiler/rustc_hir_typeck/src/check.rs
@@ -5,7 +5,7 @@ use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
-use rustc_hir_analysis::check::{check_function_signature, forbid_intrinsic_abi};
+use rustc_hir_analysis::check::check_function_signature;
 use rustc_infer::infer::RegionVariableOrigin;
 use rustc_infer::traits::WellFormedLoc;
 use rustc_middle::ty::{self, Binder, Ty, TyCtxt};
@@ -50,8 +50,6 @@ pub(super) fn check_fn<'a, 'tcx>(
 
     let span = body.value.span;
 
-    forbid_intrinsic_abi(tcx, span, fn_sig.abi);
-
     GatherLocalsVisitor::new(fcx).visit_body(body);
 
     // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index f42ca3af2b3..f1571cf4c83 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -37,7 +37,6 @@
 
 use std::ops::Deref;
 
-use rustc_abi::ExternAbi;
 use rustc_attr_parsing::InlineAttr;
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, Diag, struct_span_code_err};
@@ -1240,10 +1239,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         };
         if let (Some(a_sig), Some(b_sig)) = (a_sig, b_sig) {
-            // Intrinsics are not coercible to function pointers.
-            if a_sig.abi() == ExternAbi::RustIntrinsic || b_sig.abi() == ExternAbi::RustIntrinsic {
-                return Err(TypeError::IntrinsicCast);
-            }
             // The signature must match.
             let (a_sig, b_sig) = self.normalize(new.span, (a_sig, b_sig));
             let sig = self
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 130a425e9c7..cfb0de8475c 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -207,7 +207,7 @@ impl<'tcx> Collector<'tcx> {
 
         let sess = self.tcx.sess;
 
-        if matches!(abi, ExternAbi::Rust | ExternAbi::RustIntrinsic) {
+        if matches!(abi, ExternAbi::Rust) {
             return;
         }
 
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index 55ebd15248c..07f2a602f2b 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -71,7 +71,7 @@ pub enum InstanceKind<'tcx> {
     /// - coroutines
     Item(DefId),
 
-    /// An intrinsic `fn` item (with `"rust-intrinsic"` ABI).
+    /// An intrinsic `fn` item (with`#[rustc_instrinsic]`).
     ///
     /// Alongside `Virtual`, this is the only `InstanceKind` that does not have its own callable MIR.
     /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index ebb6a8c08a5..7ebfebea44e 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1265,9 +1265,7 @@ pub fn fn_can_unwind(tcx: TyCtxt<'_>, fn_def_id: Option<DefId>, abi: ExternAbi)
         | CCmseNonSecureCall
         | CCmseNonSecureEntry
         | Unadjusted => false,
-        Rust | RustCall | RustCold | RustIntrinsic => {
-            tcx.sess.panic_strategy() == PanicStrategy::Unwind
-        }
+        Rust | RustCall | RustCold => tcx.sess.panic_strategy() == PanicStrategy::Unwind,
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index e4863896fc8..857b462b9eb 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -2,7 +2,7 @@
 
 use std::{fmt, iter};
 
-use rustc_abi::{ExternAbi, Float, Integer, IntegerType, Size};
+use rustc_abi::{Float, Integer, IntegerType, Size};
 use rustc_apfloat::Float as _;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -1719,10 +1719,7 @@ pub fn is_doc_notable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 /// the compiler to make some assumptions about its shape; if the user doesn't use a feature gate, they may
 /// cause an ICE that we otherwise may want to prevent.
 pub fn intrinsic_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::IntrinsicDef> {
-    if tcx.features().intrinsics()
-        && (matches!(tcx.fn_sig(def_id).skip_binder().abi(), ExternAbi::RustIntrinsic)
-            || tcx.has_attr(def_id, sym::rustc_intrinsic))
-    {
+    if tcx.features().intrinsics() && tcx.has_attr(def_id, sym::rustc_intrinsic) {
         let must_be_overridden = match tcx.hir_node_by_def_id(def_id) {
             hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn { has_body, .. }, .. }) => {
                 !has_body
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 669349f3380..9161b23428a 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1598,7 +1598,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         if target == Target::ForeignMod
             && let hir::Node::Item(item) = self.tcx.hir_node(hir_id)
             && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
-            && !matches!(abi, ExternAbi::Rust | ExternAbi::RustIntrinsic)
+            && !matches!(abi, ExternAbi::Rust)
         {
             return;
         }
diff --git a/compiler/rustc_smir/src/rustc_internal/internal.rs b/compiler/rustc_smir/src/rustc_internal/internal.rs
index 36b68cc1398..6e13b87c41d 100644
--- a/compiler/rustc_smir/src/rustc_internal/internal.rs
+++ b/compiler/rustc_smir/src/rustc_internal/internal.rs
@@ -491,7 +491,6 @@ impl RustcInternal for Abi {
             Abi::CCmseNonSecureCall => rustc_abi::ExternAbi::CCmseNonSecureCall,
             Abi::CCmseNonSecureEntry => rustc_abi::ExternAbi::CCmseNonSecureEntry,
             Abi::System { unwind } => rustc_abi::ExternAbi::System { unwind },
-            Abi::RustIntrinsic => rustc_abi::ExternAbi::RustIntrinsic,
             Abi::RustCall => rustc_abi::ExternAbi::RustCall,
             Abi::Unadjusted => rustc_abi::ExternAbi::Unadjusted,
             Abi::RustCold => rustc_abi::ExternAbi::RustCold,
diff --git a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
index 1ba25aa0e97..28fc68d5e49 100644
--- a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
+++ b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
@@ -871,7 +871,6 @@ impl<'tcx> Stable<'tcx> for rustc_abi::ExternAbi {
             ExternAbi::CCmseNonSecureCall => Abi::CCmseNonSecureCall,
             ExternAbi::CCmseNonSecureEntry => Abi::CCmseNonSecureEntry,
             ExternAbi::System { unwind } => Abi::System { unwind },
-            ExternAbi::RustIntrinsic => Abi::RustIntrinsic,
             ExternAbi::RustCall => Abi::RustCall,
             ExternAbi::Unadjusted => Abi::Unadjusted,
             ExternAbi::RustCold => Abi::RustCold,
diff --git a/compiler/rustc_smir/src/stable_mir/ty.rs b/compiler/rustc_smir/src/stable_mir/ty.rs
index 1efa2fe13c5..3fcbbb0e138 100644
--- a/compiler/rustc_smir/src/stable_mir/ty.rs
+++ b/compiler/rustc_smir/src/stable_mir/ty.rs
@@ -1093,7 +1093,6 @@ pub enum Abi {
     CCmseNonSecureCall,
     CCmseNonSecureEntry,
     System { unwind: bool },
-    RustIntrinsic,
     RustCall,
     Unadjusted,
     RustCold,
diff --git a/compiler/rustc_target/src/callconv/loongarch.rs b/compiler/rustc_target/src/callconv/loongarch.rs
index 209d7483e61..c779720f97b 100644
--- a/compiler/rustc_target/src/callconv/loongarch.rs
+++ b/compiler/rustc_target/src/callconv/loongarch.rs
@@ -1,6 +1,6 @@
 use rustc_abi::{
-    BackendRepr, ExternAbi, FieldsShape, HasDataLayout, Primitive, Reg, RegKind, Size,
-    TyAbiInterface, TyAndLayout, Variants,
+    BackendRepr, FieldsShape, HasDataLayout, Primitive, Reg, RegKind, Size, TyAbiInterface,
+    TyAndLayout, Variants,
 };
 
 use crate::callconv::{ArgAbi, ArgExtension, CastTarget, FnAbi, PassMode, Uniform};
@@ -364,15 +364,11 @@ where
     }
 }
 
-pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, abi: ExternAbi)
+pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
     C: HasDataLayout + HasTargetSpec,
 {
-    if abi == ExternAbi::RustIntrinsic {
-        return;
-    }
-
     let grlen = cx.data_layout().pointer_size.bits();
 
     for arg in fn_abi.args.iter_mut() {
diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs
index 55e39d093e2..7ecc46cc69d 100644
--- a/compiler/rustc_target/src/callconv/mod.rs
+++ b/compiler/rustc_target/src/callconv/mod.rs
@@ -717,16 +717,16 @@ impl<'a, Ty> FnAbi<'a, Ty> {
         }
     }
 
-    pub fn adjust_for_rust_abi<C>(&mut self, cx: &C, abi: ExternAbi)
+    pub fn adjust_for_rust_abi<C>(&mut self, cx: &C)
     where
         Ty: TyAbiInterface<'a, C> + Copy,
         C: HasDataLayout + HasTargetSpec,
     {
         let spec = cx.target_spec();
         match &*spec.arch {
-            "x86" => x86::compute_rust_abi_info(cx, self, abi),
-            "riscv32" | "riscv64" => riscv::compute_rust_abi_info(cx, self, abi),
-            "loongarch64" => loongarch::compute_rust_abi_info(cx, self, abi),
+            "x86" => x86::compute_rust_abi_info(cx, self),
+            "riscv32" | "riscv64" => riscv::compute_rust_abi_info(cx, self),
+            "loongarch64" => loongarch::compute_rust_abi_info(cx, self),
             "aarch64" => aarch64::compute_rust_abi_info(cx, self),
             _ => {}
         };
@@ -850,10 +850,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
                     //
                     // Note that the intrinsic ABI is exempt here as those are not
                     // real functions anyway, and the backend expects very specific types.
-                    if abi != ExternAbi::RustIntrinsic
-                        && spec.simd_types_indirect
-                        && !can_pass_simd_directly(arg)
-                    {
+                    if spec.simd_types_indirect && !can_pass_simd_directly(arg) {
                         arg.make_indirect();
                     }
                 }
diff --git a/compiler/rustc_target/src/callconv/riscv.rs b/compiler/rustc_target/src/callconv/riscv.rs
index 7368e225efa..cd1d3cd1eee 100644
--- a/compiler/rustc_target/src/callconv/riscv.rs
+++ b/compiler/rustc_target/src/callconv/riscv.rs
@@ -5,8 +5,8 @@
 // https://github.com/llvm/llvm-project/blob/8e780252a7284be45cf1ba224cabd884847e8e92/clang/lib/CodeGen/TargetInfo.cpp#L9311-L9773
 
 use rustc_abi::{
-    BackendRepr, ExternAbi, FieldsShape, HasDataLayout, Primitive, Reg, RegKind, Size,
-    TyAbiInterface, TyAndLayout, Variants,
+    BackendRepr, FieldsShape, HasDataLayout, Primitive, Reg, RegKind, Size, TyAbiInterface,
+    TyAndLayout, Variants,
 };
 
 use crate::callconv::{ArgAbi, ArgExtension, CastTarget, FnAbi, PassMode, Uniform};
@@ -370,15 +370,11 @@ where
     }
 }
 
-pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, abi: ExternAbi)
+pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
     C: HasDataLayout + HasTargetSpec,
 {
-    if abi == ExternAbi::RustIntrinsic {
-        return;
-    }
-
     let xlen = cx.data_layout().pointer_size.bits();
 
     for arg in fn_abi.args.iter_mut() {
diff --git a/compiler/rustc_target/src/callconv/x86.rs b/compiler/rustc_target/src/callconv/x86.rs
index ba3c1406211..8328f818f9b 100644
--- a/compiler/rustc_target/src/callconv/x86.rs
+++ b/compiler/rustc_target/src/callconv/x86.rs
@@ -1,6 +1,6 @@
 use rustc_abi::{
-    AddressSpace, Align, BackendRepr, ExternAbi, HasDataLayout, Primitive, Reg, RegKind,
-    TyAbiInterface, TyAndLayout,
+    AddressSpace, Align, BackendRepr, HasDataLayout, Primitive, Reg, RegKind, TyAbiInterface,
+    TyAndLayout,
 };
 
 use crate::callconv::{ArgAttribute, FnAbi, PassMode};
@@ -193,7 +193,7 @@ pub(crate) fn fill_inregs<'a, Ty, C>(
     }
 }
 
-pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, abi: ExternAbi)
+pub(crate) fn compute_rust_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
     C: HasDataLayout + HasTargetSpec,
@@ -201,10 +201,7 @@ where
     // Avoid returning floats in x87 registers on x86 as loading and storing from x87
     // registers will quiet signalling NaNs. Also avoid using SSE registers since they
     // are not always available (depending on target features).
-    if !fn_abi.ret.is_ignore()
-        // Intrinsics themselves are not "real" functions, so theres no need to change their ABIs.
-        && abi != ExternAbi::RustIntrinsic
-    {
+    if !fn_abi.ret.is_ignore() {
         let has_float = match fn_abi.ret.layout.backend_repr {
             BackendRepr::Scalar(s) => matches!(s.primitive(), Primitive::Float(_)),
             BackendRepr::ScalarPair(s1, s2) => {
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 79f73ef28b3..64171fcc7ab 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -2962,14 +2962,9 @@ impl Target {
     pub fn is_abi_supported(&self, abi: ExternAbi) -> bool {
         use ExternAbi::*;
         match abi {
-            Rust
-            | C { .. }
-            | System { .. }
-            | RustIntrinsic
-            | RustCall
-            | Unadjusted
-            | Cdecl { .. }
-            | RustCold => true,
+            Rust | C { .. } | System { .. } | RustCall | Unadjusted | Cdecl { .. } | RustCold => {
+                true
+            }
             EfiApi => {
                 ["arm", "aarch64", "riscv32", "riscv64", "x86", "x86_64"].contains(&&self.arch[..])
             }
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 48d5a4a0fcb..3d4ab33240a 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -244,7 +244,7 @@ fn fn_sig_for_fn_abi<'tcx>(
 fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: ExternAbi, c_variadic: bool) -> Conv {
     use rustc_abi::ExternAbi::*;
     match tcx.sess.target.adjust_abi(abi, c_variadic) {
-        RustIntrinsic | Rust | RustCall => Conv::Rust,
+        Rust | RustCall => Conv::Rust,
 
         // This is intentionally not using `Conv::Cold`, as that has to preserve
         // even SIMD registers, which is generally not a good trade-off.
@@ -660,7 +660,7 @@ fn fn_abi_adjust_for_abi<'tcx>(
     let tcx = cx.tcx();
 
     if abi.is_rustic_abi() {
-        fn_abi.adjust_for_rust_abi(cx, abi);
+        fn_abi.adjust_for_rust_abi(cx);
 
         // Look up the deduced parameter attributes for this function, if we have its def ID and
         // we're optimizing in non-incremental mode. We'll tag its parameters with those attributes
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index d3ddb77c0b3..06e75fe1764 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -11,7 +11,6 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE, LocalDefId};
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{BodyId, Mutability};
-use rustc_hir_analysis::check::intrinsic::intrinsic_operation_unsafety;
 use rustc_index::IndexVec;
 use rustc_metadata::rendered_const;
 use rustc_middle::span_bug;
@@ -687,8 +686,6 @@ impl Item {
                 hir::FnHeader {
                     safety: if tcx.codegen_fn_attrs(def_id).safe_target_features {
                         hir::HeaderSafety::SafeTargetFeatures
-                    } else if abi == ExternAbi::RustIntrinsic {
-                        intrinsic_operation_unsafety(tcx, def_id.expect_local()).into()
                     } else {
                         safety.into()
                     },