remove platform-intrinsics ABI; make SIMD intrinsics be regular intrinsics

25 files changed, 179 insertions, 170 deletions

diff --git a/compiler/rustc_codegen_cranelift/example/float-minmax-pass.rs b/compiler/rustc_codegen_cranelift/example/float-minmax-pass.rs
index 80a2776ca1e..eebd77083ec 100644
--- a/compiler/rustc_codegen_cranelift/example/float-minmax-pass.rs
+++ b/compiler/rustc_codegen_cranelift/example/float-minmax-pass.rs
@@ -4,14 +4,14 @@
 
 // Test that the simd_f{min,max} intrinsics produce the correct results.
 
-#![feature(repr_simd, platform_intrinsics)]
+#![feature(repr_simd, intrinsics)]
 #![allow(non_camel_case_types)]
 
 #[repr(simd)]
 #[derive(Copy, Clone, PartialEq, Debug)]
 struct f32x4(pub f32, pub f32, pub f32, pub f32);
 
-extern "platform-intrinsic" {
+extern "intrinsic" {
     fn simd_fmin<T>(x: T, y: T) -> T;
     fn simd_fmax<T>(x: T, y: T) -> T;
 }
diff --git a/compiler/rustc_error_codes/src/error_codes/E0511.md b/compiler/rustc_error_codes/src/error_codes/E0511.md
index 5351a685eb5..681f4e611c3 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0511.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0511.md
@@ -3,9 +3,9 @@ Invalid monomorphization of an intrinsic function was used.
 Erroneous code example:
 
 ```compile_fail,E0511
-#![feature(platform_intrinsics)]
+#![feature(intrinsics)]
 
-extern "platform-intrinsic" {
+extern "rust-intrinsic" {
     fn simd_add<T>(a: T, b: T) -> T;
 }
 
@@ -19,13 +19,13 @@ The generic type has to be a SIMD type. Example:
 
 ```
 #![feature(repr_simd)]
-#![feature(platform_intrinsics)]
+#![feature(intrinsics)]
 
 #[repr(simd)]
 #[derive(Copy, Clone)]
 struct i32x2(i32, i32);
 
-extern "platform-intrinsic" {
+extern "rust-intrinsic" {
     fn simd_add<T>(a: T, b: T) -> T;
 }
 
diff --git a/compiler/rustc_feature/src/removed.rs b/compiler/rustc_feature/src/removed.rs
index 008c59e1be3..05bb7480732 100644
--- a/compiler/rustc_feature/src/removed.rs
+++ b/compiler/rustc_feature/src/removed.rs
@@ -156,6 +156,9 @@ declare_features! (
      Some("removed in favor of `#![feature(marker_trait_attr)]`")),
     (removed, panic_implementation, "1.28.0", Some(44489),
      Some("subsumed by `#[panic_handler]`")),
+    /// Allows `extern "platform-intrinsic" { ... }`.
+    (removed, platform_intrinsics, "1.4.0", Some(27731),
+     Some("SIMD intrinsics use the regular intrinsics ABI now")),
     /// Allows using `#![plugin(myplugin)]`.
     (removed, plugin, "1.75.0", Some(29597),
      Some("plugins are no longer supported")),
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 93c183a65ef..eb107e6ef3f 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -259,8 +259,6 @@ declare_features! (
     (internal, needs_panic_runtime, "1.10.0", Some(32837)),
     /// Allows using the `#![panic_runtime]` attribute.
     (internal, panic_runtime, "1.10.0", Some(32837)),
-    /// Allows `extern "platform-intrinsic" { ... }`.
-    (internal, platform_intrinsics, "1.4.0", Some(27731)),
     /// Allows using `#[rustc_allow_const_fn_unstable]`.
     /// This is an attribute on `const fn` for the same
     /// purpose as `#[allow_internal_unstable]`.
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index deabb9c3738..3d9aa428c74 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -612,17 +612,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     }
                 }
 
-                Abi::PlatformIntrinsic => {
-                    for item in items {
-                        intrinsic::check_platform_intrinsic_type(
-                            tcx,
-                            item.id.owner_id.def_id,
-                            item.span,
-                            item.ident.name,
-                        );
-                    }
-                }
-
                 _ => {
                     for item in items {
                         let def_id = item.id.owner_id.def_id;
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index d7277b22c84..f4b601f58b9 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -510,6 +510,77 @@ pub fn check_intrinsic_type(
 
             sym::debug_assertions => (0, 1, Vec::new(), tcx.types.bool),
 
+            sym::simd_eq
+            | sym::simd_ne
+            | sym::simd_lt
+            | sym::simd_le
+            | sym::simd_gt
+            | sym::simd_ge => (2, 0, vec![param(0), param(0)], param(1)),
+            sym::simd_add
+            | sym::simd_sub
+            | sym::simd_mul
+            | sym::simd_rem
+            | sym::simd_div
+            | sym::simd_shl
+            | sym::simd_shr
+            | sym::simd_and
+            | sym::simd_or
+            | sym::simd_xor
+            | sym::simd_fmin
+            | sym::simd_fmax
+            | sym::simd_fpow
+            | sym::simd_saturating_add
+            | sym::simd_saturating_sub => (1, 0, vec![param(0), param(0)], param(0)),
+            sym::simd_arith_offset => (2, 0, vec![param(0), param(1)], param(0)),
+            sym::simd_neg
+            | sym::simd_bswap
+            | sym::simd_bitreverse
+            | sym::simd_ctlz
+            | sym::simd_cttz
+            | sym::simd_fsqrt
+            | sym::simd_fsin
+            | sym::simd_fcos
+            | sym::simd_fexp
+            | sym::simd_fexp2
+            | sym::simd_flog2
+            | sym::simd_flog10
+            | sym::simd_flog
+            | sym::simd_fabs
+            | sym::simd_ceil
+            | sym::simd_floor
+            | sym::simd_round
+            | sym::simd_trunc => (1, 0, vec![param(0)], param(0)),
+            sym::simd_fpowi => (1, 0, vec![param(0), tcx.types.i32], param(0)),
+            sym::simd_fma => (1, 0, vec![param(0), param(0), param(0)], param(0)),
+            sym::simd_gather => (3, 0, vec![param(0), param(1), param(2)], param(0)),
+            sym::simd_masked_load => (3, 0, vec![param(0), param(1), param(2)], param(2)),
+            sym::simd_masked_store => (3, 0, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
+            sym::simd_scatter => (3, 0, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
+            sym::simd_insert => (2, 0, vec![param(0), tcx.types.u32, param(1)], param(0)),
+            sym::simd_extract => (2, 0, vec![param(0), tcx.types.u32], param(1)),
+            sym::simd_cast
+            | sym::simd_as
+            | sym::simd_cast_ptr
+            | sym::simd_expose_addr
+            | sym::simd_from_exposed_addr => (2, 0, vec![param(0)], param(1)),
+            sym::simd_bitmask => (2, 0, vec![param(0)], param(1)),
+            sym::simd_select | sym::simd_select_bitmask => {
+                (2, 0, vec![param(0), param(1), param(1)], param(1))
+            }
+            sym::simd_reduce_all | sym::simd_reduce_any => (1, 0, vec![param(0)], tcx.types.bool),
+            sym::simd_reduce_add_ordered | sym::simd_reduce_mul_ordered => {
+                (2, 0, vec![param(0), param(1)], param(1))
+            }
+            sym::simd_reduce_add_unordered
+            | sym::simd_reduce_mul_unordered
+            | sym::simd_reduce_and
+            | sym::simd_reduce_or
+            | sym::simd_reduce_xor
+            | sym::simd_reduce_min
+            | sym::simd_reduce_max => (2, 0, vec![param(0)], param(1)),
+            sym::simd_shuffle => (3, 0, vec![param(0), param(0), param(1)], param(2)),
+            sym::simd_shuffle_generic => (2, 1, vec![param(0), param(0)], param(1)),
+
             other => {
                 tcx.dcx().emit_err(UnrecognizedIntrinsicFunction { span, name: other });
                 return;
@@ -521,102 +592,3 @@ pub fn check_intrinsic_type(
     let sig = ty::Binder::bind_with_vars(sig, bound_vars);
     equate_intrinsic_type(tcx, span, intrinsic_id, n_tps, n_lts, n_cts, sig)
 }
-
-/// Type-check `extern "platform-intrinsic" { ... }` functions.
-pub fn check_platform_intrinsic_type(
-    tcx: TyCtxt<'_>,
-    intrinsic_id: LocalDefId,
-    span: Span,
-    name: Symbol,
-) {
-    let generics = tcx.generics_of(intrinsic_id);
-    let param = |n| {
-        if let Some(&ty::GenericParamDef {
-            name, kind: ty::GenericParamDefKind::Type { .. }, ..
-        }) = generics.opt_param_at(n as usize, tcx)
-        {
-            Ty::new_param(tcx, n, name)
-        } else {
-            Ty::new_error_with_message(tcx, span, "expected param")
-        }
-    };
-
-    let (n_tps, n_cts, inputs, output) = match name {
-        sym::simd_eq | sym::simd_ne | sym::simd_lt | sym::simd_le | sym::simd_gt | sym::simd_ge => {
-            (2, 0, vec![param(0), param(0)], param(1))
-        }
-        sym::simd_add
-        | sym::simd_sub
-        | sym::simd_mul
-        | sym::simd_rem
-        | sym::simd_div
-        | sym::simd_shl
-        | sym::simd_shr
-        | sym::simd_and
-        | sym::simd_or
-        | sym::simd_xor
-        | sym::simd_fmin
-        | sym::simd_fmax
-        | sym::simd_fpow
-        | sym::simd_saturating_add
-        | sym::simd_saturating_sub => (1, 0, vec![param(0), param(0)], param(0)),
-        sym::simd_arith_offset => (2, 0, vec![param(0), param(1)], param(0)),
-        sym::simd_neg
-        | sym::simd_bswap
-        | sym::simd_bitreverse
-        | sym::simd_ctlz
-        | sym::simd_cttz
-        | sym::simd_fsqrt
-        | sym::simd_fsin
-        | sym::simd_fcos
-        | sym::simd_fexp
-        | sym::simd_fexp2
-        | sym::simd_flog2
-        | sym::simd_flog10
-        | sym::simd_flog
-        | sym::simd_fabs
-        | sym::simd_ceil
-        | sym::simd_floor
-        | sym::simd_round
-        | sym::simd_trunc => (1, 0, vec![param(0)], param(0)),
-        sym::simd_fpowi => (1, 0, vec![param(0), tcx.types.i32], param(0)),
-        sym::simd_fma => (1, 0, vec![param(0), param(0), param(0)], param(0)),
-        sym::simd_gather => (3, 0, vec![param(0), param(1), param(2)], param(0)),
-        sym::simd_masked_load => (3, 0, vec![param(0), param(1), param(2)], param(2)),
-        sym::simd_masked_store => (3, 0, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
-        sym::simd_scatter => (3, 0, vec![param(0), param(1), param(2)], Ty::new_unit(tcx)),
-        sym::simd_insert => (2, 0, vec![param(0), tcx.types.u32, param(1)], param(0)),
-        sym::simd_extract => (2, 0, vec![param(0), tcx.types.u32], param(1)),
-        sym::simd_cast
-        | sym::simd_as
-        | sym::simd_cast_ptr
-        | sym::simd_expose_addr
-        | sym::simd_from_exposed_addr => (2, 0, vec![param(0)], param(1)),
-        sym::simd_bitmask => (2, 0, vec![param(0)], param(1)),
-        sym::simd_select | sym::simd_select_bitmask => {
-            (2, 0, vec![param(0), param(1), param(1)], param(1))
-        }
-        sym::simd_reduce_all | sym::simd_reduce_any => (1, 0, vec![param(0)], tcx.types.bool),
-        sym::simd_reduce_add_ordered | sym::simd_reduce_mul_ordered => {
-            (2, 0, vec![param(0), param(1)], param(1))
-        }
-        sym::simd_reduce_add_unordered
-        | sym::simd_reduce_mul_unordered
-        | sym::simd_reduce_and
-        | sym::simd_reduce_or
-        | sym::simd_reduce_xor
-        | sym::simd_reduce_min
-        | sym::simd_reduce_max => (2, 0, vec![param(0)], param(1)),
-        sym::simd_shuffle => (3, 0, vec![param(0), param(0), param(1)], param(2)),
-        sym::simd_shuffle_generic => (2, 1, vec![param(0), param(0)], param(1)),
-        _ => {
-            let msg = format!("unrecognized platform-specific intrinsic function: `{name}`");
-            tcx.dcx().span_err(span, msg);
-            return;
-        }
-    };
-
-    let sig = tcx.mk_fn_sig(inputs, output, false, hir::Unsafety::Unsafe, Abi::PlatformIntrinsic);
-    let sig = ty::Binder::dummy(sig);
-    equate_intrinsic_type(tcx, span, intrinsic_id, n_tps, 0, n_cts, sig)
-}
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs
index 36a92a4cf7c..24280dbf0b3 100644
--- a/compiler/rustc_hir_analysis/src/check/mod.rs
+++ b/compiler/rustc_hir_analysis/src/check/mod.rs
@@ -142,7 +142,7 @@ fn get_owner_return_paths(
 /// 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: Abi) {
-    if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
+    if let Abi::RustIntrinsic = abi {
         tcx.dcx().span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index e9c9ec6ba53..126766ce278 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -1677,10 +1677,7 @@ fn compute_sig_of_foreign_fn_decl<'tcx>(
 
     // Feature gate SIMD types in FFI, since I am not sure that the
     // ABIs are handled at all correctly. -huonw
-    if abi != abi::Abi::RustIntrinsic
-        && abi != abi::Abi::PlatformIntrinsic
-        && !tcx.features().simd_ffi
-    {
+    if abi != abi::Abi::RustIntrinsic && !tcx.features().simd_ffi {
         let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
             if ty.is_simd() {
                 let snip = tcx
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 9f6175eac13..1d1f58c6332 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1173,11 +1173,7 @@ 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() == Abi::RustIntrinsic
-                || a_sig.abi() == Abi::PlatformIntrinsic
-                || b_sig.abi() == Abi::RustIntrinsic
-                || b_sig.abi() == Abi::PlatformIntrinsic
-            {
+            if a_sig.abi() == Abi::RustIntrinsic || b_sig.abi() == Abi::RustIntrinsic {
                 return Err(TypeError::IntrinsicCast);
             }
             // The signature must match.
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index e4ebae2a973..2ea891ce04d 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -1587,10 +1587,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
     }
 
     fn is_internal_abi(&self, abi: SpecAbi) -> bool {
-        matches!(
-            abi,
-            SpecAbi::Rust | SpecAbi::RustCall | SpecAbi::RustIntrinsic | SpecAbi::PlatformIntrinsic
-        )
+        matches!(abi, SpecAbi::Rust | SpecAbi::RustCall | SpecAbi::RustIntrinsic)
     }
 
     /// Find any fn-ptr types with external ABIs in `ty`.
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 5e20a03bbc0..cdcc586b09e 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -99,7 +99,7 @@ impl<'tcx> Collector<'tcx> {
 
         let sess = self.tcx.sess;
 
-        if matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic) {
+        if matches!(abi, Abi::Rust | Abi::RustIntrinsic) {
             return;
         }
 
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index c1e33fe114f..38aca3326d3 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1244,7 +1244,6 @@ pub fn fn_can_unwind(tcx: TyCtxt<'_>, fn_def_id: Option<DefId>, abi: SpecAbi) ->
         | RiscvInterruptS
         | CCmseNonSecureCall
         | Wasm
-        | PlatformIntrinsic
         | Unadjusted => false,
         Rust | RustCall | RustCold | RustIntrinsic => {
             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 72a1905c147..5ead620927c 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1643,7 +1643,7 @@ pub fn is_doc_notable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 
 /// Determines whether an item is an intrinsic by Abi. or by whether it has a `rustc_intrinsic` attribute
 pub fn intrinsic(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<Symbol> {
-    if matches!(tcx.fn_sig(def_id).skip_binder().abi(), Abi::RustIntrinsic | Abi::PlatformIntrinsic)
+    if matches!(tcx.fn_sig(def_id).skip_binder().abi(), Abi::RustIntrinsic)
         || tcx.has_attr(def_id, sym::rustc_intrinsic)
     {
         Some(tcx.item_name(def_id.into()))
diff --git a/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs b/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs
index 663abbece85..0dc06524c79 100644
--- a/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs
+++ b/compiler/rustc_mir_transform/src/ffi_unwind_calls.rs
@@ -34,7 +34,6 @@ fn abi_can_unwind(abi: Abi) -> bool {
         | CCmseNonSecureCall
         | Wasm
         | RustIntrinsic
-        | PlatformIntrinsic
         | Unadjusted => false,
         Rust | RustCall | RustCold => true,
     }
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index d8ae82d11bc..194533047d4 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1389,7 +1389,7 @@ 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, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
+            && !matches!(abi, Abi::Rust | Abi::RustIntrinsic)
         {
             return;
         }
@@ -2071,7 +2071,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     ) -> bool {
         if let Target::ForeignFn = target
             && let hir::Node::Item(Item {
-                kind: ItemKind::ForeignMod { abi: Abi::RustIntrinsic | Abi::PlatformIntrinsic, .. },
+                kind: ItemKind::ForeignMod { abi: Abi::RustIntrinsic, .. },
                 ..
             }) = self.tcx.parent_hir_node(hir_id)
         {
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index 19272b52b32..05c833cdfb6 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -173,10 +173,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
         // If the current node is a function, has const stability attributes and if it doesn not have an intrinsic ABI,
         // check if the function/method is const or the parent impl block is const
         if let (Some(const_span), Some(fn_sig)) = (const_span, fn_sig) {
-            if fn_sig.header.abi != Abi::RustIntrinsic
-                && fn_sig.header.abi != Abi::PlatformIntrinsic
-                && !fn_sig.header.is_const()
-            {
+            if fn_sig.header.abi != Abi::RustIntrinsic && !fn_sig.header.is_const() {
                 if !self.in_trait_impl
                     || (self.in_trait_impl && !self.tcx.is_const_fn_raw(def_id.to_def_id()))
                 {
diff --git a/compiler/rustc_smir/src/rustc_internal/internal.rs b/compiler/rustc_smir/src/rustc_internal/internal.rs
index 6bbfcff5e87..2cc9bc31873 100644
--- a/compiler/rustc_smir/src/rustc_internal/internal.rs
+++ b/compiler/rustc_smir/src/rustc_internal/internal.rs
@@ -457,7 +457,6 @@ impl RustcInternal for Abi {
             Abi::System { unwind } => rustc_target::spec::abi::Abi::System { unwind },
             Abi::RustIntrinsic => rustc_target::spec::abi::Abi::RustIntrinsic,
             Abi::RustCall => rustc_target::spec::abi::Abi::RustCall,
-            Abi::PlatformIntrinsic => rustc_target::spec::abi::Abi::PlatformIntrinsic,
             Abi::Unadjusted => rustc_target::spec::abi::Abi::Unadjusted,
             Abi::RustCold => rustc_target::spec::abi::Abi::RustCold,
             Abi::RiscvInterruptM => rustc_target::spec::abi::Abi::RiscvInterruptM,
diff --git a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
index 29081418200..a066b9ed3aa 100644
--- a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
+++ b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
@@ -833,7 +833,6 @@ impl<'tcx> Stable<'tcx> for rustc_target::spec::abi::Abi {
             abi::Abi::System { unwind } => Abi::System { unwind },
             abi::Abi::RustIntrinsic => Abi::RustIntrinsic,
             abi::Abi::RustCall => Abi::RustCall,
-            abi::Abi::PlatformIntrinsic => Abi::PlatformIntrinsic,
             abi::Abi::Unadjusted => Abi::Unadjusted,
             abi::Abi::RustCold => Abi::RustCold,
             abi::Abi::RiscvInterruptM => Abi::RiscvInterruptM,
diff --git a/compiler/rustc_target/src/spec/abi/mod.rs b/compiler/rustc_target/src/spec/abi/mod.rs
index 6231787bb9f..388e76d83e2 100644
--- a/compiler/rustc_target/src/spec/abi/mod.rs
+++ b/compiler/rustc_target/src/spec/abi/mod.rs
@@ -54,7 +54,6 @@ pub enum Abi {
     },
     RustIntrinsic,
     RustCall,
-    PlatformIntrinsic,
     Unadjusted,
     /// For things unlikely to be called, where reducing register pressure in
     /// `extern "Rust"` callers is worth paying extra cost in the callee.
@@ -129,7 +128,6 @@ const AbiDatas: &[AbiData] = &[
     AbiData { abi: Abi::System { unwind: true }, name: "system-unwind" },
     AbiData { abi: Abi::RustIntrinsic, name: "rust-intrinsic" },
     AbiData { abi: Abi::RustCall, name: "rust-call" },
-    AbiData { abi: Abi::PlatformIntrinsic, name: "platform-intrinsic" },
     AbiData { abi: Abi::Unadjusted, name: "unadjusted" },
     AbiData { abi: Abi::RustCold, name: "rust-cold" },
     AbiData { abi: Abi::RiscvInterruptM, name: "riscv-interrupt-m" },
@@ -199,10 +197,6 @@ pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
             feature: sym::intrinsics,
             explain: "intrinsics are subject to change",
         }),
-        "platform-intrinsic" => Err(AbiDisabled::Unstable {
-            feature: sym::platform_intrinsics,
-            explain: "platform intrinsics are experimental and possibly buggy",
-        }),
         "vectorcall" => Err(AbiDisabled::Unstable {
             feature: sym::abi_vectorcall,
             explain: "vectorcall is experimental and subject to change",
@@ -299,11 +293,10 @@ impl Abi {
             System { unwind: true } => 28,
             RustIntrinsic => 29,
             RustCall => 30,
-            PlatformIntrinsic => 31,
-            Unadjusted => 32,
-            RustCold => 33,
-            RiscvInterruptM => 34,
-            RiscvInterruptS => 35,
+            Unadjusted => 31,
+            RustCold => 32,
+            RiscvInterruptM => 33,
+            RiscvInterruptS => 34,
         };
         debug_assert!(
             AbiDatas
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index d04bcb2d78a..084a8b9db81 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -2448,7 +2448,6 @@ impl Target {
             | System { .. }
             | RustIntrinsic
             | RustCall
-            | PlatformIntrinsic
             | Unadjusted
             | Cdecl { .. }
             | RustCold => true,
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 638c9a53d22..43042dbd366 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -312,7 +312,7 @@ fn fn_sig_for_fn_abi<'tcx>(
 fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi, c_variadic: bool) -> Conv {
     use rustc_target::spec::abi::Abi::*;
     match tcx.sess.target.adjust_abi(abi, c_variadic) {
-        RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust,
+        RustIntrinsic | 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.
@@ -605,7 +605,7 @@ fn fn_abi_new_uncached<'tcx>(
     let linux_powerpc_gnu_like =
         target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
     use SpecAbi::*;
-    let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
+    let rust_abi = matches!(sig.abi, RustIntrinsic | Rust | RustCall);
 
     let is_drop_in_place =
         fn_def_id.is_some() && fn_def_id == cx.tcx.lang_items().drop_in_place_fn();
@@ -713,11 +713,7 @@ fn fn_abi_adjust_for_abi<'tcx>(
         return Ok(());
     }
 
-    if abi == SpecAbi::Rust
-        || abi == SpecAbi::RustCall
-        || abi == SpecAbi::RustIntrinsic
-        || abi == SpecAbi::PlatformIntrinsic
-    {
+    if abi == SpecAbi::Rust || abi == SpecAbi::RustCall || abi == SpecAbi::RustIntrinsic {
         // 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
         // as appropriate.
@@ -753,12 +749,11 @@ fn fn_abi_adjust_for_abi<'tcx>(
                 // target feature sets. Some more information about this
                 // issue can be found in #44367.
                 //
-                // Note that the platform intrinsic ABI is exempt here as
+                // Note that the intrinsic ABI is exempt here as
                 // that's how we connect up to LLVM and it's unstable
                 // anyway, we control all calls to it in libstd.
                 Abi::Vector { .. }
-                    if abi != SpecAbi::PlatformIntrinsic
-                        && cx.tcx.sess.target.simd_types_indirect =>
+                    if abi != SpecAbi::RustIntrinsic && cx.tcx.sess.target.simd_types_indirect =>
                 {
                     arg.make_indirect();
                     return;
diff --git a/compiler/stable_mir/src/ty.rs b/compiler/stable_mir/src/ty.rs
index 658e8aa28b5..ed4a4290246 100644
--- a/compiler/stable_mir/src/ty.rs
+++ b/compiler/stable_mir/src/ty.rs
@@ -906,7 +906,6 @@ pub enum Abi {
     System { unwind: bool },
     RustIntrinsic,
     RustCall,
-    PlatformIntrinsic,
     Unadjusted,
     RustCold,
     RiscvInterruptM,
diff --git a/library/core/src/intrinsics/simd.rs b/library/core/src/intrinsics/simd.rs
index d8a1ad778d7..2eaca3b6fe4 100644
--- a/library/core/src/intrinsics/simd.rs
+++ b/library/core/src/intrinsics/simd.rs
@@ -2,7 +2,11 @@
 //!
 //! In this module, a "vector" is any `repr(simd)` type.
 
-extern "platform-intrinsic" {
+// Temporary macro while we switch the ABI from "platform-intrinsics" to "intrinsics".
+#[rustfmt::skip]
+macro_rules! declare_intrinsics {
+($abi:tt) => {
+extern $abi {
     /// Insert an element into a vector, returning the updated vector.
     ///
     /// `T` must be a vector with element type `U`.
@@ -10,6 +14,7 @@ extern "platform-intrinsic" {
     /// # Safety
     ///
     /// `idx` must be in-bounds of the vector.
+    #[rustc_nounwind]
     pub fn simd_insert<T, U>(x: T, idx: u32, val: U) -> T;
 
     /// Extract an element from a vector.
@@ -19,21 +24,25 @@ extern "platform-intrinsic" {
     /// # Safety
     ///
     /// `idx` must be in-bounds of the vector.
+    #[rustc_nounwind]
     pub fn simd_extract<T, U>(x: T, idx: u32) -> U;
 
     /// Add two simd vectors elementwise.
     ///
     /// `T` must be a vector of integer or floating point primitive types.
+    #[rustc_nounwind]
     pub fn simd_add<T>(x: T, y: T) -> T;
 
     /// Subtract `rhs` from `lhs` elementwise.
     ///
     /// `T` must be a vector of integer or floating point primitive types.
+    #[rustc_nounwind]
     pub fn simd_sub<T>(lhs: T, rhs: T) -> T;
 
     /// Multiply two simd vectors elementwise.
     ///
     /// `T` must be a vector of integer or floating point primitive types.
+    #[rustc_nounwind]
     pub fn simd_mul<T>(x: T, y: T) -> T;
 
     /// Divide `lhs` by `rhs` elementwise.
@@ -43,6 +52,7 @@ extern "platform-intrinsic" {
     /// # Safety
     /// For integers, `rhs` must not contain any zero elements.
     /// Additionally for signed integers, `<int>::MIN / -1` is undefined behavior.
+    #[rustc_nounwind]
     pub fn simd_div<T>(lhs: T, rhs: T) -> T;
 
     /// Remainder of two vectors elementwise
@@ -52,6 +62,7 @@ extern "platform-intrinsic" {
     /// # Safety
     /// For integers, `rhs` must not contain any zero elements.
     /// Additionally for signed integers, `<int>::MIN / -1` is undefined behavior.
+    #[rustc_nounwind]
     pub fn simd_rem<T>(lhs: T, rhs: T) -> T;
 
     /// Elementwise vector left shift, with UB on overflow.
@@ -63,6 +74,7 @@ extern "platform-intrinsic" {
     /// # Safety
     ///
     /// Each element of `rhs` must be less than `<int>::BITS`.
+    #[rustc_nounwind]
     pub fn simd_shl<T>(lhs: T, rhs: T) -> T;
 
     /// Elementwise vector right shift, with UB on overflow.
@@ -74,21 +86,25 @@ extern "platform-intrinsic" {
     /// # Safety
     ///
     /// Each element of `rhs` must be less than `<int>::BITS`.
+    #[rustc_nounwind]
     pub fn simd_shr<T>(lhs: T, rhs: T) -> T;
 
     /// Elementwise vector "and".
     ///
     /// `T` must be a vector of integer primitive types.
+    #[rustc_nounwind]
     pub fn simd_and<T>(x: T, y: T) -> T;
 
     /// Elementwise vector "or".
     ///
     /// `T` must be a vector of integer primitive types.
+    #[rustc_nounwind]
     pub fn simd_or<T>(x: T, y: T) -> T;
 
     /// Elementwise vector "exclusive or".
     ///
     /// `T` must be a vector of integer primitive types.
+    #[rustc_nounwind]
     pub fn simd_xor<T>(x: T, y: T) -> T;
 
     /// Numerically cast a vector, elementwise.
@@ -109,6 +125,7 @@ extern "platform-intrinsic" {
     /// * Not be `NaN`
     /// * Not be infinite
     /// * Be representable in the return type, after truncating off its fractional part
+    #[rustc_nounwind]
     pub fn simd_cast<T, U>(x: T) -> U;
 
     /// Numerically cast a vector, elementwise.
@@ -122,6 +139,7 @@ extern "platform-intrinsic" {
     /// When casting floats to integers, the result is truncated.
     /// When casting integers to floats, the result is rounded.
     /// Otherwise, truncates or extends the value, maintaining the sign for signed integers.
+    #[rustc_nounwind]
     pub fn simd_as<T, U>(x: T) -> U;
 
     /// Elementwise negation of a vector.
@@ -129,11 +147,13 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// Rust panics for `-<int>::Min` due to overflow, but it is not UB with this intrinsic.
+    #[rustc_nounwind]
     pub fn simd_neg<T>(x: T) -> T;
 
     /// Elementwise absolute value of a vector.
     ///
     /// `T` must be a vector of floating-point primitive types.
+    #[rustc_nounwind]
     pub fn simd_fabs<T>(x: T) -> T;
 
     /// Elementwise minimum of a vector.
@@ -141,6 +161,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of floating-point primitive types.
     ///
     /// Follows IEEE-754 `minNum` semantics.
+    #[rustc_nounwind]
     pub fn simd_fmin<T>(x: T, y: T) -> T;
 
     /// Elementwise maximum of a vector.
@@ -148,6 +169,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of floating-point primitive types.
     ///
     /// Follows IEEE-754 `maxNum` semantics.
+    #[rustc_nounwind]
     pub fn simd_fmax<T>(x: T, y: T) -> T;
 
     /// Tests elementwise equality of two vectors.
@@ -157,6 +179,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_eq<T, U>(x: T, y: T) -> U;
 
     /// Tests elementwise inequality equality of two vectors.
@@ -166,6 +189,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_ne<T, U>(x: T, y: T) -> U;
 
     /// Tests if `x` is less than `y`, elementwise.
@@ -175,6 +199,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_lt<T, U>(x: T, y: T) -> U;
 
     /// Tests if `x` is less than or equal to `y`, elementwise.
@@ -184,6 +209,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_le<T, U>(x: T, y: T) -> U;
 
     /// Tests if `x` is greater than `y`, elementwise.
@@ -193,6 +219,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_gt<T, U>(x: T, y: T) -> U;
 
     /// Tests if `x` is greater than or equal to `y`, elementwise.
@@ -202,6 +229,7 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of integers with the same number of elements and element size as `T`.
     ///
     /// Returns `0` for false and `!0` for true.
+    #[rustc_nounwind]
     pub fn simd_ge<T, U>(x: T, y: T) -> U;
 
     /// Shuffle two vectors by const indices.
@@ -216,6 +244,7 @@ extern "platform-intrinsic" {
     /// Returns a new vector such that element `i` is selected from `xy[idx[i]]`, where `xy`
     /// is the concatenation of `x` and `y`. It is a compile-time error if `idx[i]` is out-of-bounds
     /// of `xy`.
+    #[rustc_nounwind]
     pub fn simd_shuffle<T, U, V>(x: T, y: T, idx: U) -> V;
 
     /// Shuffle two vectors by const indices.
@@ -227,6 +256,7 @@ extern "platform-intrinsic" {
     /// Returns a new vector such that element `i` is selected from `xy[IDX[i]]`, where `xy`
     /// is the concatenation of `x` and `y`. It is a compile-time error if `IDX[i]` is out-of-bounds
     /// of `xy`.
+    #[rustc_nounwind]
     pub fn simd_shuffle_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;
 
     /// Read a vector of pointers.
@@ -249,6 +279,7 @@ extern "platform-intrinsic" {
     /// type).
     ///
     /// `mask` must only contain `0` or `!0` values.
+    #[rustc_nounwind]
     pub fn simd_gather<T, U, V>(val: T, ptr: U, mask: V) -> T;
 
     /// Write to a vector of pointers.
@@ -271,6 +302,7 @@ extern "platform-intrinsic" {
     /// type).
     ///
     /// `mask` must only contain `0` or `!0` values.
+    #[rustc_nounwind]
     pub fn simd_scatter<T, U, V>(val: T, ptr: U, mask: V);
 
     /// Read a vector of pointers.
@@ -292,6 +324,7 @@ extern "platform-intrinsic" {
     /// type).
     ///
     /// `mask` must only contain `0` or `!0` values.
+    #[rustc_nounwind]
     pub fn simd_masked_load<V, U, T>(mask: V, ptr: U, val: T) -> T;
 
     /// Write to a vector of pointers.
@@ -312,11 +345,13 @@ extern "platform-intrinsic" {
     /// type).
     ///
     /// `mask` must only contain `0` or `!0` values.
+    #[rustc_nounwind]
     pub fn simd_masked_store<V, U, T>(mask: V, ptr: U, val: T);
 
     /// Add two simd vectors elementwise, with saturation.
     ///
     /// `T` must be a vector of integer primitive types.
+    #[rustc_nounwind]
     pub fn simd_saturating_add<T>(x: T, y: T) -> T;
 
     /// Subtract two simd vectors elementwise, with saturation.
@@ -324,6 +359,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer primitive types.
     ///
     /// Subtract `rhs` from `lhs`.
+    #[rustc_nounwind]
     pub fn simd_saturating_sub<T>(lhs: T, rhs: T) -> T;
 
     /// Add elements within a vector from left to right.
@@ -333,6 +369,7 @@ extern "platform-intrinsic" {
     /// `U` must be the element type of `T`.
     ///
     /// Starting with the value `y`, add the elements of `x` and accumulate.
+    #[rustc_nounwind]
     pub fn simd_reduce_add_ordered<T, U>(x: T, y: U) -> U;
 
     /// Add elements within a vector in arbitrary order. May also be re-associated with
@@ -341,6 +378,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// `U` must be the element type of `T`.
+    #[rustc_nounwind]
     pub fn simd_reduce_add_unordered<T, U>(x: T) -> U;
 
     /// Multiply elements within a vector from left to right.
@@ -350,6 +388,7 @@ extern "platform-intrinsic" {
     /// `U` must be the element type of `T`.
     ///
     /// Starting with the value `y`, multiply the elements of `x` and accumulate.
+    #[rustc_nounwind]
     pub fn simd_reduce_mul_ordered<T, U>(x: T, y: U) -> U;
 
     /// Add elements within a vector in arbitrary order. May also be re-associated with
@@ -358,6 +397,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// `U` must be the element type of `T`.
+    #[rustc_nounwind]
     pub fn simd_reduce_mul_unordered<T, U>(x: T) -> U;
 
     /// Check if all mask values are true.
@@ -366,6 +406,7 @@ extern "platform-intrinsic" {
     ///
     /// # Safety
     /// `x` must contain only `0` or `!0`.
+    #[rustc_nounwind]
     pub fn simd_reduce_all<T>(x: T) -> bool;
 
     /// Check if all mask values are true.
@@ -374,6 +415,7 @@ extern "platform-intrinsic" {
     ///
     /// # Safety
     /// `x` must contain only `0` or `!0`.
+    #[rustc_nounwind]
     pub fn simd_reduce_any<T>(x: T) -> bool;
 
     /// Return the maximum element of a vector.
@@ -383,6 +425,7 @@ extern "platform-intrinsic" {
     /// `U` must be the element type of `T`.
     ///
     /// For floating-point values, uses IEEE-754 `maxNum`.
+    #[rustc_nounwind]
     pub fn simd_reduce_max<T, U>(x: T) -> U;
 
     /// Return the minimum element of a vector.
@@ -392,6 +435,7 @@ extern "platform-intrinsic" {
     /// `U` must be the element type of `T`.
     ///
     /// For floating-point values, uses IEEE-754 `minNum`.
+    #[rustc_nounwind]
     pub fn simd_reduce_min<T, U>(x: T) -> U;
 
     /// Logical "and" all elements together.
@@ -399,6 +443,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// `U` must be the element type of `T`.
+    #[rustc_nounwind]
     pub fn simd_reduce_and<T, U>(x: T) -> U;
 
     /// Logical "or" all elements together.
@@ -406,6 +451,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// `U` must be the element type of `T`.
+    #[rustc_nounwind]
     pub fn simd_reduce_or<T, U>(x: T) -> U;
 
     /// Logical "exclusive or" all elements together.
@@ -413,6 +459,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of integer or floating-point primitive types.
     ///
     /// `U` must be the element type of `T`.
+    #[rustc_nounwind]
     pub fn simd_reduce_xor<T, U>(x: T) -> U;
 
     /// Truncate an integer vector to a bitmask.
@@ -441,6 +488,7 @@ extern "platform-intrinsic" {
     ///
     /// # Safety
     /// `x` must contain only `0` and `!0`.
+    #[rustc_nounwind]
     pub fn simd_bitmask<T, U>(x: T) -> U;
 
     /// Select elements from a mask.
@@ -455,6 +503,7 @@ extern "platform-intrinsic" {
     ///
     /// # Safety
     /// `mask` must only contain `0` and `!0`.
+    #[rustc_nounwind]
     pub fn simd_select<M, T>(mask: M, if_true: T, if_false: T) -> T;
 
     /// Select elements from a bitmask.
@@ -471,6 +520,7 @@ extern "platform-intrinsic" {
     ///
     /// # Safety
     /// Padding bits must be all zero.
+    #[rustc_nounwind]
     pub fn simd_select_bitmask<M, T>(m: M, yes: T, no: T) -> T;
 
     /// Elementwise calculates the offset from a pointer vector, potentially wrapping.
@@ -480,11 +530,13 @@ extern "platform-intrinsic" {
     /// `U` must be a vector of `isize` or `usize` with the same number of elements as `T`.
     ///
     /// Operates as if by `<ptr>::wrapping_offset`.
+    #[rustc_nounwind]
     pub fn simd_arith_offset<T, U>(ptr: T, offset: U) -> T;
 
     /// Cast a vector of pointers.
     ///
     /// `T` and `U` must be vectors of pointers with the same number of elements.
+    #[rustc_nounwind]
     pub fn simd_cast_ptr<T, U>(ptr: T) -> U;
 
     /// Expose a vector of pointers as a vector of addresses.
@@ -492,6 +544,7 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of pointers.
     ///
     /// `U` must be a vector of `usize` with the same length as `T`.
+    #[rustc_nounwind]
     pub fn simd_expose_addr<T, U>(ptr: T) -> U;
 
     /// Create a vector of pointers from a vector of addresses.
@@ -499,92 +552,117 @@ extern "platform-intrinsic" {
     /// `T` must be a vector of `usize`.
     ///
     /// `U` must be a vector of pointers, with the same length as `T`.
+    #[rustc_nounwind]
     pub fn simd_from_exposed_addr<T, U>(addr: T) -> U;
 
     /// Swap bytes of each element.
     ///
     /// `T` must be a vector of integers.
+    #[rustc_nounwind]
     pub fn simd_bswap<T>(x: T) -> T;
 
     /// Reverse bits of each element.
     ///
     /// `T` must be a vector of integers.
+    #[rustc_nounwind]
     pub fn simd_bitreverse<T>(x: T) -> T;
 
     /// Count the leading zeros of each element.
     ///
     /// `T` must be a vector of integers.
+    #[rustc_nounwind]
     pub fn simd_ctlz<T>(x: T) -> T;
 
     /// Count the trailing zeros of each element.
     ///
     /// `T` must be a vector of integers.
+    #[rustc_nounwind]
     pub fn simd_cttz<T>(x: T) -> T;
 
     /// Round up each element to the next highest integer-valued float.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_ceil<T>(x: T) -> T;
 
     /// Round down each element to the next lowest integer-valued float.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_floor<T>(x: T) -> T;
 
     /// Round each element to the closest integer-valued float.
     /// Ties are resolved by rounding away from 0.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_round<T>(x: T) -> T;
 
     /// Return the integer part of each element as an integer-valued float.
     /// In other words, non-integer values are truncated towards zero.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_trunc<T>(x: T) -> T;
 
     /// Takes the square root of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fsqrt<T>(x: T) -> T;
 
     /// Computes `(x*y) + z` for each element, but without any intermediate rounding.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fma<T>(x: T, y: T, z: T) -> T;
 
     // Computes the sine of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fsin<T>(a: T) -> T;
 
     // Computes the cosine of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fcos<T>(a: T) -> T;
 
     // Computes the exponential function of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fexp<T>(a: T) -> T;
 
     // Computes 2 raised to the power of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_fexp2<T>(a: T) -> T;
 
     // Computes the base 10 logarithm of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_flog10<T>(a: T) -> T;
 
     // Computes the base 2 logarithm of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_flog2<T>(a: T) -> T;
 
     // Computes the natural logarithm of each element.
     ///
     /// `T` must be a vector of floats.
+    #[rustc_nounwind]
     pub fn simd_flog<T>(a: T) -> T;
 }
+}
+}
+
+#[cfg(bootstrap)]
+declare_intrinsics!("platform-intrinsic");
+#[cfg(not(bootstrap))]
+declare_intrinsics!("rust-intrinsic");
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 49cead680e3..7b735d48bdf 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -202,6 +202,7 @@
 //
 // Language features:
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(platform_intrinsics))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
 #![feature(allow_internal_unsafe)]
@@ -246,7 +247,6 @@
 #![feature(never_type)]
 #![feature(no_core)]
 #![feature(no_sanitize)]
-#![feature(platform_intrinsics)]
 #![feature(prelude_import)]
 #![feature(repr_simd)]
 #![feature(rustc_allow_const_fn_unstable)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index c6cd2c6786a..288cce3aa08 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -270,6 +270,7 @@
 //
 // Language features:
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(platform_intrinsics))]
 #![feature(alloc_error_handler)]
 #![feature(allocator_internals)]
 #![feature(allow_internal_unsafe)]
@@ -301,7 +302,6 @@
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(no_sanitize)]
-#![feature(platform_intrinsics)]
 #![feature(prelude_import)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]