Auto merge of #125358 - matthiaskrgr:rollup-mx841tg, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #124570 (Miscellaneous cleanups)
 - #124772 (Refactor documentation for Apple targets)
 - #125011 (Add opt-for-size core lib feature flag)
 - #125218 (Migrate `run-make/no-intermediate-extras` to new `rmake.rs`)
 - #125225 (Use functions from `crt_externs.h` on iOS/tvOS/watchOS/visionOS)
 - #125266 (compiler: add simd_ctpop intrinsic)
 - #125348 (Small fixes to `std::path::absolute` docs)

Failed merges:

 - #125296 (Fix `unexpected_cfgs` lint on std)

r? `@ghost`
`@rustbot` modify labels: rollup

42 files changed, 680 insertions, 439 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
index 452b5988dab..b17f191ce26 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs
@@ -348,6 +348,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
         | sym::simd_bswap
         | sym::simd_bitreverse
         | sym::simd_ctlz
+        | sym::simd_ctpop
         | sym::simd_cttz => {
             intrinsic_args!(fx, args => (a); intrinsic);
 
@@ -367,6 +368,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 (ty::Uint(_) | ty::Int(_), sym::simd_bswap) => fx.bcx.ins().bswap(lane),
                 (ty::Uint(_) | ty::Int(_), sym::simd_bitreverse) => fx.bcx.ins().bitrev(lane),
                 (ty::Uint(_) | ty::Int(_), sym::simd_ctlz) => fx.bcx.ins().clz(lane),
+                (ty::Uint(_) | ty::Int(_), sym::simd_ctpop) => fx.bcx.ins().popcnt(lane),
                 (ty::Uint(_) | ty::Int(_), sym::simd_cttz) => fx.bcx.ins().ctz(lane),
 
                 _ => unreachable!(),
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index c0a1208a8c7..80e863af893 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -2336,7 +2336,10 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
     }
 
     // Unary integer intrinsics
-    if matches!(name, sym::simd_bswap | sym::simd_bitreverse | sym::simd_ctlz | sym::simd_cttz) {
+    if matches!(
+        name,
+        sym::simd_bswap | sym::simd_bitreverse | sym::simd_ctlz | sym::simd_ctpop | sym::simd_cttz
+    ) {
         let vec_ty = bx.cx.type_vector(
             match *in_elem.kind() {
                 ty::Int(i) => bx.cx.type_int_from_ty(i),
@@ -2354,31 +2357,38 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
             sym::simd_bswap => "bswap",
             sym::simd_bitreverse => "bitreverse",
             sym::simd_ctlz => "ctlz",
+            sym::simd_ctpop => "ctpop",
             sym::simd_cttz => "cttz",
             _ => unreachable!(),
         };
         let int_size = in_elem.int_size_and_signed(bx.tcx()).0.bits();
         let llvm_intrinsic = &format!("llvm.{}.v{}i{}", intrinsic_name, in_len, int_size,);
 
-        return if name == sym::simd_bswap && int_size == 8 {
+        return match name {
             // byte swap is no-op for i8/u8
-            Ok(args[0].immediate())
-        } else if matches!(name, sym::simd_ctlz | sym::simd_cttz) {
-            let fn_ty = bx.type_func(&[vec_ty, bx.type_i1()], vec_ty);
-            let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
-            Ok(bx.call(
-                fn_ty,
-                None,
-                None,
-                f,
-                &[args[0].immediate(), bx.const_int(bx.type_i1(), 0)],
-                None,
-                None,
-            ))
-        } else {
-            let fn_ty = bx.type_func(&[vec_ty], vec_ty);
-            let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
-            Ok(bx.call(fn_ty, None, None, f, &[args[0].immediate()], None, None))
+            sym::simd_bswap if int_size == 8 => Ok(args[0].immediate()),
+            sym::simd_ctlz | sym::simd_cttz => {
+                // for the (int, i1 immediate) pair, the second arg adds `(0, true) => poison`
+                let fn_ty = bx.type_func(&[vec_ty, bx.type_i1()], vec_ty);
+                let dont_poison_on_zero = bx.const_int(bx.type_i1(), 0);
+                let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+                Ok(bx.call(
+                    fn_ty,
+                    None,
+                    None,
+                    f,
+                    &[args[0].immediate(), dont_poison_on_zero],
+                    None,
+                    None,
+                ))
+            }
+            sym::simd_bswap | sym::simd_bitreverse | sym::simd_ctpop => {
+                // simple unary argument cases
+                let fn_ty = bx.type_func(&[vec_ty], vec_ty);
+                let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+                Ok(bx.call(fn_ty, None, None, f, &[args[0].immediate()], None, None))
+            }
+            _ => unreachable!(),
         };
     }
 
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index a525b838afa..7b293e2b533 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -1,9 +1,3 @@
-/*!
-
-Rust MIR: a lowered representation of Rust.
-
-*/
-
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![feature(rustdoc_internals)]
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index d829e720d9e..50fe20346cf 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -607,6 +607,7 @@ pub fn check_intrinsic_type(
             | sym::simd_bitreverse
             | sym::simd_ctlz
             | sym::simd_cttz
+            | sym::simd_ctpop
             | sym::simd_fsqrt
             | sym::simd_fsin
             | sym::simd_fcos
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 99584845e49..00bb4c435c8 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -1,21 +1,22 @@
+// tidy-alphabetical-start
+#![allow(internal_features)]
+#![allow(rustc::potential_query_instability)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
-#![feature(rustdoc_internals)]
-#![allow(internal_features)]
+#![feature(coroutines)]
 #![feature(decl_macro)]
 #![feature(error_iter)]
 #![feature(extract_if)]
-#![feature(coroutines)]
+#![feature(if_let_guard)]
 #![feature(iter_from_coroutine)]
 #![feature(let_chains)]
-#![feature(if_let_guard)]
-#![feature(proc_macro_internals)]
 #![feature(macro_metavar_expr)]
 #![feature(min_specialization)]
-#![feature(trusted_len)]
-#![feature(try_blocks)]
 #![feature(never_type)]
-#![allow(rustc::potential_query_instability)]
+#![feature(proc_macro_internals)]
+#![feature(rustdoc_internals)]
+#![feature(trusted_len)]
+// tidy-alphabetical-end
 
 extern crate proc_macro;
 
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 79e4ff81093..825034cf96a 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -1,15 +1,13 @@
 use crate::creader::CrateMetadataRef;
-use decoder::Metadata;
+pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
+use decoder::{DecodeContext, Metadata};
 use def_path_hash_map::DefPathHashMapRef;
-use rustc_data_structures::fx::FxHashMap;
-use rustc_macros::{Decodable, Encodable, TyDecodable, TyEncodable};
-use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
-use rustc_middle::middle::lib_features::FeatureStability;
-use table::TableBuilder;
-
+use encoder::EncodeContext;
+pub use encoder::{encode_metadata, rendered_const, EncodedMetadata};
 use rustc_ast as ast;
 use rustc_ast::expand::StrippedCfgItem;
 use rustc_attr as attr;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::svh::Svh;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap};
@@ -18,10 +16,13 @@ use rustc_hir::definitions::DefKey;
 use rustc_hir::lang_items::LangItem;
 use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
+use rustc_macros::{Decodable, Encodable, TyDecodable, TyEncodable};
 use rustc_macros::{MetadataDecodable, MetadataEncodable};
 use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
+use rustc_middle::middle::lib_features::FeatureStability;
 use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::mir;
 use rustc_middle::trivially_parameterized_over_tcx;
@@ -33,20 +34,14 @@ use rustc_serialize::opaque::FileEncoder;
 use rustc_session::config::SymbolManglingVersion;
 use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
 use rustc_span::edition::Edition;
-use rustc_span::hygiene::{ExpnIndex, MacroKind};
+use rustc_span::hygiene::{ExpnIndex, MacroKind, SyntaxContextData};
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::{self, ExpnData, ExpnHash, ExpnId, Span};
 use rustc_target::abi::{FieldIdx, VariantIdx};
 use rustc_target::spec::{PanicStrategy, TargetTriple};
-
 use std::marker::PhantomData;
 use std::num::NonZero;
-
-use decoder::DecodeContext;
-pub(crate) use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
-use encoder::EncodeContext;
-pub use encoder::{encode_metadata, rendered_const, EncodedMetadata};
-use rustc_span::hygiene::SyntaxContextData;
+use table::TableBuilder;
 
 mod decoder;
 mod def_path_hash_map;
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 04fd4c8d0f7..70437fdcb6f 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -22,46 +22,46 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// tidy-alphabetical-start
+#![allow(internal_features)]
+#![allow(rustc::diagnostic_outside_of_impl)]
+#![allow(rustc::potential_query_instability)]
+#![allow(rustc::untranslatable_diagnostic)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
-#![feature(min_exhaustive_patterns)]
-#![feature(rustdoc_internals)]
 #![feature(allocator_api)]
 #![feature(array_windows)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(closure_track_caller)]
-#![feature(core_intrinsics)]
+#![feature(const_option)]
 #![feature(const_type_name)]
-#![feature(discriminant_kind)]
+#![feature(core_intrinsics)]
 #![feature(coroutines)]
-#![feature(stmt_expr_attributes)]
+#![feature(decl_macro)]
+#![feature(discriminant_kind)]
+#![feature(extern_types)]
+#![feature(extract_if)]
 #![feature(if_let_guard)]
+#![feature(intra_doc_pointers)]
 #![feature(iter_from_coroutine)]
+#![feature(let_chains)]
+#![feature(macro_metavar_expr)]
+#![feature(min_exhaustive_patterns)]
+#![feature(min_specialization)]
 #![feature(negative_impls)]
 #![feature(never_type)]
-#![feature(extern_types)]
 #![feature(new_uninit)]
-#![feature(let_chains)]
-#![feature(min_specialization)]
-#![feature(trusted_len)]
-#![feature(type_alias_impl_trait)]
-#![feature(strict_provenance)]
+#![feature(ptr_alignment_type)]
 #![feature(rustc_attrs)]
-#![feature(control_flow_enum)]
+#![feature(rustdoc_internals)]
+#![feature(strict_provenance)]
 #![feature(trait_upcasting)]
+#![feature(trusted_len)]
 #![feature(try_blocks)]
-#![feature(decl_macro)]
-#![feature(extract_if)]
-#![feature(intra_doc_pointers)]
+#![feature(type_alias_impl_trait)]
 #![feature(yeet_expr)]
-#![feature(const_option)]
-#![feature(ptr_alignment_type)]
-#![feature(macro_metavar_expr)]
-#![allow(internal_features)]
-#![allow(rustc::potential_query_instability)]
-#![allow(rustc::diagnostic_outside_of_impl)]
-#![allow(rustc::untranslatable_diagnostic)]
+// tidy-alphabetical-end
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index aadbd747313..b1438a542ac 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -42,12 +42,9 @@ use std::collections::hash_map::Entry;
 
 #[derive(LintDiagnostic)]
 #[diag(passes_diagnostic_diagnostic_on_unimplemented_only_for_traits)]
-pub struct DiagnosticOnUnimplementedOnlyForTraits;
+struct DiagnosticOnUnimplementedOnlyForTraits;
 
-pub(crate) fn target_from_impl_item<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    impl_item: &hir::ImplItem<'_>,
-) -> Target {
+fn target_from_impl_item<'tcx>(tcx: TyCtxt<'tcx>, impl_item: &hir::ImplItem<'_>) -> Target {
     match impl_item.kind {
         hir::ImplItemKind::Const(..) => Target::AssocConst,
         hir::ImplItemKind::Fn(..) => {
@@ -99,7 +96,7 @@ struct CheckAttrVisitor<'tcx> {
 }
 
 impl<'tcx> CheckAttrVisitor<'tcx> {
-    pub fn dcx(&self) -> &'tcx DiagCtxt {
+    fn dcx(&self) -> &'tcx DiagCtxt {
         self.tcx.dcx()
     }
 
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index a5fa94faead..b3722e99e16 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -149,8 +149,9 @@ impl<'ast, 'tcx> LanguageItemCollector<'ast, 'tcx> {
                 }
             };
 
-            // When there's a duplicate lang item, something went very wrong and there's no value in recovering or doing anything.
-            // Give the user the one message to let them debug the mess they created and then wish them farewell.
+            // When there's a duplicate lang item, something went very wrong and there's no value
+            // in recovering or doing anything. Give the user the one message to let them debug the
+            // mess they created and then wish them farewell.
             self.tcx.dcx().emit_fatal(DuplicateLangItem {
                 local_span: item_span,
                 lang_item_name,
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 1869daf7e12..ace4dff46aa 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1682,6 +1682,7 @@ symbols! {
         simd_cast_ptr,
         simd_ceil,
         simd_ctlz,
+        simd_ctpop,
         simd_cttz,
         simd_div,
         simd_eq,
diff --git a/compiler/rustc_target/src/spec/base/apple/mod.rs b/compiler/rustc_target/src/spec/base/apple/mod.rs
index c5b2065080b..05542009083 100644
--- a/compiler/rustc_target/src/spec/base/apple/mod.rs
+++ b/compiler/rustc_target/src/spec/base/apple/mod.rs
@@ -272,6 +272,7 @@ fn macos_default_deployment_target(arch: Arch) -> (u32, u32) {
 
 fn macos_deployment_target(arch: Arch) -> (u32, u32) {
     // If you are looking for the default deployment target, prefer `rustc --print deployment-target`.
+    // Note: If bumping this version, remember to update it in the rustc/platform-support docs.
     from_set_deployment_target("MACOSX_DEPLOYMENT_TARGET")
         .unwrap_or_else(|| macos_default_deployment_target(arch))
 }
@@ -320,6 +321,7 @@ fn link_env_remove(os: &'static str) -> StaticCow<[StaticCow<str>]> {
 
 fn ios_deployment_target(arch: Arch, abi: &str) -> (u32, u32) {
     // If you are looking for the default deployment target, prefer `rustc --print deployment-target`.
+    // Note: If bumping this version, remember to update it in the rustc/platform-support docs.
     let (major, minor) = match (arch, abi) {
         (Arm64e, _) => (14, 0),
         // Mac Catalyst defaults to 13.1 in Clang.
@@ -352,6 +354,7 @@ pub fn ios_sim_llvm_target(arch: Arch) -> String {
 
 fn tvos_deployment_target() -> (u32, u32) {
     // If you are looking for the default deployment target, prefer `rustc --print deployment-target`.
+    // Note: If bumping this version, remember to update it in the rustc platform-support docs.
     from_set_deployment_target("TVOS_DEPLOYMENT_TARGET").unwrap_or((10, 0))
 }
 
@@ -367,6 +370,7 @@ pub fn tvos_sim_llvm_target(arch: Arch) -> String {
 
 fn watchos_deployment_target() -> (u32, u32) {
     // If you are looking for the default deployment target, prefer `rustc --print deployment-target`.
+    // Note: If bumping this version, remember to update it in the rustc platform-support docs.
     from_set_deployment_target("WATCHOS_DEPLOYMENT_TARGET").unwrap_or((5, 0))
 }
 
@@ -382,6 +386,7 @@ pub fn watchos_sim_llvm_target(arch: Arch) -> String {
 
 fn visionos_deployment_target() -> (u32, u32) {
     // If you are looking for the default deployment target, prefer `rustc --print deployment-target`.
+    // Note: If bumping this version, remember to update it in the rustc platform-support docs.
     from_set_deployment_target("XROS_DEPLOYMENT_TARGET").unwrap_or((1, 0))
 }
 
diff --git a/library/alloc/Cargo.toml b/library/alloc/Cargo.toml
index e8afed6b35a..2e7fcb9dbd3 100644
--- a/library/alloc/Cargo.toml
+++ b/library/alloc/Cargo.toml
@@ -37,4 +37,6 @@ compiler-builtins-no-asm = ["compiler_builtins/no-asm"]
 compiler-builtins-mangled-names = ["compiler_builtins/mangled-names"]
 compiler-builtins-weak-intrinsics = ["compiler_builtins/weak-intrinsics"]
 # Make panics and failed asserts immediately abort without formatting any message
-panic_immediate_abort = []
+panic_immediate_abort = ["core/panic_immediate_abort"]
+# Choose algorithms that are optimized for binary size instead of runtime performance
+optimize_for_size = ["core/optimize_for_size"]
diff --git a/library/core/Cargo.toml b/library/core/Cargo.toml
index a02fcf50416..11d33971f25 100644
--- a/library/core/Cargo.toml
+++ b/library/core/Cargo.toml
@@ -31,6 +31,8 @@ rand_xorshift = { version = "0.3.0", default-features = false }
 [features]
 # Make panics and failed asserts immediately abort without formatting any message
 panic_immediate_abort = []
+# Choose algorithms that are optimized for binary size instead of runtime performance
+optimize_for_size = []
 # Make `RefCell` store additional debugging information, which is printed out when
 # a borrow error occurs
 debug_refcell = []
diff --git a/library/core/src/intrinsics/simd.rs b/library/core/src/intrinsics/simd.rs
index ceea6790129..d1be534eaf0 100644
--- a/library/core/src/intrinsics/simd.rs
+++ b/library/core/src/intrinsics/simd.rs
@@ -569,6 +569,13 @@ extern "rust-intrinsic" {
     #[rustc_nounwind]
     pub fn simd_ctlz<T>(x: T) -> T;
 
+    /// Count the number of ones in each element.
+    ///
+    /// `T` must be a vector of integers.
+    #[rustc_nounwind]
+    #[cfg(not(bootstrap))]
+    pub fn simd_ctpop<T>(x: T) -> T;
+
     /// Count the trailing zeros of each element.
     ///
     /// `T` must be a vector of integers.
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index a77d438e1f1..5b36867fe24 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -78,6 +78,8 @@ system-llvm-libunwind = ["unwind/system-llvm-libunwind"]
 
 # Make panics and failed asserts immediately abort without formatting any message
 panic_immediate_abort = ["core/panic_immediate_abort", "alloc/panic_immediate_abort"]
+# Choose algorithms that are optimized for binary size instead of runtime performance
+optimize_for_size = ["core/optimize_for_size", "alloc/optimize_for_size"]
 
 # Enable std_detect default features for stdarch/crates/std_detect:
 # https://github.com/rust-lang/stdarch/blob/master/crates/std_detect/Cargo.toml
diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index 79d800ff072..f835b69f0cf 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -3323,7 +3323,7 @@ impl Error for StripPrefixError {
 ///
 /// # Examples
 ///
-/// ## Posix paths
+/// ## POSIX paths
 ///
 /// ```
 /// # #[cfg(unix)]
@@ -3369,9 +3369,12 @@ impl Error for StripPrefixError {
 /// ```
 ///
 /// For verbatim paths this will simply return the path as given. For other
-/// paths this is currently equivalent to calling [`GetFullPathNameW`][windows-path]
-/// This may change in the future.
+/// paths this is currently equivalent to calling
+/// [`GetFullPathNameW`][windows-path].
 ///
+/// Note that this [may change in the future][changes].
+///
+/// [changes]: io#platform-specific-behavior
 /// [posix-semantics]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
 /// [windows-path]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfullpathnamew
 #[stable(feature = "absolute_path", since = "1.79.0")]
diff --git a/library/std/src/sys/pal/unix/args.rs b/library/std/src/sys/pal/unix/args.rs
index 2a3298e8b4c..db2ec73148e 100644
--- a/library/std/src/sys/pal/unix/args.rs
+++ b/library/std/src/sys/pal/unix/args.rs
@@ -5,8 +5,9 @@
 
 #![allow(dead_code)] // runtime init functions not used during testing
 
-use crate::ffi::OsString;
+use crate::ffi::{CStr, OsString};
 use crate::fmt;
+use crate::os::unix::ffi::OsStringExt;
 use crate::vec;
 
 /// One-time global initialization.
@@ -16,7 +17,46 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 
 /// Returns the command line arguments
 pub fn args() -> Args {
-    imp::args()
+    let (argc, argv) = imp::argc_argv();
+
+    let mut vec = Vec::with_capacity(argc as usize);
+
+    for i in 0..argc {
+        // SAFETY: `argv` is non-null if `argc` is positive, and it is
+        // guaranteed to be at least as long as `argc`, so reading from it
+        // should be safe.
+        let ptr = unsafe { argv.offset(i).read() };
+
+        // Some C commandline parsers (e.g. GLib and Qt) are replacing already
+        // handled arguments in `argv` with `NULL` and move them to the end.
+        //
+        // Since they can't directly ensure updates to `argc` as well, this
+        // means that `argc` might be bigger than the actual number of
+        // non-`NULL` pointers in `argv` at this point.
+        //
+        // To handle this we simply stop iterating at the first `NULL`
+        // argument. `argv` is also guaranteed to be `NULL`-terminated so any
+        // non-`NULL` arguments after the first `NULL` can safely be ignored.
+        if ptr.is_null() {
+            // NOTE: On Apple platforms, `-[NSProcessInfo arguments]` does not
+            // stop iterating here, but instead `continue`, always iterating
+            // up until it reached `argc`.
+            //
+            // This difference will only matter in very specific circumstances
+            // where `argc`/`argv` have been modified, but in unexpected ways,
+            // so it likely doesn't really matter which option we choose.
+            // See the following PR for further discussion:
+            // <https://github.com/rust-lang/rust/pull/125225>
+            break;
+        }
+
+        // SAFETY: Just checked that the pointer is not NULL, and arguments
+        // are otherwise guaranteed to be valid C strings.
+        let cstr = unsafe { CStr::from_ptr(ptr) };
+        vec.push(OsStringExt::from_vec(cstr.to_bytes().to_vec()));
+    }
+
+    Args { iter: vec.into_iter() }
 }
 
 pub struct Args {
@@ -75,9 +115,7 @@ impl DoubleEndedIterator for Args {
     target_os = "hurd",
 ))]
 mod imp {
-    use super::Args;
-    use crate::ffi::{CStr, OsString};
-    use crate::os::unix::prelude::*;
+    use crate::ffi::c_char;
     use crate::ptr;
     use crate::sync::atomic::{AtomicIsize, AtomicPtr, Ordering};
 
@@ -126,162 +164,78 @@ mod imp {
         init_wrapper
     };
 
-    pub fn args() -> Args {
-        Args { iter: clone().into_iter() }
-    }
-
-    fn clone() -> Vec<OsString> {
-        unsafe {
-            // Load ARGC and ARGV, which hold the unmodified system-provided
-            // argc/argv, so we can read the pointed-to memory without atomics
-            // or synchronization.
-            //
-            // If either ARGC or ARGV is still zero or null, then either there
-            // really are no arguments, or someone is asking for `args()`
-            // before initialization has completed, and we return an empty
-            // list.
-            let argv = ARGV.load(Ordering::Relaxed);
-            let argc = if argv.is_null() { 0 } else { ARGC.load(Ordering::Relaxed) };
-            let mut args = Vec::with_capacity(argc as usize);
-            for i in 0..argc {
-                let ptr = *argv.offset(i) as *const libc::c_char;
-
-                // Some C commandline parsers (e.g. GLib and Qt) are replacing already
-                // handled arguments in `argv` with `NULL` and move them to the end. That
-                // means that `argc` might be bigger than the actual number of non-`NULL`
-                // pointers in `argv` at this point.
-                //
-                // To handle this we simply stop iterating at the first `NULL` argument.
-                //
-                // `argv` is also guaranteed to be `NULL`-terminated so any non-`NULL` arguments
-                // after the first `NULL` can safely be ignored.
-                if ptr.is_null() {
-                    break;
-                }
-
-                let cstr = CStr::from_ptr(ptr);
-                args.push(OsStringExt::from_vec(cstr.to_bytes().to_vec()));
-            }
-
-            args
-        }
+    pub fn argc_argv() -> (isize, *const *const c_char) {
+        // Load ARGC and ARGV, which hold the unmodified system-provided
+        // argc/argv, so we can read the pointed-to memory without atomics or
+        // synchronization.
+        //
+        // If either ARGC or ARGV is still zero or null, then either there
+        // really are no arguments, or someone is asking for `args()` before
+        // initialization has completed, and we return an empty list.
+        let argv = ARGV.load(Ordering::Relaxed);
+        let argc = if argv.is_null() { 0 } else { ARGC.load(Ordering::Relaxed) };
+
+        // Cast from `*mut *const u8` to `*const *const c_char`
+        (argc, argv.cast())
     }
 }
 
+// Use `_NSGetArgc` and `_NSGetArgv` on Apple platforms.
+//
+// Even though these have underscores in their names, they've been available
+// since since the first versions of both macOS and iOS, and are declared in
+// the header `crt_externs.h`.
+//
+// NOTE: This header was added to the iOS 13.0 SDK, which has been the source
+// of a great deal of confusion in the past about the availability of these
+// APIs.
+//
+// NOTE(madsmtm): This has not strictly been verified to not cause App Store
+// rejections; if this is found to be the case, the previous implementation
+// of this used `[[NSProcessInfo processInfo] arguments]`.
 #[cfg(target_vendor = "apple")]
 mod imp {
-    use super::Args;
-    use crate::ffi::CStr;
+    use crate::ffi::{c_char, c_int};
 
-    pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
-
-    #[cfg(target_os = "macos")]
-    pub fn args() -> Args {
-        use crate::os::unix::prelude::*;
-        extern "C" {
-            // These functions are in crt_externs.h.
-            fn _NSGetArgc() -> *mut libc::c_int;
-            fn _NSGetArgv() -> *mut *mut *mut libc::c_char;
-        }
-
-        let vec = unsafe {
-            let (argc, argv) =
-                (*_NSGetArgc() as isize, *_NSGetArgv() as *const *const libc::c_char);
-            (0..argc as isize)
-                .map(|i| {
-                    let bytes = CStr::from_ptr(*argv.offset(i)).to_bytes().to_vec();
-                    OsStringExt::from_vec(bytes)
-                })
-                .collect::<Vec<_>>()
-        };
-        Args { iter: vec.into_iter() }
+    pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
+        // No need to initialize anything in here, `libdyld.dylib` has already
+        // done the work for us.
     }
 
-    // As _NSGetArgc and _NSGetArgv aren't mentioned in iOS docs
-    // and use underscores in their names - they're most probably
-    // are considered private and therefore should be avoided.
-    // Here is another way to get arguments using the Objective-C
-    // runtime.
-    //
-    // In general it looks like:
-    // res = Vec::new()
-    // let args = [[NSProcessInfo processInfo] arguments]
-    // for i in (0..[args count])
-    //      res.push([args objectAtIndex:i])
-    // res
-    #[cfg(not(target_os = "macos"))]
-    pub fn args() -> Args {
-        use crate::ffi::{c_char, c_void, OsString};
-        use crate::mem;
-        use crate::str;
-
-        type Sel = *const c_void;
-        type NsId = *const c_void;
-        type NSUInteger = usize;
-
+    pub fn argc_argv() -> (isize, *const *const c_char) {
         extern "C" {
-            fn sel_registerName(name: *const c_char) -> Sel;
-            fn objc_getClass(class_name: *const c_char) -> NsId;
-
-            // This must be transmuted to an appropriate function pointer type before being called.
-            fn objc_msgSend();
-        }
-
-        const MSG_SEND_PTR: unsafe extern "C" fn() = objc_msgSend;
-        const MSG_SEND_NO_ARGUMENTS_RETURN_PTR: unsafe extern "C" fn(NsId, Sel) -> *const c_void =
-            unsafe { mem::transmute(MSG_SEND_PTR) };
-        const MSG_SEND_NO_ARGUMENTS_RETURN_NSUINTEGER: unsafe extern "C" fn(
-            NsId,
-            Sel,
-        ) -> NSUInteger = unsafe { mem::transmute(MSG_SEND_PTR) };
-        const MSG_SEND_NSINTEGER_ARGUMENT_RETURN_PTR: unsafe extern "C" fn(
-            NsId,
-            Sel,
-            NSUInteger,
-        )
-            -> *const c_void = unsafe { mem::transmute(MSG_SEND_PTR) };
-
-        let mut res = Vec::new();
-
-        unsafe {
-            let process_info_sel = sel_registerName(c"processInfo".as_ptr());
-            let arguments_sel = sel_registerName(c"arguments".as_ptr());
-            let count_sel = sel_registerName(c"count".as_ptr());
-            let object_at_index_sel = sel_registerName(c"objectAtIndex:".as_ptr());
-            let utf8string_sel = sel_registerName(c"UTF8String".as_ptr());
-
-            let klass = objc_getClass(c"NSProcessInfo".as_ptr());
-            // `+[NSProcessInfo processInfo]` returns an object with +0 retain count, so no need to manually `retain/release`.
-            let info = MSG_SEND_NO_ARGUMENTS_RETURN_PTR(klass, process_info_sel);
-
-            // `-[NSProcessInfo arguments]` returns an object with +0 retain count, so no need to manually `retain/release`.
-            let args = MSG_SEND_NO_ARGUMENTS_RETURN_PTR(info, arguments_sel);
-
-            let cnt = MSG_SEND_NO_ARGUMENTS_RETURN_NSUINTEGER(args, count_sel);
-            for i in 0..cnt {
-                // `-[NSArray objectAtIndex:]` returns an object whose lifetime is tied to the array, so no need to manually `retain/release`.
-                let ns_string =
-                    MSG_SEND_NSINTEGER_ARGUMENT_RETURN_PTR(args, object_at_index_sel, i);
-                // The lifetime of this pointer is tied to the NSString, as well as the current autorelease pool, which is why we heap-allocate the string below.
-                let utf_c_str: *const c_char =
-                    MSG_SEND_NO_ARGUMENTS_RETURN_PTR(ns_string, utf8string_sel).cast();
-                let bytes = CStr::from_ptr(utf_c_str).to_bytes();
-                res.push(OsString::from(str::from_utf8(bytes).unwrap()))
-            }
+            // These functions are in crt_externs.h.
+            fn _NSGetArgc() -> *mut c_int;
+            fn _NSGetArgv() -> *mut *mut *mut c_char;
         }
 
-        Args { iter: res.into_iter() }
+        // SAFETY: The returned pointer points to a static initialized early
+        // in the program lifetime by `libdyld.dylib`, and as such is always
+        // valid.
+        //
+        // NOTE: Similar to `_NSGetEnviron`, there technically isn't anything
+        // protecting us against concurrent modifications to this, and there
+        // doesn't exist a lock that we can take. Instead, it is generally
+        // expected that it's only modified in `main` / before other code
+        // runs, so reading this here should be fine.
+        let argc = unsafe { _NSGetArgc().read() };
+        // SAFETY: Same as above.
+        let argv = unsafe { _NSGetArgv().read() };
+
+        // Cast from `*mut *mut c_char` to `*const *const c_char`
+        (argc as isize, argv.cast())
     }
 }
 
 #[cfg(any(target_os = "espidf", target_os = "vita"))]
 mod imp {
-    use super::Args;
+    use crate::ffi::c_char;
+    use crate::ptr;
 
     #[inline(always)]
     pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
 
-    pub fn args() -> Args {
-        Args { iter: Vec::new().into_iter() }
+    pub fn argc_argv() -> (isize, *const *const c_char) {
+        (0, ptr::null())
     }
 }
diff --git a/library/std/src/sys/pal/unix/mod.rs b/library/std/src/sys/pal/unix/mod.rs
index 21f233e2262..735ed96bc7b 100644
--- a/library/std/src/sys/pal/unix/mod.rs
+++ b/library/std/src/sys/pal/unix/mod.rs
@@ -399,14 +399,13 @@ cfg_if::cfg_if! {
         // Use libumem for the (malloc-compatible) allocator
         #[link(name = "umem")]
         extern "C" {}
-    } else if #[cfg(target_os = "macos")] {
+    } else if #[cfg(target_vendor = "apple")] {
+        // Link to `libSystem.dylib`.
+        //
+        // Don't get confused by the presence of `System.framework`,
+        // it is a deprecated wrapper over the dynamic library.
         #[link(name = "System")]
         extern "C" {}
-    } else if #[cfg(all(target_vendor = "apple", not(target_os = "macos")))] {
-        #[link(name = "System")]
-        #[link(name = "objc")]
-        #[link(name = "Foundation", kind = "framework")]
-        extern "C" {}
     } else if #[cfg(target_os = "fuchsia")] {
         #[link(name = "zircon")]
         #[link(name = "fdio")]
diff --git a/library/std/src/sys/pal/unix/os.rs b/library/std/src/sys/pal/unix/os.rs
index 3a281525f8d..8afc49f5227 100644
--- a/library/std/src/sys/pal/unix/os.rs
+++ b/library/std/src/sys/pal/unix/os.rs
@@ -576,12 +576,36 @@ impl Iterator for Env {
     }
 }
 
-#[cfg(target_os = "macos")]
+// Use `_NSGetEnviron` on Apple platforms.
+//
+// `_NSGetEnviron` is the documented alternative (see `man environ`), and has
+// been available since the first versions of both macOS and iOS.
+//
+// Nowadays, specifically since macOS 10.8, `environ` has been exposed through
+// `libdyld.dylib`, which is linked via. `libSystem.dylib`:
+// <https://github.com/apple-oss-distributions/dyld/blob/dyld-1160.6/libdyld/libdyldGlue.cpp#L913>
+//
+// So in the end, it likely doesn't really matter which option we use, but the
+// performance cost of using `_NSGetEnviron` is extremely miniscule, and it
+// might be ever so slightly more supported, so let's just use that.
+//
+// NOTE: The header where this is defined (`crt_externs.h`) was added to the
+// iOS 13.0 SDK, which has been the source of a great deal of confusion in the
+// past about the availability of this API.
+//
+// NOTE(madsmtm): Neither this nor using `environ` has been verified to not
+// cause App Store rejections; if this is found to be the case, an alternative
+// implementation of this is possible using `[NSProcessInfo environment]`
+// - which internally uses `_NSGetEnviron` and a system-wide lock on the
+// environment variables to protect against `setenv`, so using that might be
+// desirable anyhow? Though it also means that we have to link to Foundation.
+#[cfg(target_vendor = "apple")]
 pub unsafe fn environ() -> *mut *const *const c_char {
     libc::_NSGetEnviron() as *mut *const *const c_char
 }
 
-#[cfg(not(target_os = "macos"))]
+// Use the `environ` static which is part of POSIX.
+#[cfg(not(target_vendor = "apple"))]
 pub unsafe fn environ() -> *mut *const *const c_char {
     extern "C" {
         static mut environ: *const *const c_char;
diff --git a/library/sysroot/Cargo.toml b/library/sysroot/Cargo.toml
index 6ff24a8db59..1ddacd92e6b 100644
--- a/library/sysroot/Cargo.toml
+++ b/library/sysroot/Cargo.toml
@@ -22,6 +22,7 @@ llvm-libunwind = ["std/llvm-libunwind"]
 system-llvm-libunwind = ["std/system-llvm-libunwind"]
 panic-unwind = ["std/panic_unwind"]
 panic_immediate_abort = ["std/panic_immediate_abort"]
+optimize_for_size = ["std/optimize_for_size"]
 profiler = ["std/profiler"]
 std_detect_file_io = ["std/std_detect_file_io"]
 std_detect_dlsym_getauxval = ["std/std_detect_dlsym_getauxval"]
diff --git a/src/ci/docker/scripts/x86_64-gnu-llvm.sh b/src/ci/docker/scripts/x86_64-gnu-llvm.sh
index 2eb751ca376..876b300d35c 100755
--- a/src/ci/docker/scripts/x86_64-gnu-llvm.sh
+++ b/src/ci/docker/scripts/x86_64-gnu-llvm.sh
@@ -23,6 +23,10 @@ if [[ -z "${PR_CI_JOB}" ]]; then
     # Run `ui-fulldeps` in `--stage=1`, which actually uses the stage0
     # compiler, and is sensitive to the addition of new flags.
     ../x.py --stage 1 test tests/ui-fulldeps
+
+    # The tests are run a second time with the size optimizations enabled.
+    ../x.py --stage 1 test library/std library/alloc library/core \
+        --rustc-args "--cfg feature=\"optimize_for_size\""
 fi
 
 # When running gcc backend tests, we need to install `libgccjit` and to not run llvm codegen
diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
index cfe4dfeb59c..6f814955857 100644
--- a/src/doc/rustc/src/SUMMARY.md
+++ b/src/doc/rustc/src/SUMMARY.md
@@ -16,13 +16,17 @@
 - [Platform Support](platform-support.md)
     - [Target Tier Policy](target-tier-policy.md)
     - [Template for Target-specific Documentation](platform-support/TEMPLATE.md)
-    - [arm64e-apple-ios.md](platform-support/arm64e-apple-ios.md)
-    - [arm64e-apple-darwin.md](platform-support/arm64e-apple-darwin.md)
-    - [aarch64-apple-ios-sim](platform-support/aarch64-apple-ios-sim.md)
     - [arm64ec-pc-windows-msvc](platform-support/arm64ec-pc-windows-msvc.md)
+    - [\*-apple-darwin](platform-support/apple-darwin.md)
+        - [i686-apple-darwin](platform-support/i686-apple-darwin.md)
+        - [x86_64h-apple-darwin](platform-support/x86_64h-apple-darwin.md)
+        - [arm64e-apple-darwin.md](platform-support/arm64e-apple-darwin.md)
+    - [\*-apple-ios](platform-support/apple-ios.md)
+        - [\*-apple-ios-macabi](platform-support/apple-ios-macabi.md)
+        - [arm64e-apple-ios.md](platform-support/arm64e-apple-ios.md)
     - [\*-apple-tvos](platform-support/apple-tvos.md)
-    - [\*-apple-watchos\*](platform-support/apple-watchos.md)
-    - [aarch64-apple-visionos\*](platform-support/apple-visionos.md)
+    - [\*-apple-watchos](platform-support/apple-watchos.md)
+    - [\*-apple-visionos](platform-support/apple-visionos.md)
     - [aarch64-nintendo-switch-freestanding](platform-support/aarch64-nintendo-switch-freestanding.md)
     - [armeb-unknown-linux-gnueabi](platform-support/armeb-unknown-linux-gnueabi.md)
     - [arm-none-eabi](platform-support/arm-none-eabi.md)
@@ -76,7 +80,6 @@
     - [x86_64-fortanix-unknown-sgx](platform-support/x86_64-fortanix-unknown-sgx.md)
     - [x86_64-unknown-linux-none.md](platform-support/x86_64-unknown-linux-none.md)
     - [x86_64-unknown-none](platform-support/x86_64-unknown-none.md)
-    - [x86_64h-apple-darwin](platform-support/x86_64h-apple-darwin.md)
 - [Targets](targets/index.md)
     - [Built-in Targets](targets/built-in.md)
     - [Custom Targets](targets/custom.md)
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index 8adc410455e..77859956c95 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -36,7 +36,7 @@ target | notes
 `i686-pc-windows-gnu` | 32-bit MinGW (Windows 10+) [^x86_32-floats-return-ABI]
 `i686-pc-windows-msvc` | 32-bit MSVC (Windows 10+) [^x86_32-floats-return-ABI]
 `i686-unknown-linux-gnu` | 32-bit Linux (kernel 3.2+, glibc 2.17+) [^x86_32-floats-return-ABI]
-`x86_64-apple-darwin` | 64-bit macOS (10.12+, Sierra+)
+[`x86_64-apple-darwin`](platform-support/apple-darwin.md) | 64-bit macOS (10.12+, Sierra+)
 `x86_64-pc-windows-gnu` | 64-bit MinGW (Windows 10+)
 `x86_64-pc-windows-msvc` | 64-bit MSVC (Windows 10+)
 `x86_64-unknown-linux-gnu` | 64-bit Linux (kernel 3.2+, glibc 2.17+)
@@ -86,7 +86,7 @@ so Rustup may install the documentation for a similar tier 1 target instead.
 
 target | notes
 -------|-------
-`aarch64-apple-darwin` | ARM64 macOS (11.0+, Big Sur+)
+[`aarch64-apple-darwin`](platform-support/apple-darwin.md) | ARM64 macOS (11.0+, Big Sur+)
 `aarch64-pc-windows-msvc` | ARM64 Windows MSVC
 `aarch64-unknown-linux-musl` | ARM64 Linux with musl 1.2.3
 `arm-unknown-linux-gnueabi` | Armv6 Linux (kernel 3.2, glibc 2.17)
@@ -133,8 +133,8 @@ so Rustup may install the documentation for a similar tier 1 target instead.
 
 target | std | notes
 -------|:---:|-------
-`aarch64-apple-ios` | ✓ | ARM64 iOS
-[`aarch64-apple-ios-sim`](platform-support/aarch64-apple-ios-sim.md) | ✓ | Apple iOS Simulator on ARM64
+[`aarch64-apple-ios`](platform-support/apple-ios.md) | ✓ | ARM64 iOS
+[`aarch64-apple-ios-sim`](platform-support/apple-ios.md) | ✓ | Apple iOS Simulator on ARM64
 `aarch64-fuchsia` | ✓ | Alias for `aarch64-unknown-fuchsia`
 [`aarch64-unknown-fuchsia`](platform-support/fuchsia.md) | ✓ | ARM64 Fuchsia
 [`aarch64-linux-android`](platform-support/android.md) | ✓ | ARM64 Android
@@ -192,7 +192,7 @@ target | std | notes
 `wasm32-wasi` | ✓ | WebAssembly with WASI (undergoing a [rename to `wasm32-wasip1`][wasi-rename])
 [`wasm32-wasip1`](platform-support/wasm32-wasip1.md) | ✓ | WebAssembly with WASI
 [`wasm32-wasip1-threads`](platform-support/wasm32-wasip1-threads.md) | ✓ |  | WebAssembly with WASI Preview 1 and threads
-`x86_64-apple-ios` | ✓ | 64-bit x86 iOS
+[`x86_64-apple-ios`](platform-support/apple-ios.md) | ✓ | 64-bit x86 iOS
 [`x86_64-fortanix-unknown-sgx`](platform-support/x86_64-fortanix-unknown-sgx.md) | ✓ | [Fortanix ABI] for 64-bit Intel SGX
 `x86_64-fuchsia` | ✓ | Alias for `x86_64-unknown-fuchsia`
 [`x86_64-unknown-fuchsia`](platform-support/fuchsia.md) | ✓ | 64-bit x86 Fuchsia
@@ -241,9 +241,9 @@ target | std | host | notes
 [`arm64e-apple-ios`](platform-support/arm64e-apple-ios.md) | ✓ | | ARM64e Apple iOS
 [`arm64e-apple-darwin`](platform-support/arm64e-apple-darwin.md)  | ✓ | ✓ | ARM64e Apple Darwin
 [`arm64ec-pc-windows-msvc`](platform-support/arm64ec-pc-windows-msvc.md) | ? | | Arm64EC Windows MSVC
-`aarch64-apple-ios-macabi` | ? |  | Apple Catalyst on ARM64
-[`aarch64-apple-tvos`](platform-support/apple-tvos.md) | ? |  | ARM64 tvOS
-[`aarch64-apple-tvos-sim`](platform-support/apple-tvos.md) | ? |  | ARM64 tvOS Simulator
+[`aarch64-apple-ios-macabi`](platform-support/apple-ios-macabi.md) | ✓ |  | Apple Catalyst on ARM64
+[`aarch64-apple-tvos`](platform-support/apple-tvos.md) | ✓ |  | ARM64 tvOS
+[`aarch64-apple-tvos-sim`](platform-support/apple-tvos.md) | ✓ |  | ARM64 tvOS Simulator
 [`aarch64-apple-watchos`](platform-support/apple-watchos.md) | ✓ |  | ARM64 Apple WatchOS
 [`aarch64-apple-watchos-sim`](platform-support/apple-watchos.md) | ✓ |  | ARM64 Apple WatchOS Simulator
 [`aarch64-apple-visionos`](platform-support/apple-visionos.md) | ✓ |  | ARM64 Apple visionOS
@@ -283,7 +283,7 @@ target | std | host | notes
 [`armv7a-kmc-solid_asp3-eabihf`](platform-support/kmc-solid.md) | ✓ |  | ARM SOLID with TOPPERS/ASP3, hardfloat
 [`armv7a-none-eabihf`](platform-support/arm-none-eabi.md) | * |  | Bare Armv7-A, hardfloat
 [`armv7k-apple-watchos`](platform-support/apple-watchos.md) | ✓ |  | Armv7-A Apple WatchOS
-`armv7s-apple-ios` | ✓ |  | Armv7-A Apple-A6 Apple iOS
+[`armv7s-apple-ios`](platform-support/apple-ios.md) | ✓ |  | Armv7-A Apple-A6 Apple iOS
 [`armv8r-none-eabihf`](platform-support/armv8r-none-eabihf.md) | * |  | Bare Armv8-R, hardfloat
 `avr-unknown-gnu-atmega328` | * |  | AVR. Requires `-Z build-std=core`
 `bpfeb-unknown-none` | * |  | BPF (big endian)
@@ -292,10 +292,10 @@ target | std | host | notes
 `csky-unknown-linux-gnuabiv2hf` | ✓ |  | C-SKY abiv2 Linux, hardfloat (little endian)
 [`hexagon-unknown-none-elf`](platform-support/hexagon-unknown-none-elf.md)| * | | Bare Hexagon (v60+, HVX)
 [`hexagon-unknown-linux-musl`](platform-support/hexagon-unknown-linux-musl.md) | ✓ | | Hexagon Linux with musl 1.2.3
-`i386-apple-ios` | ✓ |  | 32-bit x86 iOS [^x86_32-floats-return-ABI]
+[`i386-apple-ios`](platform-support/apple-ios.md) | ✓ |  | 32-bit x86 iOS [^x86_32-floats-return-ABI]
 [`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS  [^x86_32-floats-return-ABI]
 [`i586-unknown-netbsd`](platform-support/netbsd.md) | ✓ |  | 32-bit x86, restricted to Pentium
-`i686-apple-darwin` | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+) [^x86_32-floats-return-ABI]
+[`i686-apple-darwin`](platform-support/apple-darwin.md) | ✓ | ✓ | 32-bit macOS (10.12+, Sierra+) [^x86_32-floats-return-ABI]
 `i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku [^x86_32-floats-return-ABI]
 [`i686-unknown-hurd-gnu`](platform-support/hurd.md) | ✓ | ✓ | 32-bit GNU/Hurd [^x86_32-floats-return-ABI]
 [`i686-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | NetBSD/i386 with SSE2 [^x86_32-floats-return-ABI]
@@ -367,8 +367,8 @@ target | std | host | notes
 `thumbv7neon-unknown-linux-musleabihf` | ? |  | Thumb2-mode Armv7-A Linux with NEON, musl 1.2.3
 [`wasm32-wasip2`](platform-support/wasm32-wasip2.md) | ✓ |  | WebAssembly
 [`wasm64-unknown-unknown`](platform-support/wasm64-unknown-unknown.md) | ? |  | WebAssembly
-`x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst on x86_64
-[`x86_64-apple-tvos`](platform-support/apple-tvos.md) | ? |  | x86 64-bit tvOS
+[`x86_64-apple-ios-macabi`](platform-support/apple-ios-macabi.md) | ✓ |  | Apple Catalyst on x86_64
+[`x86_64-apple-tvos`](platform-support/apple-tvos.md) | ✓ |  | x86 64-bit tvOS
 [`x86_64-apple-watchos-sim`](platform-support/apple-watchos.md) | ✓ |  | x86 64-bit Apple WatchOS simulator
 [`x86_64-pc-nto-qnx710`](platform-support/nto-qnx.md) | ✓ |  | x86 64-bit QNX Neutrino 7.1 RTOS |
 [`x86_64-unikraft-linux-musl`](platform-support/unikraft-linux-musl.md) | ✓ |   | 64-bit Unikraft with musl 1.2.3
diff --git a/src/doc/rustc/src/platform-support/aarch64-apple-ios-sim.md b/src/doc/rustc/src/platform-support/aarch64-apple-ios-sim.md
deleted file mode 100644
index 3f29e2c5e1f..00000000000
--- a/src/doc/rustc/src/platform-support/aarch64-apple-ios-sim.md
+++ /dev/null
@@ -1,55 +0,0 @@
-# aarch64-apple-ios-sim
-
-**Tier: 2**
-
-Apple iOS Simulator on ARM64.
-
-## Designated Developers
-
-* [@badboy](https://github.com/badboy)
-* [@deg4uss3r](https://github.com/deg4uss3r)
-
-## Requirements
-
-This target is cross-compiled.
-To build this target Xcode 12 or higher on macOS is required.
-
-## Building
-
-The target can be built by enabling it for a `rustc` build:
-
-```toml
-[build]
-build-stage = 1
-target = ["aarch64-apple-ios-sim"]
-```
-
-## Cross-compilation
-
-This target can be cross-compiled from `x86_64` or `aarch64` macOS hosts.
-
-Other hosts are not supported for cross-compilation, but might work when also providing the required Xcode SDK.
-
-## Testing
-
-Currently there is no support to run the rustc test suite for this target.
-
-
-## Building Rust programs
-
-*Note: Building for this target requires the corresponding iOS SDK, as provided by Xcode 12+.*
-
-From Rust Nightly 1.56.0 (2021-08-03) on the artifacts are shipped pre-compiled:
-
-```text
-rustup target add aarch64-apple-ios-sim --toolchain nightly
-```
-
-Rust programs can be built for that target:
-
-```text
-rustc --target aarch64-apple-ios-sim your-code.rs
-```
-
-There is no easy way to run simple programs in the iOS simulator.
-Static library builds can be embedded into iOS applications.
diff --git a/src/doc/rustc/src/platform-support/apple-darwin.md b/src/doc/rustc/src/platform-support/apple-darwin.md
new file mode 100644
index 00000000000..0fb86949a4b
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/apple-darwin.md
@@ -0,0 +1,59 @@
+# `*-apple-darwin`
+
+Apple macOS targets.
+
+**Tier: 1**
+
+- `x86_64-apple-darwin`: macOS on 64-bit x86.
+
+**Tier: 2 (with Host Tools)**
+
+- `aarch64-apple-darwin`: macOS on ARM64 (M1-family or later Apple Silicon CPUs).
+
+## Target maintainers
+
+- [@thomcc](https://github.com/thomcc)
+- [@madsmtm](https://github.com/madsmtm)
+
+## Requirements
+
+### OS version
+
+The minimum supported version is macOS 10.12 Sierra on x86, and macOS 11.0 Big
+Sur on ARM64.
+
+This version can be raised per-binary by changing the [deployment target],
+which might yield more performance optimizations. `rustc` respects the common
+environment variables used by Xcode to do so, in this case
+`MACOSX_DEPLOYMENT_TARGET`.
+
+The current default deployment target for `rustc` can be retrieved with
+[`rustc --print=deployment-target`][rustc-print].
+
+[deployment target]: https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/cross_development/Configuring/configuring.html
+[rustc-print]: ../command-line-arguments.md#option-print
+
+### Binary format
+
+The default binary format is Mach-O, the executable format used on Apple's
+platforms.
+
+## Building
+
+These targets are distributed through `rustup`, and otherwise require no
+special configuration.
+
+## Testing
+
+There are no special requirements for testing and running this target.
+
+x86 binaries can be run on Apple Silicon by using Rosetta.
+
+## Cross-compilation toolchains and C code
+
+Cross-compilation of these targets are supported using Clang, but may require
+Xcode or the macOS SDK (`MacOSX.sdk`) to be available to compile C code and
+to link.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
diff --git a/src/doc/rustc/src/platform-support/apple-ios-macabi.md b/src/doc/rustc/src/platform-support/apple-ios-macabi.md
new file mode 100644
index 00000000000..278ee94b6d4
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/apple-ios-macabi.md
@@ -0,0 +1,58 @@
+# `*-apple-ios-macabi`
+
+Apple Mac Catalyst targets.
+
+**Tier: 3**
+
+- `aarch64-apple-ios-macabi`: Mac Catalyst on ARM64.
+- `x86_64-apple-ios-macabi`: Mac Catalyst on 64-bit x86.
+
+## Target maintainers
+
+- [@madsmtm](https://github.com/madsmtm)
+
+## Requirements
+
+These targets are cross-compiled, and require the corresponding macOS SDK
+(`MacOSX.sdk`) which contain `./System/iOSSupport` headers to allow linking to
+iOS-specific headers, as provided by Xcode 11 or higher.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
+
+### OS version
+
+The minimum supported version is iOS 13.1.
+
+This can be raised per-binary by changing the deployment target. `rustc`
+respects the common environment variables used by Xcode to do so, in this
+case `IPHONEOS_DEPLOYMENT_TARGET`.
+
+## Building the target
+
+The targets can be built by enabling them for a `rustc` build in
+`config.toml`, by adding, for example:
+
+```toml
+[build]
+target = ["aarch64-apple-ios-macabi", "x86_64-apple-ios-macabi"]
+```
+
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
+
+## Building Rust programs
+
+Rust programs can be built for these targets by specifying `--target`, if
+`rustc` has been built with support for them. For example:
+
+```console
+$ rustc --target aarch64-apple-ios-macabi your-code.rs
+```
+
+## Testing
+
+Mac Catalyst binaries can be run directly on macOS 10.15 Catalina or newer.
+
+x86 binaries can be run on Apple Silicon by using Rosetta.
+
+Note that using certain UIKit functionality requires the binary to be bundled.
diff --git a/src/doc/rustc/src/platform-support/apple-ios.md b/src/doc/rustc/src/platform-support/apple-ios.md
new file mode 100644
index 00000000000..5045f810400
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/apple-ios.md
@@ -0,0 +1,74 @@
+# `*-apple-ios`
+
+Apple iOS / iPadOS targets.
+
+**Tier: 2 (without Host Tools)**
+
+- `aarch64-apple-ios`: Apple iOS on ARM64.
+- `aarch64-apple-ios-sim`: Apple iOS Simulator on ARM64.
+- `x86_64-apple-ios`: Apple iOS Simulator on 64-bit x86.
+
+**Tier: 3**
+
+- `armv7s-apple-ios`: Apple iOS on Armv7-A.
+- `i386-apple-ios`: Apple iOS Simulator on 32-bit x86.
+
+## Target maintainers
+
+- [@badboy](https://github.com/badboy)
+- [@deg4uss3r](https://github.com/deg4uss3r)
+- [@madsmtm](https://github.com/madsmtm)
+
+## Requirements
+
+These targets are cross-compiled, and require the corresponding iOS SDK
+(`iPhoneOS.sdk` or `iPhoneSimulator.sdk`), as provided by Xcode. To build the
+ARM64 targets, Xcode 12 or higher is required.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
+
+### OS version
+
+The minimum supported version is iOS 10.0.
+
+This can be raised per-binary by changing the deployment target. `rustc`
+respects the common environment variables used by Xcode to do so, in this
+case `IPHONEOS_DEPLOYMENT_TARGET`.
+
+## Building the target
+
+The tier 2 targets are distributed through `rustup`, and can be installed
+using one of:
+```console
+$ rustup target add aarch64-apple-ios
+$ rustup target add aarch64-apple-ios-sim
+$ rustup target add x86_64-apple-ios
+```
+
+The tier 3 targets can be built by enabling them for a `rustc` build in
+`config.toml`, by adding, for example:
+
+```toml
+[build]
+target = ["armv7s-apple-ios", "i386-apple-ios"]
+```
+
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
+
+## Building Rust programs
+
+Rust programs can be built for these targets by specifying `--target`, if
+`rustc` has been built with support for them. For example:
+
+```console
+$ rustc --target aarch64-apple-ios your-code.rs
+```
+
+## Testing
+
+There is no support for running the Rust or standard library testsuite at the
+moment. Testing has mostly been done manually with builds of static libraries
+embedded into applications called from Xcode or a simulator.
+
+It hopefully will be possible to improve this in the future.
diff --git a/src/doc/rustc/src/platform-support/apple-tvos.md b/src/doc/rustc/src/platform-support/apple-tvos.md
index e7ea109df1b..7a3b601579a 100644
--- a/src/doc/rustc/src/platform-support/apple-tvos.md
+++ b/src/doc/rustc/src/platform-support/apple-tvos.md
@@ -1,40 +1,44 @@
 # `*-apple-tvos`
-- aarch64-apple-tvos
-- x86_64-apple-tvos
+
+Apple tvOS targets.
 
 **Tier: 3**
 
-Apple tvOS targets:
-- Apple tvOS on aarch64
-- Apple tvOS Simulator on x86_64
+- `aarch64-apple-tvos`: Apple tvOS on ARM64.
+- `aarch64-apple-tvos-sim`: Apple tvOS Simulator on ARM64.
+- `x86_64-apple-tvos`: Apple tvOS Simulator on x86_64.
 
 ## Target maintainers
 
-* [@thomcc](https://github.com/thomcc)
+- [@thomcc](https://github.com/thomcc)
+- [@madsmtm](https://github.com/madsmtm)
 
 ## Requirements
 
-These targets are cross-compiled. You will need appropriate versions of Xcode
-and the SDKs for tvOS (`AppleTVOS.sdk`) and/or the tvOS Simulator
-(`AppleTVSimulator.sdk`) to build a toolchain and target these platforms.
+These targets are cross-compiled, and require the corresponding tvOS SDK
+(`AppleTVOS.sdk` or `AppleTVSimulator.sdk`), as provided by Xcode. To build the
+ARM64 targets, Xcode 12 or higher is required.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
 
-The targets support most (see below) of the standard library including the
-allocator to the best of my knowledge, however they are very new, not yet
-well-tested, and it is possible that there are various bugs.
+### OS version
 
-In theory we support back to tvOS version 7.0, although the actual minimum
-version you can target may be newer than this, for example due to the versions
-of Xcode and your SDKs.
+The minimum supported version is tvOS 10.0, although the actual minimum version
+you can target may be newer than this, for example due to the versions of Xcode
+and your SDKs.
 
-As with the other Apple targets, `rustc` respects the common environment
-variables used by Xcode to configure this, in this case
-`TVOS_DEPLOYMENT_TARGET`.
+The version can be raised per-binary by changing the deployment target. `rustc`
+respects the common environment variables used by Xcode to do so, in this
+case `TVOS_DEPLOYMENT_TARGET`.
 
-#### Incompletely supported library functionality
+### Incompletely supported library functionality
 
-As mentioned, "most" of the standard library is supported, which means that some portions
-are known to be unsupported. The following APIs are currently known to have
-missing or incomplete support:
+The targets support most of the standard library including the allocator to the
+best of my knowledge, however they are very new, not yet well-tested, and it is
+possible that there are various bugs.
+
+The following APIs are currently known to have missing or incomplete support:
 
 - `std::process::Command`'s API will return an error if it is configured in a
   manner which cannot be performed using `posix_spawn` -- this is because the
@@ -47,41 +51,30 @@ missing or incomplete support:
 
 ## Building the target
 
-The targets can be built by enabling them for a `rustc` build in `config.toml`, by adding, for example:
+The targets can be built by enabling them for a `rustc` build in
+`config.toml`, by adding, for example:
 
 ```toml
 [build]
 build-stage = 1
-target = ["aarch64-apple-tvos", "x86_64-apple-tvos", "aarch64-apple-tvos-sim"]
+target = ["aarch64-apple-tvos", "aarch64-apple-tvos-sim"]
 ```
 
-It's possible that cargo under `-Zbuild-std` may also be used to target them.
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
 
 ## Building Rust programs
 
-*Note: Building for this target requires the corresponding TVOS SDK, as provided by Xcode.*
-
-Rust programs can be built for these targets
+Rust programs can be built for these targets by specifying `--target`, if
+`rustc` has been built with support for them. For example:
 
-```text
+```console
 $ rustc --target aarch64-apple-tvos your-code.rs
-...
-$ rustc --target x86_64-apple-tvos your-code.rs
-...
-$ rustc --target aarch64-apple-tvos-sim your-code.rs
 ```
 
 ## Testing
 
-There is no support for running the Rust or standard library testsuite on tvOS
-or the simulators at the moment. Testing has mostly been done manually with
-builds of static libraries called from Xcode or a simulator.
+There is no support for running the Rust or standard library testsuite at the
+moment. Testing has mostly been done manually with builds of static libraries
+embedded into applications called from Xcode or a simulator.
 
 It hopefully will be possible to improve this in the future.
-
-## Cross-compilation toolchains and C code
-
-This target can be cross-compiled from x86_64 or aarch64 macOS hosts.
-
-Other hosts are not supported for cross-compilation, but might work when also
-providing the required Xcode SDK.
diff --git a/src/doc/rustc/src/platform-support/apple-visionos.md b/src/doc/rustc/src/platform-support/apple-visionos.md
index 9874126e42f..56224d7e20d 100644
--- a/src/doc/rustc/src/platform-support/apple-visionos.md
+++ b/src/doc/rustc/src/platform-support/apple-visionos.md
@@ -1,53 +1,67 @@
-# aarch64-apple-visionos\*
+# `*-apple-visionos`
 
--   aarch64-apple-visionos
--   aarch64-apple-visionos-sim
+Apple visionOS / xrOS targets.
 
 **Tier: 3**
 
-Apple visionOS targets:
-
--   Apple visionOS on arm64
--   Apple visionOS Simulator on arm64
+- `aarch64-apple-visionos`: Apple visionOS on arm64.
+- `aarch64-apple-visionos-sim`: Apple visionOS Simulator on arm64.
 
 ## Target maintainers
 
--   [@agg23](https://github.com/agg23)
--   [@madsmtm](https://github.com/madsmtm)
+- [@agg23](https://github.com/agg23)
+- [@madsmtm](https://github.com/madsmtm)
 
 ## Requirements
 
-These targets are cross-compiled.
-To build these targets Xcode 15 or higher on macOS is required, along with LLVM 18.
+These targets are cross-compiled, and require the corresponding visionOS SDK
+(`XROS.sdk` or `XRSimulator.sdk`), as provided by Xcode 15 or newer.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
+
+### OS version
+
+The minimum supported version is visionOS 1.0.
+
+This can be raised per-binary by changing the deployment target. `rustc`
+respects the common environment variables used by Xcode to do so, in this
+case `XROS_DEPLOYMENT_TARGET`.
 
 ## Building the target
 
-The targets can be built by enabling them for a `rustc` build, for example:
+The targets can be built by enabling them for a `rustc` build in
+`config.toml`, by adding, for example:
 
 ```toml
 [build]
-build-stage = 1
-target = ["aarch64-apple-visionos-sim"]
+target = ["aarch64-apple-visionos", "aarch64-apple-visionos-sim"]
 ```
 
-## Building Rust programs
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
 
-_Note: Building for this target requires the corresponding visionOS SDK, as provided by Xcode 15+._
+Note: Currently, a newer version of `libc` and `cc` may be required, this will
+be fixed in [#124560](https://github.com/rust-lang/rust/pull/124560).
+
+## Building Rust programs
 
-Rust programs can be built for these targets, if `rustc` has been built with support for them, for example:
+Rust programs can be built for these targets by specifying `--target`, if
+`rustc` has been built with support for them. For example:
 
-```text
-rustc --target aarch64-apple-visionos-sim your-code.rs
+```console
+$ rustc --target aarch64-apple-visionos-sim your-code.rs
 ```
 
 ## Testing
 
-There is no support for running the Rust testsuite on visionOS or the simulators.
+There is no support for running the Rust or standard library testsuite at the
+moment. Testing has mostly been done manually with builds of static libraries
+embedded into applications called from Xcode or a simulator.
 
-There is no easy way to run simple programs on visionOS or the visionOS simulators. Static library builds can be embedded into visionOS applications.
+It hopefully will be possible to improve this in the future.
 
 ## Cross-compilation toolchains and C code
 
-This target can be cross-compiled from x86_64 or aarch64 macOS hosts.
+The Clang target is suffixed with `-xros` for historical reasons.
 
-Other hosts are not supported for cross-compilation, but might work when also providing the required Xcode SDK.
+LLVM 18 or newer is required to build this target.
diff --git a/src/doc/rustc/src/platform-support/apple-watchos.md b/src/doc/rustc/src/platform-support/apple-watchos.md
index 7be2467352c..8ba35f70b85 100644
--- a/src/doc/rustc/src/platform-support/apple-watchos.md
+++ b/src/doc/rustc/src/platform-support/apple-watchos.md
@@ -1,58 +1,65 @@
-# *-apple-watchos
-- arm64_32-apple-watchos
-- armv7k-apple-watchos
-- aarch64-apple-watchos
-- aarch64-apple-watchos-sim
-- x86_64-apple-watchos-sim
+# `*-apple-watchos`
+
+Apple watchOS targets.
 
 **Tier: 3**
 
-Apple WatchOS targets:
-- Apple WatchOS on Arm 64_32
-- Apple WatchOS on Arm v7k
-- Apple WatchOS on Arm 64
-- Apple WatchOS Simulator on arm64
-- Apple WatchOS Simulator on x86_64
+- `aarch64-apple-watchos`: Apple WatchOS on ARM64.
+- `aarch64-apple-watchos-sim`: Apple WatchOS Simulator on ARM64.
+- `x86_64-apple-watchos-sim`: Apple WatchOS Simulator on 64-bit x86.
+- `arm64_32-apple-watchos`: Apple WatchOS on Arm 64_32.
+- `armv7k-apple-watchos`: Apple WatchOS on Armv7k.
 
 ## Target maintainers
 
-* [@deg4uss3r](https://github.com/deg4uss3r)
-* [@vladimir-ea](https://github.com/vladimir-ea)
-* [@leohowell](https://github.com/leohowell)
+- [@deg4uss3r](https://github.com/deg4uss3r)
+- [@vladimir-ea](https://github.com/vladimir-ea)
+- [@leohowell](https://github.com/leohowell)
+- [@madsmtm](https://github.com/madsmtm)
 
 ## Requirements
 
-These targets are cross-compiled.
-To build these targets Xcode 12 or higher on macOS is required.
+These targets are cross-compiled, and require the corresponding watchOS SDK
+(`WatchOS.sdk` or `WatchSimulator.sdk`), as provided by Xcode. To build the
+ARM64 targets, Xcode 12 or higher is required.
+
+The path to the SDK can be passed to `rustc` using the common `SDKROOT`
+environment variable.
+
+### OS version
+
+The minimum supported version is watchOS 5.0.
+
+This can be raised per-binary by changing the deployment target. `rustc`
+respects the common environment variables used by Xcode to do so, in this
+case `WATCHOS_DEPLOYMENT_TARGET`.
 
 ## Building the target
 
-The targets can be built by enabling them for a `rustc` build, for example:
+The targets can be built by enabling them for a `rustc` build in
+`config.toml`, by adding, for example:
 
 ```toml
 [build]
 build-stage = 1
-target = ["aarch64-apple-watchos-sim"]
+target = ["aarch64-apple-watchos", "aarch64-apple-watchos-sim"]
 ```
 
-## Building Rust programs
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
 
-*Note: Building for this target requires the corresponding WatchOS SDK, as provided by Xcode 12+.*
+## Building Rust programs
 
-Rust programs can be built for these targets, if `rustc` has been built with support for them, for example:
+Rust programs can be built for these targets by specifying `--target`, if
+`rustc` has been built with support for them. For example:
 
-```text
-rustc --target aarch64-apple-watchos-sim your-code.rs
+```console
+$ rustc --target aarch64-apple-watchos-sim your-code.rs
 ```
 
 ## Testing
 
-There is no support for running the Rust testsuite on WatchOS or the simulators.
-
-There is no easy way to run simple programs on WatchOS or the WatchOS simulators. Static library builds can be embedded into WatchOS applications.
-
-## Cross-compilation toolchains and C code
-
-This target can be cross-compiled from x86_64 or aarch64 macOS hosts.
+There is no support for running the Rust or standard library testsuite at the
+moment. Testing has mostly been done manually with builds of static libraries
+embedded into applications called from Xcode or a simulator.
 
-Other hosts are not supported for cross-compilation, but might work when also providing the required Xcode SDK.
+It hopefully will be possible to improve this in the future.
diff --git a/src/doc/rustc/src/platform-support/arm64e-apple-darwin.md b/src/doc/rustc/src/platform-support/arm64e-apple-darwin.md
index d9b9aeae1ae..4d98b3a6098 100644
--- a/src/doc/rustc/src/platform-support/arm64e-apple-darwin.md
+++ b/src/doc/rustc/src/platform-support/arm64e-apple-darwin.md
@@ -12,6 +12,8 @@ ARM64e macOS (11.0+, Big Sur+)
 
 Target for `macOS` on late-generation `M` series Apple chips.
 
+See the docs on [`*-apple-darwin`](apple-darwin.md) for general macOS requirements.
+
 ## Building the target
 
 You can build Rust with support for the targets by adding it to the `target` list in `config.toml`:
diff --git a/src/doc/rustc/src/platform-support/arm64e-apple-ios.md b/src/doc/rustc/src/platform-support/arm64e-apple-ios.md
index 0215621be3d..3c878f7250e 100644
--- a/src/doc/rustc/src/platform-support/arm64e-apple-ios.md
+++ b/src/doc/rustc/src/platform-support/arm64e-apple-ios.md
@@ -10,8 +10,7 @@ ARM64e iOS (12.0+)
 
 ## Requirements
 
-These targets only support cross-compilation.
-The targets do support `std`.
+See the docs on [`*-apple-ios`](apple-ios.md) for general iOS requirements.
 
 ## Building the target
 
diff --git a/src/doc/rustc/src/platform-support/i686-apple-darwin.md b/src/doc/rustc/src/platform-support/i686-apple-darwin.md
new file mode 100644
index 00000000000..d69fa97ce63
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/i686-apple-darwin.md
@@ -0,0 +1,41 @@
+# `i686-apple-darwin`
+
+Apple macOS on 32-bit x86.
+
+## Target maintainers
+
+- [@thomcc](https://github.com/thomcc)
+- [@madsmtm](https://github.com/madsmtm)
+
+## Requirements
+
+See the docs on [`*-apple-darwin`](apple-darwin.md) for general macOS requirements.
+
+## Building the target
+
+You'll need the macOS 10.13 SDK shipped with Xcode 9. The location of the SDK
+can be passed to `rustc` using the common `SDKROOT` environment variable.
+
+Once you have that, you can build Rust with support for the target by adding
+it to the `target` list in `config.toml`:
+
+```toml
+[build]
+target = ["i686-apple-darwin"]
+```
+
+Using the unstable `-Zbuild-std` with a nightly Cargo may also work.
+
+## Building Rust programs
+
+Rust [no longer] ships pre-compiled artifacts for this target. To compile for
+this target, you will either need to build Rust with the target enabled (see
+"Building the target" above), or build your own copy using `build-std` or
+similar.
+
+[no longer]: https://blog.rust-lang.org/2020/01/03/reducing-support-for-32-bit-apple-targets.html
+
+## Testing
+
+Running this target requires an Intel Macbook running macOS 10.14 or earlier,
+as later versions removed support for running 32-bit binaries.
diff --git a/src/doc/rustc/src/platform-support/x86_64h-apple-darwin.md b/src/doc/rustc/src/platform-support/x86_64h-apple-darwin.md
index 0fe9d4edaca..6c2a6a41101 100644
--- a/src/doc/rustc/src/platform-support/x86_64h-apple-darwin.md
+++ b/src/doc/rustc/src/platform-support/x86_64h-apple-darwin.md
@@ -23,9 +23,8 @@ default or user-defined allocators). This target is probably most useful when
 targeted via cross-compilation (including from `x86_64-apple-darwin`), but if
 built manually, the host tools work.
 
-It is similar to `x86_64-apple-darwin` in nearly all respects, although the
-minimum supported OS version is slightly higher (it requires 10.8 rather than
-`x86_64-apple-darwin`'s 10.7).
+It is similar to [`x86_64-apple-darwin`](apple-darwin.md) in nearly all
+respects.
 
 ## Building the target
 
diff --git a/src/tools/miri/src/intrinsics/simd.rs b/src/tools/miri/src/intrinsics/simd.rs
index 4cde364fbc4..e178187ffa6 100644
--- a/src/tools/miri/src/intrinsics/simd.rs
+++ b/src/tools/miri/src/intrinsics/simd.rs
@@ -42,6 +42,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             | "flog2"
             | "flog10"
             | "ctlz"
+            | "ctpop"
             | "cttz"
             | "bswap"
             | "bitreverse"
@@ -68,6 +69,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     "round" => Op::Round(rustc_apfloat::Round::NearestTiesToAway),
                     "trunc" => Op::Round(rustc_apfloat::Round::TowardZero),
                     "ctlz" => Op::Numeric(sym::ctlz),
+                    "ctpop" => Op::Numeric(sym::ctpop),
                     "cttz" => Op::Numeric(sym::cttz),
                     "bswap" => Op::Numeric(sym::bswap),
                     "bitreverse" => Op::Numeric(sym::bitreverse),
diff --git a/src/tools/miri/tests/pass/intrinsics/portable-simd.rs b/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
index 1fc713d48dc..248a57d6850 100644
--- a/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
+++ b/src/tools/miri/tests/pass/intrinsics/portable-simd.rs
@@ -506,6 +506,21 @@ fn simd_intrinsics() {
         assert!(!simd_reduce_all(i32x2::from_array([0, -1])));
 
         assert_eq!(
+            simd_ctlz(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([32, 1, 0, 0])
+        );
+
+        assert_eq!(
+            simd_ctpop(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([0, 31, 1, 32])
+        );
+
+        assert_eq!(
+            simd_cttz(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([32, 0, 31, 0])
+        );
+
+        assert_eq!(
             simd_select(i8x4::from_array([0, -1, -1, 0]), a, b),
             i32x4::from_array([1, 10, 10, 4])
         );
diff --git a/src/tools/tidy/src/allowed_run_make_makefiles.txt b/src/tools/tidy/src/allowed_run_make_makefiles.txt
index 9b879f33778..3f4fceccab0 100644
--- a/src/tools/tidy/src/allowed_run_make_makefiles.txt
+++ b/src/tools/tidy/src/allowed_run_make_makefiles.txt
@@ -177,7 +177,6 @@ run-make/no-alloc-shim/Makefile
 run-make/no-builtins-attribute/Makefile
 run-make/no-builtins-lto/Makefile
 run-make/no-duplicate-libs/Makefile
-run-make/no-intermediate-extras/Makefile
 run-make/obey-crate-type-flag/Makefile
 run-make/optimization-remarks-dir-pgo/Makefile
 run-make/optimization-remarks-dir/Makefile
diff --git a/tests/run-make/no-intermediate-extras/Makefile b/tests/run-make/no-intermediate-extras/Makefile
deleted file mode 100644
index 83b5cedcf2a..00000000000
--- a/tests/run-make/no-intermediate-extras/Makefile
+++ /dev/null
@@ -1,8 +0,0 @@
-# ignore-cross-compile
-# Regression test for issue #10973
-
-include ../tools.mk
-
-all:
-	$(RUSTC) --crate-type=rlib --test foo.rs
-	rm $(TMPDIR)/foo.bc && exit 1 || exit 0
diff --git a/tests/run-make/no-intermediate-extras/rmake.rs b/tests/run-make/no-intermediate-extras/rmake.rs
new file mode 100644
index 00000000000..19479e3bd5b
--- /dev/null
+++ b/tests/run-make/no-intermediate-extras/rmake.rs
@@ -0,0 +1,17 @@
+// When using the --test flag with an rlib, this used to generate
+// an unwanted .bc file, which should not exist. This test checks
+// that the bug causing the generation of this file has not returned.
+// See https://github.com/rust-lang/rust/issues/10973
+
+//@ ignore-cross-compile
+
+use run_make_support::{rustc, tmp_dir};
+use std::fs;
+
+fn main() {
+    rustc().crate_type("rlib").arg("--test").input("foo.rs").run();
+    assert!(
+        fs::remove_file(tmp_dir().join("foo.bc")).is_err(),
+        "An unwanted .bc file was created by run-make/no-intermediate-extras."
+    );
+}
diff --git a/tests/ui/simd/intrinsic/generic-arithmetic-2.rs b/tests/ui/simd/intrinsic/generic-arithmetic-2.rs
index 4ad98d56711..fc3087cbf75 100644
--- a/tests/ui/simd/intrinsic/generic-arithmetic-2.rs
+++ b/tests/ui/simd/intrinsic/generic-arithmetic-2.rs
@@ -30,6 +30,7 @@ extern "rust-intrinsic" {
     fn simd_bswap<T>(x: T) -> T;
     fn simd_bitreverse<T>(x: T) -> T;
     fn simd_ctlz<T>(x: T) -> T;
+    fn simd_ctpop<T>(x: T) -> T;
     fn simd_cttz<T>(x: T) -> T;
 }
 
@@ -77,7 +78,6 @@ fn main() {
         simd_cttz(x);
         simd_cttz(y);
 
-
         simd_add(0, 0);
         //~^ ERROR expected SIMD input type, found non-SIMD `i32`
         simd_sub(0, 0);
@@ -108,24 +108,25 @@ fn main() {
         simd_cttz(0);
         //~^ ERROR expected SIMD input type, found non-SIMD `i32`
 
-
         simd_shl(z, z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_shr(z, z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_and(z, z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_or(z, z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_xor(z, z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_bswap(z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_bitreverse(z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_ctlz(z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
+        simd_ctpop(z);
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
         simd_cttz(z);
-//~^ ERROR unsupported operation on `f32x4` with element `f32`
+        //~^ ERROR unsupported operation on `f32x4` with element `f32`
     }
 }
diff --git a/tests/ui/simd/intrinsic/generic-arithmetic-2.stderr b/tests/ui/simd/intrinsic/generic-arithmetic-2.stderr
index db26f3417c9..6f5f86d7d37 100644
--- a/tests/ui/simd/intrinsic/generic-arithmetic-2.stderr
+++ b/tests/ui/simd/intrinsic/generic-arithmetic-2.stderr
@@ -83,59 +83,65 @@ LL |         simd_cttz(0);
    |         ^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shl` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:112:9
+  --> $DIR/generic-arithmetic-2.rs:111:9
    |
 LL |         simd_shl(z, z);
    |         ^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shr` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:114:9
+  --> $DIR/generic-arithmetic-2.rs:113:9
    |
 LL |         simd_shr(z, z);
    |         ^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_and` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:116:9
+  --> $DIR/generic-arithmetic-2.rs:115:9
    |
 LL |         simd_and(z, z);
    |         ^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_or` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:118:9
+  --> $DIR/generic-arithmetic-2.rs:117:9
    |
 LL |         simd_or(z, z);
    |         ^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_xor` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:120:9
+  --> $DIR/generic-arithmetic-2.rs:119:9
    |
 LL |         simd_xor(z, z);
    |         ^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_bswap` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:122:9
+  --> $DIR/generic-arithmetic-2.rs:121:9
    |
 LL |         simd_bswap(z);
    |         ^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_bitreverse` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:124:9
+  --> $DIR/generic-arithmetic-2.rs:123:9
    |
 LL |         simd_bitreverse(z);
    |         ^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_ctlz` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:126:9
+  --> $DIR/generic-arithmetic-2.rs:125:9
    |
 LL |         simd_ctlz(z);
    |         ^^^^^^^^^^^^
 
+error[E0511]: invalid monomorphization of `simd_ctpop` intrinsic: unsupported operation on `f32x4` with element `f32`
+  --> $DIR/generic-arithmetic-2.rs:127:9
+   |
+LL |         simd_ctpop(z);
+   |         ^^^^^^^^^^^^^
+
 error[E0511]: invalid monomorphization of `simd_cttz` intrinsic: unsupported operation on `f32x4` with element `f32`
-  --> $DIR/generic-arithmetic-2.rs:128:9
+  --> $DIR/generic-arithmetic-2.rs:129:9
    |
 LL |         simd_cttz(z);
    |         ^^^^^^^^^^^^
 
-error: aborting due to 23 previous errors
+error: aborting due to 24 previous errors
 
 For more information about this error, try `rustc --explain E0511`.
diff --git a/tests/ui/simd/intrinsic/generic-arithmetic-pass.rs b/tests/ui/simd/intrinsic/generic-arithmetic-pass.rs
index 33143b1f7b5..60dfa627414 100644
--- a/tests/ui/simd/intrinsic/generic-arithmetic-pass.rs
+++ b/tests/ui/simd/intrinsic/generic-arithmetic-pass.rs
@@ -47,6 +47,7 @@ extern "rust-intrinsic" {
     fn simd_bswap<T>(x: T) -> T;
     fn simd_bitreverse<T>(x: T) -> T;
     fn simd_ctlz<T>(x: T) -> T;
+    fn simd_ctpop<T>(x: T) -> T;
     fn simd_cttz<T>(x: T) -> T;
 }
 
@@ -57,6 +58,8 @@ fn main() {
     let x2 = i32x4(2, 3, 4, 5);
     let y2 = U32::<4>([2, 3, 4, 5]);
     let z2 = f32x4(2.0, 3.0, 4.0, 5.0);
+    let x3 = i32x4(0, i32::MAX, i32::MIN, -1_i32);
+    let y3 = U32::<4>([0, i32::MAX as _, i32::MIN as _, -1_i32 as _]);
 
     unsafe {
         all_eq!(simd_add(x1, x2), i32x4(3, 5, 7, 9));
@@ -147,6 +150,13 @@ fn main() {
         all_eq!(simd_ctlz(x1), i32x4(31, 30, 30, 29));
         all_eq_!(simd_ctlz(y1), U32::<4>([31, 30, 30, 29]));
 
+        all_eq!(simd_ctpop(x1), i32x4(1, 1, 2, 1));
+        all_eq_!(simd_ctpop(y1), U32::<4>([1, 1, 2, 1]));
+        all_eq!(simd_ctpop(x2), i32x4(1, 2, 1, 2));
+        all_eq_!(simd_ctpop(y2), U32::<4>([1, 2, 1, 2]));
+        all_eq!(simd_ctpop(x3), i32x4(0, 31, 1, 32));
+        all_eq_!(simd_ctpop(y3), U32::<4>([0, 31, 1, 32]));
+
         all_eq!(simd_cttz(x1), i32x4(0, 1, 0, 2));
         all_eq_!(simd_cttz(y1), U32::<4>([0, 1, 0, 2]));
     }