Auto merge of #77484 - terhechte:support-ios-catalyst-macabi-arm64-target-triple, r=nikomatsakis

Add support for Arm64 Catalyst on ARM Macs

This is an iteration on https://github.com/rust-lang/rust/pull/63467 which was merged a while ago. In the aforementioned PR, I added support for the `X86_64-apple-ios-macabi` target triple, which is Catalyst, iOS apps running on macOS.

Very soon, Apple will launch ARM64 based Macs which will introduce `aarch64_apple_darwin.rs`, macOS apps using the Darwin ABI running on ARM. This PR adds support for Catalyst apps on ARM Macs: iOS apps compiled for the darwin ABI.

I don't have access to a Apple Developer Transition Kit (DTK), so I can't really test if the generated binaries work correctly. I'm vaguely hopeful that somebody with access to a DTK could give this a spin.

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2090,9 +2090,10 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
         ("aarch64", "tvos") => "appletvos",
         ("x86_64", "tvos") => "appletvsimulator",
         ("arm", "ios") => "iphoneos",
+        ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
         ("aarch64", "ios") => "iphoneos",
         ("x86", "ios") => "iphonesimulator",
-        ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx10.15",
+        ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
         ("x86_64", "ios") => "iphonesimulator",
         _ => {
             sess.err(&format!("unsupported arch `{}` for os `{}`", arch, os));

compiler/rustc_target/src/spec/aarch64_apple_ios_macabi.rs

@@ -0,0 +1,31 @@
+use super::apple_sdk_base::{opts, Arch};
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    let base = opts("ios", Arch::Arm64_macabi);
+    Target {
+        llvm_target: "arm64-apple-ios-macabi".to_string(),
+        pointer_width: 64,
+        data_layout: "e-m:o-i64:64-i128:128-n32:64-S128".to_string(),
+        arch: "aarch64".to_string(),
+        options: TargetOptions {
+            features: "+neon,+fp-armv8,+apple-a7".to_string(),
+            eliminate_frame_pointer: false,
+            max_atomic_width: Some(128),
+            unsupported_abis: super::arm_base::unsupported_abis(),
+            forces_embed_bitcode: true,
+            // Taken from a clang build on Xcode 11.4.1.
+            // These arguments are not actually invoked - they just have
+            // to look right to pass App Store validation.
+            bitcode_llvm_cmdline: "-triple\0\
+                arm64-apple-ios-macabi\0\
+                -emit-obj\0\
+                -disable-llvm-passes\0\
+                -target-abi\0\
+                darwinpcs\0\
+                -Os\0"
+                .to_string(),
+            ..base
+        },
+    }
+}

compiler/rustc_target/src/spec/apple_sdk_base.rs

@@ -10,6 +10,7 @@ pub enum Arch {
     I386,
     X86_64,
     X86_64_macabi,
+    Arm64_macabi,
 }
 
 fn target_cpu(arch: Arch) -> String {
@@ -20,6 +21,7 @@ fn target_cpu(arch: Arch) -> String {
         I386 => "yonah",
         X86_64 => "core2",
         X86_64_macabi => "core2",
+        Arm64_macabi => "apple-a12",
     }
     .to_string()
 }
@@ -27,7 +29,7 @@ fn target_cpu(arch: Arch) -> String {
 fn link_env_remove(arch: Arch) -> Vec<String> {
     match arch {
         Armv7 | Armv7s | Arm64 | I386 | X86_64 => vec!["MACOSX_DEPLOYMENT_TARGET".to_string()],
-        X86_64_macabi => vec!["IPHONEOS_DEPLOYMENT_TARGET".to_string()],
+        X86_64_macabi | Arm64_macabi => vec!["IPHONEOS_DEPLOYMENT_TARGET".to_string()],
     }
 }
 

compiler/rustc_target/src/spec/mod.rs

@@ -579,6 +579,7 @@ supported_targets! {
     ("armv7-apple-ios", armv7_apple_ios),
     ("armv7s-apple-ios", armv7s_apple_ios),
     ("x86_64-apple-ios-macabi", x86_64_apple_ios_macabi),
+    ("aarch64-apple-ios-macabi", aarch64_apple_ios_macabi),
     ("aarch64-apple-tvos", aarch64_apple_tvos),
     ("x86_64-apple-tvos", x86_64_apple_tvos),
 

src/doc/rustc/src/platform-support.md

@@ -152,6 +152,7 @@ not available.
 
 target | std | host | notes
 -------|-----|------|-------
+`aarch64-apple-ios-macabi` | ? |  | Apple Catalyst on ARM64
 `aarch64-apple-tvos` | * |  | ARM64 tvOS
 `aarch64-unknown-freebsd` | ✓ | ✓ | ARM64 FreeBSD
 `aarch64-unknown-hermit` | ? |  |
@@ -207,7 +208,7 @@ target | std | host | notes
 `thumbv7a-uwp-windows-msvc` | ✓ |  |
 `thumbv7neon-unknown-linux-musleabihf` | ? |  | Thumb2-mode ARMv7a Linux with NEON, MUSL
 `thumbv4t-none-eabi` | * |  | ARMv4T T32
-`x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst
+`x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst on x86_64
 `x86_64-apple-tvos` | * | | x86 64-bit tvOS
 `x86_64-linux-kernel` | * |  | Linux kernel modules
 `x86_64-pc-solaris` | ? |  |