added aarch64_apple_ios_sim as a rustc target

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2187,6 +2187,7 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
         ("x86_64", "tvos") => "appletvsimulator",
         ("arm", "ios") => "iphoneos",
         ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
+        ("aarch64", "ios") if llvm_target.contains("sim") => "iphonesimulator",
         ("aarch64", "ios") => "iphoneos",
         ("x86", "ios") => "iphonesimulator",
         ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",

compiler/rustc_target/src/spec/aarch64_apple_ios_sim.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_sim);
+    Target {
+        llvm_target: "arm64-apple-ios-simulator".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-ios14.0-simulator\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

@@ -11,6 +11,7 @@ pub enum Arch {
     X86_64,
     X86_64_macabi,
     Arm64_macabi,
+    Arm64_sim,
 }
 
 fn target_cpu(arch: Arch) -> String {
@@ -22,13 +23,16 @@ fn target_cpu(arch: Arch) -> String {
         X86_64 => "core2",
         X86_64_macabi => "core2",
         Arm64_macabi => "apple-a12",
+        Arm64_sim => "apple-a12",
     }
     .to_string()
 }
 
 fn link_env_remove(arch: Arch) -> Vec<String> {
     match arch {
-        Armv7 | Armv7s | Arm64 | I386 | X86_64 => vec!["MACOSX_DEPLOYMENT_TARGET".to_string()],
+        Armv7 | Armv7s | Arm64 | I386 | X86_64 | Arm64_sim => {
+            vec!["MACOSX_DEPLOYMENT_TARGET".to_string()]
+        }
         X86_64_macabi | Arm64_macabi => vec!["IPHONEOS_DEPLOYMENT_TARGET".to_string()],
     }
 }

compiler/rustc_target/src/spec/mod.rs

@@ -727,6 +727,7 @@ supported_targets! {
     ("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-ios-sim", aarch64_apple_ios_sim),
     ("aarch64-apple-tvos", aarch64_apple_tvos),
     ("x86_64-apple-tvos", x86_64_apple_tvos),
 

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

@@ -153,6 +153,7 @@ not available.
 target | std | host | notes
 -------|-----|------|-------
 `aarch64-apple-ios-macabi` | ? |  | Apple Catalyst on ARM64
+`aarch64-apple-ios-sim` | ? |  | Apple iOS Simulator on  ARM64
 `aarch64-apple-tvos` | * |  | ARM64 tvOS
 `aarch64-unknown-freebsd` | ✓ | ✓ | ARM64 FreeBSD
 `aarch64-unknown-hermit` | ? |  |