5 files changed, 62 insertions, 6 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 972b9bbfe1c..b93a579df15 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -2193,6 +2193,7 @@ 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",
diff --git a/compiler/rustc_target/src/spec/aarch64_apple_ios_sim.rs b/compiler/rustc_target/src/spec/aarch64_apple_ios_sim.rs
new file mode 100644
index 00000000000..e594ceec1b7
--- /dev/null
+++ b/compiler/rustc_target/src/spec/aarch64_apple_ios_sim.rs
@@ -0,0 +1,39 @@
+use super::apple_sdk_base::{opts, Arch};
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    let base = opts("ios", Arch::Arm64_sim);
+
+    // Clang automatically chooses a more specific target based on
+    // IPHONEOS_DEPLOYMENT_TARGET.
+    // This is required for the simulator target to pick the right
+    // MACH-O commands, so we do too.
+    let arch = "arm64";
+    let llvm_target = super::apple_base::ios_sim_llvm_target(arch);
+
+    Target {
+        llvm_target: llvm_target,
+        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
+        },
+    }
+}
diff --git a/compiler/rustc_target/src/spec/apple_base.rs b/compiler/rustc_target/src/spec/apple_base.rs
index 3b458962b3d..23f1357af16 100644
--- a/compiler/rustc_target/src/spec/apple_base.rs
+++ b/compiler/rustc_target/src/spec/apple_base.rs
@@ -54,14 +54,16 @@ pub fn opts(os: &str) -> TargetOptions {
     }
 }
 
-fn macos_deployment_target() -> (u32, u32) {
-    let deployment_target = env::var("MACOSX_DEPLOYMENT_TARGET").ok();
-    let version = deployment_target
+fn deployment_target(var_name: &str) -> Option<(u32, u32)> {
+    let deployment_target = env::var(var_name).ok();
+    deployment_target
         .as_ref()
         .and_then(|s| s.split_once('.'))
-        .and_then(|(a, b)| a.parse::<u32>().and_then(|a| b.parse::<u32>().map(|b| (a, b))).ok());
+        .and_then(|(a, b)| a.parse::<u32>().and_then(|a| b.parse::<u32>().map(|b| (a, b))).ok())
+}
 
-    version.unwrap_or((10, 7))
+fn macos_deployment_target() -> (u32, u32) {
+    deployment_target("MACOSX_DEPLOYMENT_TARGET").unwrap_or((10, 7))
 }
 
 pub fn macos_llvm_target(arch: &str) -> String {
@@ -84,3 +86,12 @@ pub fn macos_link_env_remove() -> Vec<String> {
     env_remove.push("IPHONEOS_DEPLOYMENT_TARGET".to_string());
     env_remove
 }
+
+fn ios_deployment_target() -> (u32, u32) {
+    deployment_target("IPHONEOS_DEPLOYMENT_TARGET").unwrap_or((7, 0))
+}
+
+pub fn ios_sim_llvm_target(arch: &str) -> String {
+    let (major, minor) = ios_deployment_target();
+    format!("{}-apple-ios{}.{}.0-simulator", arch, major, minor)
+}
diff --git a/compiler/rustc_target/src/spec/apple_sdk_base.rs b/compiler/rustc_target/src/spec/apple_sdk_base.rs
index d894f759937..538c4ca8697 100644
--- a/compiler/rustc_target/src/spec/apple_sdk_base.rs
+++ b/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()],
     }
 }
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 5b14795f545..ae803dbdb31 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/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),