Add support for the x86_64h-apple-darwin target

compiler/rustc_target/src/spec/apple_base.rs

@@ -19,6 +19,7 @@ pub enum Arch {
     I386,
     I686,
     X86_64,
+    X86_64h,
     X86_64_sim,
     X86_64_macabi,
     Arm64_macabi,
@@ -36,6 +37,7 @@ impl Arch {
             I386 => "i386",
             I686 => "i686",
             X86_64 | X86_64_sim | X86_64_macabi => "x86_64",
+            X86_64h => "x86_64h",
         }
     }
 
@@ -44,13 +46,13 @@ impl Arch {
             Armv7 | Armv7k | Armv7s => "arm",
             Arm64 | Arm64_32 | Arm64_macabi | Arm64_sim => "aarch64",
             I386 | I686 => "x86",
-            X86_64 | X86_64_sim | X86_64_macabi => "x86_64",
+            X86_64 | X86_64_sim | X86_64_macabi | X86_64h => "x86_64",
         })
     }
 
     fn target_abi(self) -> &'static str {
         match self {
-            Armv7 | Armv7k | Armv7s | Arm64 | Arm64_32 | I386 | I686 | X86_64 => "",
+            Armv7 | Armv7k | Armv7s | Arm64 | Arm64_32 | I386 | I686 | X86_64 | X86_64h => "",
             X86_64_macabi | Arm64_macabi => "macabi",
             // x86_64-apple-ios is a simulator target, even though it isn't
             // declared that way in the target like the other ones...
@@ -67,6 +69,10 @@ impl Arch {
             Arm64_32 => "apple-s4",
             I386 | I686 => "yonah",
             X86_64 | X86_64_sim => "core2",
+            // Note: `core-avx2` is slightly more advanced than `x86_64h`, see
+            // comments (and disabled features) in `x86_64h_apple_darwin` for
+            // details.
+            X86_64h => "core-avx2",
             X86_64_macabi => "core2",
             Arm64_macabi => "apple-a12",
             Arm64_sim => "apple-a12",
@@ -182,8 +188,13 @@ fn deployment_target(var_name: &str) -> Option<(u32, u32)> {
 }
 
 fn macos_default_deployment_target(arch: Arch) -> (u32, u32) {
-    // Note: Arm64_sim is not included since macOS has no simulator.
-    if matches!(arch, Arm64 | Arm64_macabi) { (11, 0) } else { (10, 7) }
+    match arch {
+        // Note: Arm64_sim is not included since macOS has no simulator.
+        Arm64 | Arm64_macabi => (11, 0),
+        // x86_64h-apple-darwin only supports macOS 10.8 and later
+        X86_64h => (10, 8),
+        _ => (10, 7),
+    }
 }
 
 fn macos_deployment_target(arch: Arch) -> (u32, u32) {
@@ -227,7 +238,7 @@ fn link_env_remove(arch: Arch, os: &'static str) -> StaticCow<[StaticCow<str>]>
         // of the linking environment that's wrong and reversed.
         match arch {
             Armv7 | Armv7k | Armv7s | Arm64 | Arm64_32 | I386 | I686 | X86_64 | X86_64_sim
-            | Arm64_sim => {
+            | X86_64h | Arm64_sim => {
                 cvs!["MACOSX_DEPLOYMENT_TARGET"]
             }
             X86_64_macabi | Arm64_macabi => cvs!["IPHONEOS_DEPLOYMENT_TARGET"],

compiler/rustc_target/src/spec/mod.rs

@@ -1110,6 +1110,7 @@ supported_targets! {
 
     ("aarch64-apple-darwin", aarch64_apple_darwin),
     ("x86_64-apple-darwin", x86_64_apple_darwin),
+    ("x86_64h-apple-darwin", x86_64h_apple_darwin),
     ("i686-apple-darwin", i686_apple_darwin),
 
     // FIXME(#106649): Remove aarch64-fuchsia in favor of aarch64-unknown-fuchsia

compiler/rustc_target/src/spec/x86_64h_apple_darwin.rs

@@ -0,0 +1,44 @@
+use super::apple_base::{macos_llvm_target, opts, Arch};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, SanitizerSet};
+use crate::spec::{StackProbeType, Target, TargetOptions};
+
+pub fn target() -> Target {
+    let arch = Arch::X86_64h;
+    let mut base = opts("macos", arch);
+    base.max_atomic_width = Some(128);
+    base.frame_pointer = FramePointer::Always;
+    base.add_pre_link_args(LinkerFlavor::Darwin(Cc::Yes, Lld::No), &["-m64"]);
+    base.stack_probes = StackProbeType::X86;
+    base.supported_sanitizers =
+        SanitizerSet::ADDRESS | SanitizerSet::CFI | SanitizerSet::LEAK | SanitizerSet::THREAD;
+
+    // x86_64h is core2-avx without a few of the features which would otherwise
+    // be guaranteed, so we need to disable those. This imitates clang's logic:
+    // - https://github.com/llvm/llvm-project/blob/bd1f7c417/clang/lib/Driver/ToolChains/Arch/X86.cpp#L77-L78
+    // - https://github.com/llvm/llvm-project/blob/bd1f7c417/clang/lib/Driver/ToolChains/Arch/X86.cpp#L133-L141
+    //
+    // FIXME: Sadly, turning these off here disables them in such a way that they
+    // aren't re-enabled by `-Ctarget-cpu=native` (on a machine that has them).
+    // It would be nice if this were not the case, but fixing it seems tricky
+    // (and given that the main use-case for this target is for use in universal
+    // binaries, probably not that important).
+    base.features = "-rdrnd,-aes,-pclmul,-rtm,-fsgsbase".into();
+    // Double-check that the `cpu` is what we expect (if it's not the list above
+    // may need updating).
+    assert_eq!(
+        base.cpu, "core-avx2",
+        "you need to adjust the feature list in x86_64h-apple-darwin if you change this",
+    );
+
+    Target {
+        // Clang automatically chooses a more specific target based on
+        // MACOSX_DEPLOYMENT_TARGET. To enable cross-language LTO to work
+        // correctly, we do too.
+        llvm_target: macos_llvm_target(arch).into(),
+        pointer_width: 64,
+        data_layout: "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+            .into(),
+        arch: arch.target_arch(),
+        options: TargetOptions { mcount: "\u{1}mcount".into(), ..base },
+    }
+}