emulated TLS before 10.7

Author: catap

library/std/Cargo.toml

@@ -49,6 +49,7 @@ hermit-abi = { version = "0.1.17", features = ['rustc-dep-of-std'] }
 wasi = { version = "0.9.0", features = ['rustc-dep-of-std'], default-features = false }
 
 [features]
+macos_before_10_7 = []
 backtrace = [
   "gimli-symbolize",
   'addr2line/rustc-dep-of-std',

library/std/build.rs

@@ -1,6 +1,11 @@
 use std::env;
 
+#[path = "../../src/tools/legacy-bootstrap/helper.rs"]
+mod legacy_bootstrap_helper;
+
 fn main() {
+    legacy_bootstrap_helper::insert_cargo_features();
+
     println!("cargo:rerun-if-changed=build.rs");
     let target = env::var("TARGET").expect("TARGET was not set");
     if target.contains("freebsd") {

library/std/src/sys/unix/thread_local_dtor.rs

@@ -61,6 +61,9 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     #[thread_local]
     static REGISTERED: Cell<bool> = Cell::new(false);
     if !REGISTERED.get() {
+        #[cfg(feature = "macos_before_10_7")]
+        __cxa_thread_atexit(run_dtors, ptr::null_mut());
+        #[cfg(not(feature = "macos_before_10_7"))]
         _tlv_atexit(run_dtors, ptr::null_mut());
         REGISTERED.set(true);
     }
@@ -75,6 +78,9 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     }
 
     extern "C" {
+        #[cfg(feature = "macos_before_10_7")]
+        fn __cxa_thread_atexit(dtor: unsafe extern "C" fn(*mut u8), arg: *mut u8);
+        #[cfg(not(feature = "macos_before_10_7"))]
         fn _tlv_atexit(dtor: unsafe extern "C" fn(*mut u8), arg: *mut u8);
     }
 

src/llvm-project/clang/lib/Basic/Targets/OSTargets.h

@@ -92,7 +92,7 @@ class LLVM_LIBRARY_VISIBILITY DarwinTargetInfo : public OSTargetInfo<Target> {
     this->TLSSupported = false;
 
     if (Triple.isMacOSX())
-      this->TLSSupported = !Triple.isMacOSXVersionLT(10, 7);
+      this->TLSSupported = !Triple.isMacOSXVersionLT(10, 4);
     else if (Triple.isiOS()) {
       // 64-bit iOS supported it from 8 onwards, 32-bit device from 9 onwards,
       // 32-bit simulator from 10 onwards.

src/llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp

@@ -2487,7 +2487,7 @@ static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF,
   const char *Name = "__cxa_atexit";
   if (TLS) {
     const llvm::Triple &T = CGF.getTarget().getTriple();
-    Name = T.isOSDarwin() ?  "_tlv_atexit" : "__cxa_thread_atexit";
+    Name = (T.isOSDarwin() && !T.isMacOSXVersionLT(10, 7)) ?  "_tlv_atexit" : "__cxa_thread_atexit";
   }
 
   // We're assuming that the destructor function is something we can

src/llvm-project/compiler-rt/lib/builtins/CMakeLists.txt

@@ -234,6 +234,7 @@ if(APPLE)
     atomic_flag_test_and_set_explicit.c
     atomic_signal_fence.c
     atomic_thread_fence.c
+    emutls.c
   )
 endif()
 

src/llvm-project/llvm/include/llvm/ADT/Triple.h

@@ -809,7 +809,7 @@ class Triple {
 
   /// Tests whether the target uses emulated TLS as default.
   bool hasDefaultEmulatedTLS() const {
-    return isAndroid() || isOSOpenBSD() || isWindowsCygwinEnvironment();
+    return isAndroid() || isOSOpenBSD() || isWindowsCygwinEnvironment() || isMacOSXVersionLT(10, 7);
   }
 
   /// Tests whether the target uses -data-sections as default.

src/tools/legacy-bootstrap/helper.rs

@@ -0,0 +1,16 @@
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[allow(dead_code)]
+pub fn insert_cargo_features() {
+    #[cfg(target_os = "macos")]
+    macos_feature_version();
+}
+
+#[cfg(target_os = "macos")]
+fn macos_feature_version() {
+    let version = macos::version();
+    if version < 11 {
+        println!("cargo:rustc-cfg=feature=\"macos_before_10_7\"");
+    }
+}

src/tools/legacy-bootstrap/macos.rs

@@ -0,0 +1,21 @@
+use std::str;
+use std::process;
+
+pub fn version() -> u32 {
+    match process::Command::new("sw_vers").arg("-buildVersion").output() {
+        Ok(out) =>
+            match str::from_utf8(&out.stdout) {
+                Ok(version_str) =>
+                    match version_str.get(0..2) {
+                        Some(str) =>
+                            str.parse::<u32>().unwrap(),
+                        _ =>
+                            panic!("Unexpected build version string {}", version_str),
+                    },
+                Err(e) =>
+                    panic!("Can't parse output: {}", e),
+            },
+        Err(e) =>
+            panic!("Can't run sw_vers: {}", e),
+    }
+}