emulated TLS before 10.7

Author: catap

src/libstd/Cargo.toml

@@ -58,6 +58,7 @@ cc = "1.0"
 
 [features]
 default = ["std_detect_file_io", "std_detect_dlsym_getauxval"]
+macos_before_10_7 = []
 
 backtrace = [
   "backtrace_rs/dbghelp",          # backtrace/symbolize on MSVC

src/libstd/build.rs

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

src/libstd/sys/unix/fast_thread_local.rs

@@ -50,6 +50,9 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern 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);
     }
@@ -64,6 +67,10 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
     }
 
     extern {
+        #[cfg(feature = "macos_before_10_7")]
+        fn __cxa_thread_atexit(dtor: unsafe extern fn(*mut u8),
+                       arg: *mut u8);
+        #[cfg(not(feature = "macos_before_10_7"))]
         fn _tlv_atexit(dtor: unsafe extern 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

@@ -2287,7 +2287,7 @@ 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

@@ -206,6 +206,7 @@ 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

@@ -737,7 +737,7 @@ 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);
   }
 
   /// @}

src/tools/legacy-bootstrap/helper.rs

@@ -0,0 +1,15 @@
+#[cfg(target_os = "macos")]
+mod macos;
+
+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),
+    }
+}