[ABISysV] Fix regression for Simulator and MacABI

[JDevlieghere]

Summary

The ABISysV ABI was refactored in r364216 to support the Windows ABI for x86_64. In particular it changed ABISysV_x86_64::CreateInstance to switch on the OS type. This breaks debugging MacABI apps as well as apps in the simulator. This adds back the necessary cases.

We have a test on Github that exercises this code path and which I'd like to upstream once the remaining MacABI parts become available in clang.

[aprantl]

lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp

233

Can you add a comment here that this is to support older compilers that don't support the -simulator environment yet?

[aprantl]

What does x86_64-apple-darwin canonicalize to? Do we need an extra case for that?

[aprantl]

lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp

231

clang-format?

lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp

 size_t ABISysV_x86_64::GetRedZoneSize() const { return 128; }
 
 // Static Functions
 
 ABISP
 ABISysV_x86_64::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch) {
   const llvm::Triple::ArchType arch_type = arch.GetTriple().getArch();
   const llvm::Triple::OSType os_type = arch.GetTriple().getOS();
+  const llvm::Triple::EnvironmentType os_env = arch.GetTriple().getEnvironment();
   if (arch_type == llvm::Triple::x86_64) {
     switch(os_type) {
-      case llvm::Triple::OSType::MacOSX:
-      case llvm::Triple::OSType::Linux:
+      case llvm::Triple::OSType::IOS:
+      case llvm::Triple::OSType::TvOS:
+      case llvm::Triple::OSType::WatchOS:
+        switch(os_env) {
+          case llvm::Triple::EnvironmentType::Simulator:
+          case llvm::Triple::EnvironmentType::UnknownEnvironment:
+          case llvm::Triple::EnvironmentType::MacABI:
+            return ABISP(new ABISysV_x86_64(process_sp));
+          default:
+            return ABISP();
+        }
       case llvm::Triple::OSType::FreeBSD:
+      case llvm::Triple::OSType::Linux:
+      case llvm::Triple::OSType::MacOSX:
       case llvm::Triple::OSType::NetBSD:
       case llvm::Triple::OSType::Solaris:
       case llvm::Triple::OSType::UnknownOS:
         return ABISP(new ABISysV_x86_64(process_sp));
-      default: 
+      default:
         return ABISP();
     }
   }
   return ABISP();
 }
 
 bool ABISysV_x86_64::PrepareTrivialCall(Thread &thread, addr_t sp,
                                         addr_t func_addr, addr_t return_addr,