[lldb] Fix platform selection on Apple Silicon (again)

This patch is another attempt to fix platform selection on Apple
Silicon. It partially undoes D117340 which tried to fix the issue by
always instantiating a remote-ios platform for "iPhone and iPad Apps on
Apple Silicon Macs".

While the previous patch worked for attaching, it broke launching and
everything else that expects the remote platform to be connected. I made
an attempt to work around that, but quickly found out that there were
just too may places that had this assumption baked in.

This patch takes a different approach and reverts back to marking the
host platform compatible with iOS triples. This brings us back to the
original situation where platform selection was broken for remote iOS
debugging on Apple Silicon. To fix that, we now look at the process'
host architecture to differentiate between iOS binaries running remotely
and iOS binaries running locally.

I tested the following scenarios, which now all uses the desired
platform:

  - Launching an iOS binary on macOS: uses the host platform
  - Attaching to an iOS binary on macOS: uses the host platform
  - Attaching to a remote iOS binary: uses the remote-ios platform

rdar://89840215

Differential revision: https://reviews.llvm.org/D121444

(cherry picked from commit c22c7a6)

Author: JDevlieghere

lldb/lldb/test/API/functionalities/gdb_remote_client/TestPlatformMacOSX.py

@@ -0,0 +1,60 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from lldbsuite.test.gdbclientutils import *
+from lldbsuite.test.lldbgdbclient import GDBRemoteTestBase
+
+
+class TestPlatformMacOSX(GDBRemoteTestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    class MyResponder(MockGDBServerResponder):
+
+        def __init__(self, host):
+            self.host_ostype = host
+            MockGDBServerResponder.__init__(self)
+
+        def respond(self, packet):
+            if packet == "qProcessInfo":
+                return self.qProcessInfo()
+            return MockGDBServerResponder.respond(self, packet)
+
+        def qHostInfo(self):
+            return "cputype:16777223;cpusubtype:2;ostype:%s;vendor:apple;os_version:10.15.4;maccatalyst_version:13.4;endian:little;ptrsize:8;" % self.host_ostype
+
+        def qProcessInfo(self):
+            return "pid:a860;parent-pid:d2a0;real-uid:1f5;real-gid:14;effective-uid:1f5;effective-gid:14;cputype:100000c;cpusubtype:2;ptrsize:8;ostype:ios;vendor:apple;endian:little;"
+
+        def vCont(self):
+            return "vCont;"
+
+    def platform_test(self, host, expected_triple, expected_platform):
+        self.server.responder = self.MyResponder(host)
+        if self.TraceOn():
+            self.runCmd("log enable gdb-remote packets")
+            self.addTearDownHook(
+                lambda: self.runCmd("log disable gdb-remote packets"))
+
+        target = self.dbg.CreateTargetWithFileAndArch(None, None)
+        process = self.connect(target)
+
+        triple = target.GetTriple()
+        self.assertEqual(triple, expected_triple)
+
+        platform = target.GetPlatform()
+        self.assertEqual(platform.GetName(), expected_platform)
+
+    @skipIfRemote
+    def test_ios(self):
+        self.platform_test(host="ios",
+                           expected_triple="arm64e-apple-ios-",
+                           expected_platform="remote-ios")
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    @skipUnlessArch("arm64")
+    def test_macos(self):
+        self.platform_test(host="macosx",
+                           expected_triple="arm64e-apple-ios-",
+                           expected_platform="host")

lldb/lldb/unittests/Platform/PlatformMacOSXTest.cpp

@@ -0,0 +1,52 @@
+//===-- PlatformMacOSXTest.cpp ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+
+#include "Plugins/Platform/MacOSX/PlatformMacOSX.h"
+#include "TestingSupport/SubsystemRAII.h"
+#include "lldb/Host/FileSystem.h"
+#include "lldb/Host/HostInfo.h"
+#include "lldb/Target/Platform.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+class PlatformMacOSXTest : public ::testing::Test {
+  SubsystemRAII<FileSystem, HostInfo, PlatformMacOSX> subsystems;
+};
+
+static bool containsArch(const std::vector<ArchSpec> &archs,
+                         const ArchSpec &arch) {
+  return std::find_if(archs.begin(), archs.end(), [&](const ArchSpec &other) {
+           return arch.IsExactMatch(other);
+         }) != archs.end();
+}
+
+TEST_F(PlatformMacOSXTest, TestGetSupportedArchitectures) {
+  PlatformMacOSX platform;
+
+  const ArchSpec x86_macosx_arch("x86_64-apple-macosx");
+
+  EXPECT_TRUE(containsArch(platform.GetSupportedArchitectures(x86_macosx_arch),
+                           x86_macosx_arch));
+  EXPECT_TRUE(
+      containsArch(platform.GetSupportedArchitectures({}), x86_macosx_arch));
+
+#if defined(__arm__) || defined(__arm64__) || defined(__aarch64__)
+  const ArchSpec arm64_macosx_arch("arm64-apple-macosx");
+  const ArchSpec arm64_ios_arch("arm64-apple-ios");
+
+  EXPECT_TRUE(containsArch(
+      platform.GetSupportedArchitectures(arm64_macosx_arch), arm64_ios_arch));
+  EXPECT_TRUE(
+      containsArch(platform.GetSupportedArchitectures({}), arm64_ios_arch));
+  EXPECT_FALSE(containsArch(platform.GetSupportedArchitectures(arm64_ios_arch),
+                            arm64_ios_arch));
+#endif
+}

lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp

@@ -137,8 +137,6 @@ std::vector<ArchSpec>
 PlatformMacOSX::GetSupportedArchitectures(const ArchSpec &process_host_arch) {
   std::vector<ArchSpec> result;
 #if defined(__arm__) || defined(__arm64__) || defined(__aarch64__)
-  // macOS for ARM64 support both native and translated x86_64 processes
-
   // When cmdline lldb is run on iOS, watchOS, etc, it is still
   // using "PlatformMacOSX".
   llvm::Triple::OSType host_os = GetHostOSType();
@@ -152,6 +150,16 @@ PlatformMacOSX::GetSupportedArchitectures(const ArchSpec &process_host_arch) {
     result.push_back(ArchSpec("x86_64-apple-ios-macabi"));
     result.push_back(ArchSpec("arm64-apple-ios-macabi"));
     result.push_back(ArchSpec("arm64e-apple-ios-macabi"));
+
+    // On Apple Silicon, the host platform is compatible with iOS triples to
+    // support unmodified "iPhone and iPad Apps on Apple Silicon Macs". Because
+    // the binaries are identical, we must rely on the host architecture to
+    // tell them apart and mark the host platform as compatible or not.
+    if (!process_host_arch ||
+        process_host_arch.GetTriple().getOS() == llvm::Triple::MacOSX) {
+      result.push_back(ArchSpec("arm64-apple-ios"));
+      result.push_back(ArchSpec("arm64e-apple-ios"));
+    }
   }
 #else
   x86GetSupportedArchitectures(result);

lldb/test/API/functionalities/gdb_remote_client/TestPlatformMacOSX.py

@@ -0,0 +1,60 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from lldbsuite.test.gdbclientutils import *
+from lldbsuite.test.lldbgdbclient import GDBRemoteTestBase
+
+
+class TestPlatformMacOSX(GDBRemoteTestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    class MyResponder(MockGDBServerResponder):
+
+        def __init__(self, host):
+            self.host_ostype = host
+            MockGDBServerResponder.__init__(self)
+
+        def respond(self, packet):
+            if packet == "qProcessInfo":
+                return self.qProcessInfo()
+            return MockGDBServerResponder.respond(self, packet)
+
+        def qHostInfo(self):
+            return "cputype:16777223;cpusubtype:2;ostype:%s;vendor:apple;os_version:10.15.4;maccatalyst_version:13.4;endian:little;ptrsize:8;" % self.host_ostype
+
+        def qProcessInfo(self):
+            return "pid:a860;parent-pid:d2a0;real-uid:1f5;real-gid:14;effective-uid:1f5;effective-gid:14;cputype:100000c;cpusubtype:2;ptrsize:8;ostype:ios;vendor:apple;endian:little;"
+
+        def vCont(self):
+            return "vCont;"
+
+    def platform_test(self, host, expected_triple, expected_platform):
+        self.server.responder = self.MyResponder(host)
+        if self.TraceOn():
+            self.runCmd("log enable gdb-remote packets")
+            self.addTearDownHook(
+                lambda: self.runCmd("log disable gdb-remote packets"))
+
+        target = self.dbg.CreateTargetWithFileAndArch(None, None)
+        process = self.connect(target)
+
+        triple = target.GetTriple()
+        self.assertEqual(triple, expected_triple)
+
+        platform = target.GetPlatform()
+        self.assertEqual(platform.GetName(), expected_platform)
+
+    @skipIfRemote
+    def test_ios(self):
+        self.platform_test(host="ios",
+                           expected_triple="arm64e-apple-ios-",
+                           expected_platform="remote-ios")
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    @skipUnlessArch("arm64")
+    def test_macos(self):
+        self.platform_test(host="macosx",
+                           expected_triple="arm64e-apple-ios-",
+                           expected_platform="host")

lldb/unittests/Platform/CMakeLists.txt

@@ -1,6 +1,7 @@
 add_lldb_unittest(LLDBPlatformTests
   PlatformAppleSimulatorTest.cpp
   PlatformDarwinTest.cpp
+  PlatformMacOSXTest.cpp
 
   LINK_LIBS
     lldbPluginPlatformMacOSX

lldb/unittests/Platform/PlatformMacOSXTest.cpp

@@ -0,0 +1,52 @@
+//===-- PlatformMacOSXTest.cpp ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+
+#include "Plugins/Platform/MacOSX/PlatformMacOSX.h"
+#include "TestingSupport/SubsystemRAII.h"
+#include "lldb/Host/FileSystem.h"
+#include "lldb/Host/HostInfo.h"
+#include "lldb/Target/Platform.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+class PlatformMacOSXTest : public ::testing::Test {
+  SubsystemRAII<FileSystem, HostInfo, PlatformMacOSX> subsystems;
+};
+
+static bool containsArch(const std::vector<ArchSpec> &archs,
+                         const ArchSpec &arch) {
+  return std::find_if(archs.begin(), archs.end(), [&](const ArchSpec &other) {
+           return arch.IsExactMatch(other);
+         }) != archs.end();
+}
+
+TEST_F(PlatformMacOSXTest, TestGetSupportedArchitectures) {
+  PlatformMacOSX platform;
+
+  const ArchSpec x86_macosx_arch("x86_64-apple-macosx");
+
+  EXPECT_TRUE(containsArch(platform.GetSupportedArchitectures(x86_macosx_arch),
+                           x86_macosx_arch));
+  EXPECT_TRUE(
+      containsArch(platform.GetSupportedArchitectures({}), x86_macosx_arch));
+
+#if defined(__arm__) || defined(__arm64__) || defined(__aarch64__)
+  const ArchSpec arm64_macosx_arch("arm64-apple-macosx");
+  const ArchSpec arm64_ios_arch("arm64-apple-ios");
+
+  EXPECT_TRUE(containsArch(
+      platform.GetSupportedArchitectures(arm64_macosx_arch), arm64_ios_arch));
+  EXPECT_TRUE(
+      containsArch(platform.GetSupportedArchitectures({}), arm64_ios_arch));
+  EXPECT_FALSE(containsArch(platform.GetSupportedArchitectures(arm64_ios_arch),
+                            arm64_ios_arch));
+#endif
+}