[lldb] Support arm64e Objective-C signing in the expression evaluator (#187765)

When targeting arm64e, ISA pointers, class_ro_t pointers, and interface
selectors are signed in Objective-C. This PR adds support for that in
the expression evaluator.

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -731,6 +731,9 @@ static void SetPointerAuthOptionsForArm64e(LangOptions &lang_opts) {
   lang_opts.PointerAuthReturns = true;
   lang_opts.PointerAuthAuthTraps = true;
   lang_opts.PointerAuthIndirectGotos = true;
+  lang_opts.PointerAuthObjcIsa = true;
+  lang_opts.PointerAuthObjcClassROPointers = true;
+  lang_opts.PointerAuthObjcInterfaceSel = true;
 }
 
 ClangExpressionParser::ClangExpressionParser(

lldb/test/API/commands/expression/ptrauth-objc/Makefile

@@ -0,0 +1,10 @@
+OBJC_SOURCES := main.m
+
+override ARCH := arm64e
+
+# We need an arm64e stdlib.
+USE_SYSTEM_STDLIB := 1
+
+LD_EXTRAS := -framework Foundation
+
+include Makefile.rules

lldb/test/API/commands/expression/ptrauth-objc/TestPtrAuthObjectiveC.py

@@ -0,0 +1,91 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestPtrAuthObjectiveC(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    @skipUnlessArm64eSupported
+    def test_objc_message_send(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.m", False)
+        )
+
+        self.expect_expr(
+            "[obj doubleValue]",
+            result_type="int",
+            result_value="42",
+        )
+
+    @skipUnlessArm64eSupported
+    def test_objc_message_send_with_arg(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.m", False)
+        )
+
+        self.expect_expr(
+            "[obj addValue:9]",
+            result_type="int",
+            result_value="30",
+        )
+
+    @skipUnlessArm64eSupported
+    def test_objc_alloc_and_message(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.m", False)
+        )
+
+        self.expect_expr(
+            "PtrAuthTestObj *tmp = (PtrAuthTestObj *)[[PtrAuthTestObj alloc] init]; "
+            "tmp.value = 7; [tmp doubleValue]",
+            result_type="int",
+            result_value="14",
+        )
+
+    @skipUnlessArm64eSupported
+    def test_objc_derived_class(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.m", False)
+        )
+
+        self.expect_expr(
+            "[derived tripleValue]",
+            result_type="int",
+            result_value="30",
+        )
+
+        self.expect_expr(
+            "[derived doubleValue]",
+            result_type="int",
+            result_value="20",
+        )
+
+    @skipUnlessArm64eSupported
+    def test_objc_isa_check(self):
+        self.build()
+
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.m", False)
+        )
+
+        self.expect_expr(
+            "(bool)[derived isKindOfClass:[PtrAuthTestObj class]]",
+            result_type="bool",
+            result_value="true",
+        )
+
+        self.expect_expr(
+            "(bool)[obj isKindOfClass:[PtrAuthDerived class]]",
+            result_type="bool",
+            result_value="false",
+        )

lldb/test/API/commands/expression/ptrauth-objc/main.m

@@ -0,0 +1,39 @@
+#import <Foundation/Foundation.h>
+#include <stdio.h>
+
+@interface PtrAuthTestObj : NSObject
+@property(nonatomic, assign) int value;
+- (int)doubleValue;
+- (int)addValue:(int)other;
+@end
+
+@implementation PtrAuthTestObj
+- (int)doubleValue {
+  return self.value * 2;
+}
+- (int)addValue:(int)other {
+  return self.value + other;
+}
+@end
+
+@interface PtrAuthDerived : PtrAuthTestObj
+- (int)tripleValue;
+@end
+
+@implementation PtrAuthDerived
+- (int)tripleValue {
+  return self.value * 3;
+}
+@end
+
+int main(int argc, const char *argv[]) {
+  PtrAuthTestObj *obj = [[PtrAuthTestObj alloc] init];
+  obj.value = 21;
+
+  PtrAuthDerived *derived = [[PtrAuthDerived alloc] init];
+  derived.value = 10;
+
+  int result = [obj doubleValue]; // break here
+  printf("%d %d\n", result, [derived tripleValue]);
+  return 0;
+}