[lldb] Fix some C++ virtual method call bugs in LLDB expression evaluation by

building method override tables for CXXMethodDecls in 
DWARFASTParserClang::CompleteTypeFromDWARF.

C++ virtual method calls in LLDB expressions may fail if the override table for
the method being called is not correct as IRGen will produce references to the
wrong (or a missing) vtable entry.

This patch does not fix calls to virtual methods with covariant return types as
it mistakenly treats these as overloads, rather than overrides. This will be
addressed in a future patch.

Review: https://reviews.llvm.org/D41997

Partially fixes <rdar://problem/14205774>

llvm-svn: 323163

3 files changed, 71 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/Makefile b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/Makefile
new file mode 100644
index 00000000000..9d4f3b7f141
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/Makefile
@@ -0,0 +1,8 @@
+LEVEL = ../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules
+
+clean::
+	rm -rf $(wildcard *.o *.d *.dSYM)
diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/TestCallOverriddenMethod.py b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/TestCallOverriddenMethod.py
new file mode 100644
index 00000000000..54709e26ecb
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/TestCallOverriddenMethod.py
@@ -0,0 +1,47 @@
+"""
+Test calling an overriden method.
+
+Note:
+  This verifies that LLDB is correctly building the method overrides table.
+  If this table is not built correctly then calls to overridden methods in
+  derived classes may generate references to non-existant vtable entries,
+  as the compiler treats the overridden method as a totally new virtual
+  method definition.
+  <rdar://problem/14205774>
+
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class ExprCommandCallOverriddenMethod(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break for main.c.
+        self.line = line_number('main.cpp', '// Set breakpoint here')
+
+    def test(self):
+        """Test calls to overridden methods in derived classes."""
+        self.build()
+
+        # Set breakpoint in main and run exe
+        self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
+        lldbutil.run_break_set_by_file_and_line(
+            self, "main.cpp", self.line, num_expected_locations=-1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # Test call to method in base class (this should always work as the base
+        # class method is never an override).
+        self.expect("expr b->foo()")
+
+        # Test call to overridden method in derived class (this will fail if the
+        # overrides table is not correctly set up, as Derived::foo will be assigned
+        # a vtable entry that does not exist in the compiled program).
+        self.expect("expr d.foo()")
diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/main.cpp b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/main.cpp
new file mode 100644
index 00000000000..54ae705d297
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/expression_command/call-overridden-method/main.cpp
@@ -0,0 +1,16 @@
+class Base {
+public:
+  virtual ~Base() {}
+  virtual void foo() {}
+};
+
+class Derived : public Base {
+public:
+  virtual void foo() {}
+};
+
+int main() {
+  Derived d;
+  Base *b = &d;
+  return 0; // Set breakpoint here
+}