the way LLDB lazily gets complete definitions for types within the debug info.
When we run across a class/struct/union definition in the DWARF, we will only
parse the full definition if we need to. This works fine for top level types
that are assigned directly to variables and arguments, but when we have a
variable with a class, lets say "A" for this example, that has a member:
"B *m_b". Initially we don't need to hunt down a definition for this class
unless we are ever asked to do something with it ("expr m_b->getDecl()" for
example). With my previous approach to lazy type completion, we would be able
to take a "A *a" and get a complete type for it, but we wouldn't be able to
then do an "a->m_b->getDecl()" unless we always expanded all types within a
class prior to handing out the type. Expanding everything is very costly and
it would be great if there were a better way.
A few months ago I worked with the llvm/clang folks to have the
ExternalASTSource class be able to complete classes if there weren't completed
yet:
class ExternalASTSource {
....
virtual void
CompleteType (clang::TagDecl *Tag);
virtual void
CompleteType (clang::ObjCInterfaceDecl *Class);
};
This was great, because we can now have the class that is producing the AST
(SymbolFileDWARF and SymbolFileDWARFDebugMap) sign up as external AST sources
and the object that creates the forward declaration types can now also
complete them anywhere within the clang type system.
This patch makes a few major changes:
- lldb_private::Module classes now own the AST context. Previously the TypeList
objects did.
- The DWARF parsers now sign up as an external AST sources so they can complete
types.
- All of the pure clang type system wrapper code we have in LLDB (ClangASTContext,
ClangASTType, and more) can now be iterating through children of any type,
and if a class/union/struct type (clang::RecordType or ObjC interface)
is found that is incomplete, we can ask the AST to get the definition.
- The SymbolFileDWARFDebugMap class now will create and use a single AST that
all child SymbolFileDWARF classes will share (much like what happens when
we have a complete linked DWARF for an executable).
We will need to modify some of the ClangUserExpression code to take more
advantage of this completion ability in the near future. Meanwhile we should
be better off now that we can be accessing any children of variables through
pointers and always be able to resolve the clang type if needed.
llvm-svn: 123613
comes from by using a virtual function to provide it from the Module's
SymbolVendor by default. This allows the DWARF parser, when being used to
parse DWARF in .o files with a parent DWARF + debug map parser, to get its
type list from the DWARF + debug map parser so when we go and find full
definitions for types (that might come from other .o files), we can use the
type list from the debug map parser. Otherwise we ended up mixing clang types
from one .o file (say a const pointer to a forward declaration "class A") with
the a full type from another .o file. This causes expression parsing, when
copying the clang types from those parsed by the DWARF parser into the
expression AST, to fail -- for good reason. Now all types are created in the
same list.
Also added host support for crash description strings that can be set before
doing a piece of work. On MacOSX, this ties in with CrashReporter support
that allows a string to be dispalyed when the app crashes and allows
LLDB.framework to print a description string in the crash log. Right now this
is hookup up the the CommandInterpreter::HandleCommand() where each command
notes that it is about to be executed, so if we crash while trying to do this
command, we should be able to see the command that caused LLDB to exit. For
all other platforms, this is a nop.
llvm-svn: 118672
