This fixes a use-after-free in SymbolFileCTF. Previously, we would
remove the underlying CTF type as soon as we resolved it. However, it's
possible that we're still holding onto the CTF type while we're parsing
a dependent type, like a modifier, resulting in a use-after-free. This
patch addresses the issue by delaying the removal of the CTF type until
the type is fully resolved.
I have a XNU kernel binary that reproduces the issue and confirmed that
this solves the memory issue using ASan. However I haven't been able to
craft types by hand that reproduce this issue for a test case.
rdar://156660866
Eliminate the `lldb_private::dwarf` namespace, in favor of using
`llvm::dwarf` directly. The latter is shorter, and this avoids ambiguity
in the ABI plugins that define a `dwarf` namespace inside an anonymous
namespace.
This patch pushes the error handling boundary for the GetBitSize()
methods from Runtime into the Type and CompilerType APIs. This makes it
easier to diagnose problems thanks to more meaningful error messages
being available. GetBitSize() is often the first thing LLDB asks about a
type, so this method is particularly important for a better user
experience.
rdar://145667239
This is the behavior expected by DWARF. It also requires some fixups to
algorithms which were storing the addresses of some objects (Blocks and
Variables) relative to the beginning of the function.
There are plenty of things that still don't work in this setups, but
this change is sufficient for the expression evaluator to correctly
recognize the entry point of a function in this case.
This is the beginning of a different, more fundamental approach to
handling. This PR tries to tries to minimize functional changes. It only
makes sure that we store the true set of ranges inside the function
object, so that subsequent patches can make use of it.
(this is lldb part)
Without these explicit includes, removing other headers, who implicitly
include llvm-config.h, may have non-trivial side effects. For example,
`clangd` may report even `llvm-config.h` as "no used" in case it defines
a macro, that is explicitly used with #ifdef. It is actually amplified
with different build configs which use different set of macros.
Make SymbolFileCTF::ParseFunctions resilient against not being able to
resolve the argument or return type of a function. ResolveTypeUID can
fail for a variety of reasons so we should always check its result.
The type that caused the crash was `_Bool` which we didn't recognize
as a basic type. This commit also fixes the underlying issue and adds
a test.
rdar://126943722
Fixes:
```
[3465/3822] Building CXX object tools\lldb\source\Plugins\SymbolFile\CTF\CMakeFiles\lldbPluginSymbolFileCTF.dir\SymbolFileCTF.cpp.obj
C:\git\llvm-project\lldb\source\Plugins\SymbolFile\CTF\SymbolFileCTF.cpp(606) : warning C4715: 'lldb_private::SymbolFileCTF::CreateType': not all control paths return a value
```
LLVM supports DWARF 5 linetable extension to store source files inline
in DWARF. This is particularly useful for compiler-generated source
code. This implementation tries to materialize them as temporary files
lazily, so SBAPI clients don't need to be aware of them.
rdar://110926168
This patch revives the effort to get this Phabricator patch into
upstream:
https://reviews.llvm.org/D137900
This patch was accepted before in Phabricator but I found some
-gsimple-template-names issues that are fixed in this patch.
A fixed up version of the description from the original patch starts
now.
This patch started off trying to fix Module::FindFirstType() as it
sometimes didn't work. The issue was the SymbolFile plug-ins didn't do
any filtering of the matching types they produced, and they only looked
up types using the type basename. This means if you have two types with
the same basename, your type lookup can fail when only looking up a
single type. We would ask the Module::FindFirstType to lookup "Foo::Bar"
and it would ask the symbol file to find only 1 type matching the
basename "Bar", and then we would filter out any matches that didn't
match "Foo::Bar". So if the SymbolFile found "Foo::Bar" first, then it
would work, but if it found "Baz::Bar" first, it would return only that
type and it would be filtered out.
Discovering this issue lead me to think of the patch Alex Langford did a
few months ago that was done for finding functions, where he allowed
SymbolFile objects to make sure something fully matched before parsing
the debug information into an AST type and other LLDB types. So this
patch aimed to allow type lookups to also be much more efficient.
As LLDB has been developed over the years, we added more ways to to type
lookups. These functions have lots of arguments. This patch aims to make
one API that needs to be implemented that serves all previous lookups:
- Find a single type
- Find all types
- Find types in a namespace
This patch introduces a `TypeQuery` class that contains all of the state
needed to perform the lookup which is powerful enough to perform all of
the type searches that used to be in our API. It contain a vector of
CompilerContext objects that can fully or partially specify the lookup
that needs to take place.
If you just want to lookup all types with a matching basename,
regardless of the containing context, you can specify just a single
CompilerContext entry that has a name and a CompilerContextKind mask of
CompilerContextKind::AnyType.
Or you can fully specify the exact context to use when doing lookups
like: CompilerContextKind::Namespace "std"
CompilerContextKind::Class "foo"
CompilerContextKind::Typedef "size_type"
This change expands on the clang modules code that already used a
vector<CompilerContext> items, but it modifies it to work with
expression type lookups which have contexts, or user lookups where users
query for types. The clang modules type lookup is still an option that
can be enabled on the `TypeQuery` objects.
This mirrors the most recent addition of type lookups that took a
vector<CompilerContext> that allowed lookups to happen for the
expression parser in certain places.
Prior to this we had the following APIs in Module:
```
void
Module::FindTypes(ConstString type_name, bool exact_match, size_t max_matches,
llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
TypeList &types);
void
Module::FindTypes(llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
TypeMap &types);
void Module::FindTypesInNamespace(ConstString type_name,
const CompilerDeclContext &parent_decl_ctx,
size_t max_matches, TypeList &type_list);
```
The new Module API is much simpler. It gets rid of all three above
functions and replaces them with:
```
void FindTypes(const TypeQuery &query, TypeResults &results);
```
The `TypeQuery` class contains all of the needed settings:
- The vector<CompilerContext> that allow efficient lookups in the symbol
file classes since they can look at basename matches only realize fully
matching types. Before this any basename that matched was fully realized
only to be removed later by code outside of the SymbolFile layer which
could cause many types to be realized when they didn't need to.
- If the lookup is exact or not. If not exact, then the compiler context
must match the bottom most items that match the compiler context,
otherwise it must match exactly
- If the compiler context match is for clang modules or not. Clang
modules matches include a Module compiler context kind that allows types
to be matched only from certain modules and these matches are not needed
when d oing user type lookups.
- An optional list of languages to use to limit the search to only
certain languages
The `TypeResults` object contains all state required to do the lookup
and store the results:
- The max number of matches
- The set of SymbolFile objects that have already been searched
- The matching type list for any matches that are found
The benefits of this approach are:
- Simpler API, and only one API to implement in SymbolFile classes
- Replaces the FindTypesInNamespace that used a CompilerDeclContext as a
way to limit the search, but this only worked if the TypeSystem matched
the current symbol file's type system, so you couldn't use it to lookup
a type in another module
- Fixes a serious bug in our FindFirstType functions where if we were
searching for "foo::bar", and we found a "baz::bar" first, the basename
would match and we would only fetch 1 type using the basename, only to
drop it from the matching list and returning no results
Improve memory usage by reducing the lifetime of CTF types. Once a CTF
type has been converted to a (complete) LLDB type, there's no need to
keep it in memory anymore. For most types, we can free them right after
creating the corresponding LLDB types. The only exception is record
types, which are only completed lazily.
Differential revision: https://reviews.llvm.org/D156606
Support recursive record types in CTF, for example a struct that
contains a pointer to itself:
struct S {
struct S *n;
};
We are now more lazy when creating LLDB types. When encountering a
record type (struct or union) we create a forward declaration and only
complete it when requested.
Differential revision: https://reviews.llvm.org/D156498
Fix parsing of large structs. If the size of a struct exceeds a certain
threshold, the offset is encoded using two 32-bit integers instead of
one.
Differential revision: https://reviews.llvm.org/D156490
Separate parsing CTF and creating LLDB types. This is a prerequisite to
parsing forward references and recursive types.
Differential revision: https://reviews.llvm.org/D156447
Add support for compressed CTF data. The flags in the header can
indicate whether the CTF body is compressed with zlib deflate. This
patch supports inflating the data before parsing.
Differential revision: https://reviews.llvm.org/D155221
Add support for the Compact C Type Format (CTF) in LLDB. The format
describes the layout and sizes of C types. It is most commonly consumed
by dtrace.
We generate CTF for the XNU kernel and want to be able to use this in
LLDB to debug kernels for which we don't have dSYMs (anymore). CTF is a
much more limited debug format than DWARF which allows is to be an order
of magnitude smaller: a 1GB dSYM can be converted to a handful of
megabytes of CTF. For XNU, the goal is not to replace DWARF, but rather
to have CTF serve as a "better than nothing" debug info format when
DWARF is not available.
It's worth noting that the LLVM toolchain does not support emitting CTF.
XNU uses ctfconvert to generate CTF from DWARF which is used for
testing.
Differential revision: https://reviews.llvm.org/D154862
