Summary:
When dwo support was introduced, it used a trick where debug info
entries were referenced by the offset of the compile unit in the main
file, but the die offset was relative to the dwo file. Although there
was some elegance to it, this representation was starting to reach its
breaking point:
- the fact that the skeleton compile unit owned the DWO file meant that
it was impossible (or at least hard and unintuitive) to support DWO
files containing more than one compile unit. These kinds of files are
produced by LTO for example.
- it made it impossible to reference any DIEs in the skeleton compile
unit (although the skeleton units are generally empty, clang still
puts some info into them with -fsplit-dwarf-inlining).
- (current motivation) it made it very hard to support type units placed
in DWO files, as type units don't have any skeleton units which could
be referenced in the main file
This patch addresses this problem by introducing an new
"dwo_num" field to the DIERef class, whose purpose is to identify the
dwo file. It's kind of similar to the dwo_id field in DWARF5 unit
headers, but while this is a 64bit hash whose main purpose is to catch
file mismatches, this is just a smaller integer used to indentify a
loaded dwo file. Currently, this is based on the index of the skeleton
compile unit which owns the dwo file, but it is intended to be
eventually independent of that (to support the LTO use case).
Simultaneously the cu_offset is dropped to conserve space, as it is no
longer necessary. This means we can remove the "BaseObjectOffset" field
from the DWARFUnit class. It also means we can remove some of the
workarounds put in place to support the skeleton-unit+dwo-die combo.
More work is needed to remove all of them, which is out of scope of this
patch.
Reviewers: JDevlieghere, clayborg, aprantl
Subscribers: mehdi_amini, dexonsmith, arphaman, lldb-commits
Differential Revision: https://reviews.llvm.org/D63428
llvm-svn: 364009
Recently I tried to port LLDB's lit configuration files over to use a
on the surface, but broke some cases that weren't broken before and also
exposed some additional problems with the old approach that we were just
getting lucky with.
When we set up a lit environment, the goal is to make it as hermetic as
possible. We should not be relying on PATH and enabling the use of
arbitrary shell commands. Instead, only whitelisted commands should be
allowed. These are, generally speaking, the lit builtins such as echo,
cd, etc, as well as anything for which substitutions have been
explicitly set up for. These substitutions should map to the build
output directory, but in some cases it's useful to be able to override
this (for example to point to an installed tools directory).
This is, of course, how it's supposed to work. What was actually
happening is that we were bringing in PATH and LD_LIBRARY_PATH and then
just running the given run line as a shell command. This led to problems
such as finding the wrong version of clang-cl on PATH since it wasn't
even a substitution, and flakiness / non-determinism since the
environment the tests were running in would change per-machine. On the
other hand, it also made other things possible. For example, we had some
tests that were explicitly running cl.exe and link.exe instead of
clang-cl and lld-link and the only reason it worked at all is because it
was finding them on PATH. Unfortunately we can't entirely get rid of
these tests, because they support a few things in debug info that
clang-cl and lld-link don't (notably, the LF_UDT_MOD_SRC_LINE record
which makes some of the tests fail.
The high level changes introduced in this patch are:
1. Removal of functionality - The lit test suite no longer respects
LLDB_TEST_C_COMPILER and LLDB_TEST_CXX_COMPILER. This means there is no
more support for gcc, but nobody was using this anyway (note: The
functionality is still there for the dotest suite, just not the lit test
suite). There is no longer a single substitution %cxx and %cc which maps
to <arbitrary-compiler>, you now explicitly specify the compiler with a
substitution like %clang or %clangxx or %clang_cl. We can revisit this
in the future when someone needs gcc.
2. Introduction of the LLDB_LIT_TOOLS_DIR directory. This does in spirit
what LLDB_TEST_C_COMPILER and LLDB_TEST_CXX_COMPILER used to do, but now
more friendly. If this is not specified, all tools are expected to be
the just-built tools. If it is specified, the tools which are not
themselves being tested but are being used to construct and run checks
(e.g. clang, FileCheck, llvm-mc, etc) will be searched for in this
directory first, then the build output directory.
3. Changes to core llvm lit files. The use_lld() and use_clang()
functions were introduced long ago in anticipation of using them in
lldb, but since they were never actually used anywhere but their
respective problems, there were some issues to be resolved regarding
generality and ability to use them outside their project.
4. Changes to .test files - These are all just replacing things like
clang-cl with %clang_cl and %cxx with %clangxx, etc.
5. Changes to lit.cfg.py - Previously we would load up some system
environment variables and then add some new things to them. Then do a
bunch of work building out our own substitutions. First, we delete the
system environment variable code, making the environment hermetic. Then,
we refactor the substitution logic into two separate helper functions,
one which sets up substitutions for the tools we want to test (which
must come from the build output directory), and another which sets up
substitutions for support tools (like compilers, etc).
6. New substitutions for MSVC -- Previously we relied on location of
MSVC by bringing in the entire parent's PATH and letting
subprocess.Popen just run the command line. Now we set up real
substitutions that should have the same effect. We use PATH to find
them, and then look for INCLUDE and LIB to construct a substitution
command line with appropriate /I and /LIBPATH: arguments. The nice thing
about this is that it opens the door to having separate %msvc-cl32 and
%msvc-cl64 substitutions, rather than only requiring the user to run
vcvars first. Because we can deduce the path to 32-bit libraries from
64-bit library directories, and vice versa. Without these substitutions
this would have been impossible.
Differential Revision: https://reviews.llvm.org/D54567
llvm-svn: 347216
The motivation for this is to be able to Dwarf index ability to look up
variables within a given compilation unit. It also fits in with the
patch in progress at D47939, which will add the ability to look up
funtions using file+line pairs.
The verification of which lldb-test options can be used together was
getting a bit unwieldy, so I moved the logic out into a separate
function.
llvm-svn: 334498
Pavel Labath