When investigating various things, we often have a file offset
and what to know what's in the PDB at that address. For example
we may be doing a binary comparison of two LLD-generated PDBs
to look for sources of non-determinism, or we may wish to compare
an LLD-generated PDB with a Microsoft generated PDB for sources
of byte-for-byte incompatibility. In these cases, we can do a
binary diff of the two files, and once we find a mismatched byte
we can use explain to figure out what that byte is, immediately
honining in on the problem.
This patch implements this by trying to narrow the meaning of
a particular file offset down as much as possible.
Differential Revision: https://reviews.llvm.org/D44959
llvm-svn: 328799
This has been made obsolete by the fact that almost all of the
things it previously checked for are no longer relevant since
we can just compare bytes in a lot of places.
llvm-svn: 328562
When investigating bugs in PDB generation, the first step is
often to do the same link with link.exe and then compare PDBs.
But comparing PDBs is hard because two completely different byte
sequences can both be correct, so it hampers the investigation when
you also have to spend time figuring out not just which bytes are
different, but also if the difference is meaningful.
This patch fixes a couple of cases related to string table emission,
hash table emission, and the order in which we emit strings that
makes more of our bytes the same as the bytes generated by MS PDBs.
Differential Revision: https://reviews.llvm.org/D44810
llvm-svn: 328348
This is still failing on a different bot this time due to some
issue related to hashing absolute paths. Reverting until I can
figure it out.
llvm-svn: 328014
The issue causing this to fail in certain configurations
should be fixed.
It was due to the fact that DIA apparently expects there to be
a null string at ID 1 in the string table. I'm not sure why this
is important but it seems to make a difference, so set it.
llvm-svn: 328002
Natvis is a debug language supported by Visual Studio for
specifying custom visualizers. The /NATVIS option is an
undocumented link.exe flag which will take a .natvis file
and "inject" it into the PDB. This way, you can ship the
debug visualizers for a program along with the PDB, which
is very useful for postmortem debugging.
This is implemented by adding a new "named stream" to the
PDB with a special name of /src/files/<natvis file name>
and simply copying the contents of the xml into this file.
Additionally, we need to emit a single stream named
/src/headerblock which contains a hash table of embedded
files to records describing them.
This patch adds this functionality, including the /NATVIS
option to lld-link.
Differential Revision: https://reviews.llvm.org/D44328
llvm-svn: 327895
We have llvm-readobj for dumping CodeView from object files, and
llvm-pdbutil has always been more focused on PDB. However,
llvm-pdbutil has a lot of useful options for summarizing debug
information in aggregate and presenting high level statistical
views. Furthermore, it's arguably better as a testing tool since
we don't have to write tests to conform to a state-machine like
structure where you match multiple lines in succession, each
depending on a previous match. llvm-pdbutil dumps much more
concisely, so it's possible to use single-line matches in many
cases where as with readobj tests you have to use multi-line
matches with an implicit state machine.
Because of this, I'm adding object file support to llvm-pdbutil.
In fact, this mirrors the cvdump tool from Microsoft, which also
supports both object files and pdb files. In the future we could
perhaps rename this tool llvm-cvutil.
In the meantime, this allows us to deep dive into object files
the same way we already can with PDB files.
llvm-svn: 312358
This adds a new command line option, -udt-stats, which breaks
down the stats of S_UDT records. These are one of the biggest
contributors to the size of /DEBUG:FASTLINK PDBs, so they need
some additional tools to be able to analyze their usage. This
option will dig into each S_UDT record and determine what kind
of record it points to, and then break down the statistics by
the target type. The goal here is to identify how our object
files differ from MSVC object files in S_UDT records, so that
we can output fewer of them and reach size parity.
llvm-svn: 312276
This adds support for dumping a summary of module symbols
and CodeView debug chunks. This option prints a table for
each module of all of the symbols that occurred in the module
and the number of times it occurred and total byte size. Then
at the end it prints the totals for the entire file.
Additionally, this patch adds the -jmc (just my code) option,
which suppresses modules which are from external libraries or
linker imports, so that you can focus only on the object files
and libraries that originate from your own source code.
llvm-svn: 311338
Image section headers are stored in the DBI stream, but we
had no way to dump them. This patch adds dumping support,
along with some tests that LLD actually dumps them correctly.
Differential Revision: https://reviews.llvm.org/D36332
llvm-svn: 310107
Often something interesting (like a symbol) is in a particular
module, and you don't want to dump symbols from all other 300
modules to see the one you want. This adds a -modi option so that
we only dump the specified module.
llvm-svn: 310000
Sometimes the normal module equivalence detection algorithm doesn't
quite work. For example, you might build the same program with
MSVC and clang-cl, outputting to different object files, exes, and
PDBs, then compare them. If the object files have different names
though, then they won't be treated as equivalent. This way we
can force specific module indices to be treated as equivalent.
llvm-svn: 309983
Recently problems have been discovered in the way we write the FPM
(free page map). In order to fix this, we first need to establish
a baseline about what a correct FPM looks like using an MSVC
generated PDB, so that we can then make our own generated PDBs
match. And in order to do this, the dumper needs a mode where it
can dump an FPM so that we can write tests for it.
This patch adds a command to dump the FPM, as well as a test against
a known-good PDB.
llvm-svn: 309894
The PDB "symbol stream" actually contains symbol records for the publics
and the globals stream. The globals and publics streams are essentially
hash tables that point into a single stream of records. In order to
match cvdump's behavior, we need to only dump symbol records referenced
from the hash table. This patch implements that, and then implements
global stream dumping, since it's just a subset of public stream
dumping.
Now we shouldn't see S_PROCREF or S_GDATA32 records when dumping
publics, and instead we should see those record in the globals stream.
llvm-svn: 309066
This includes the hash table, the address map, and the thunk table and
section offset table. The last two are only used for incremental
linking, which LLD doesn't support, so they are less interesting. The
hash table is particularly important to get right, since this is the one
of the streams that debuggers use to translate addresses to symbols.
llvm-svn: 308764
This was originally reverted because of two issues.
1) Printing ANSI color escape codes even when outputting to
a file
2) Module name comparisons were failing when comparing a PDB
generated on one machine to a PDB generated on another
machine.
I attempted to fix#2 by adding command line options which let
you specify prefixes to strip from the beginning of embedded
paths, which effectively lets us specify a path to "base" each
PDB from and only compare the parts under the base. But this is
tricky because PDB paths always use Windows path syntax, even
when they are created on non-Windows hosts. A problem still
existed when constructing the prefix to strip, where we were
accidentally using a host-specific path separator instead of
a Windows path separator.
This resubmission fixes the issue on Linux (and I have verified
that the test now passes on Linux).
llvm-svn: 307571
A test was checked in on Friday that worked by checking in an
object file and PDB generated locally by MSVC, and then having
the test run lld-link on the object file and diffing LLD's PDB
against the checked in PDB.
This failed because part of the diffing algorithm involves
determining if two modules are the same, and if so drilling into
the module and diffing individual fields of the module. The
only thing we can use to make this determination though is the
"name" of the module, which is a path to where the module (obj
file) was read from on the machine where it was linked. This
fails for obvious reasons when comparing a PDB generated on one
machine to a PDB on another machine.
The fix employed here is to add two command line options to the
diff subcommand, which allow the user to specify a "binary root
path". The bin root path, if specified, is stripped from the
beginning of any embedded PDB paths. The test is updated to
specify the user's local test output directory for the left
PDB, and is hardcoded to the location where the original PDB
was created for the right PDB. This way all the equivalence
comparisons should succeed.
llvm-svn: 307555
A couple of things were different about our generated PDBs.
1) We were outputting the wrong Version on the PDB Stream.
The version we were setting was newer than what MSVC is setting.
It's not clear what the implications are, but we change LLD
to use PdbImplVC70, as MSVC does.
2) For the optional debug stream indices in the DBI Stream, we
were outputting 0 to mean "the stream is not present". MSVC
outputs uint16_t(-1), which is the "correct" way to specify
that a stream is not present. So we fix that as well.
3) We were setting the PDB Stream signature to 0. This is supposed
to be the result of calling time(nullptr). Although this leads
to non-deterministic builds, a better way to solve that is by
having a command line option explicitly for generating a
reproducible build, and have the default behavior of lld-link
match the default behavior of link.
To test this, I'm making use of the new and improved `pdb diff`
sub command. To make it suitable for writing tests against, I had
to modify the diff subcommand slightly to print less verbose output.
Previously it would always print | <column> | <value1> | <value2> |
which is quite verbose, and the values are fragile. All we really
want to know is "did we produce the same value as link?" So I added
command line options to print a single character representing the
result status (different, identical, equivalent), and another to
hide the value display. Note that just inspecting the diff output
used to write the test, you can see some things that are obviously
wrong. That is just reflective of the fact that this is the state
of affairs today, not that we're asserting that this is "correct".
We can use this as a starting point to discover differences, fix
them, and update the test.
Differential Revision: https://reviews.llvm.org/D35086
llvm-svn: 307422
Previously we had the -type-index option which would dump the record of
a single, but we had no way to follow the dependency graph backwards and
also dump all dependent types.
Having this option makes test-writing better, because we can limit the
test to only those records that are of importance for the thing we're
trying to test, which allows us to use things like CHECK-NEXT to reduce
fragility.
Differential Revision: https://reviews.llvm.org/D34899
llvm-svn: 306852
This is useful when you want to look at a specific chunk of a
stream or look for discontinuities, and you need to know the
list of blocks occupied by a stream.
llvm-svn: 306150
This patch dumps the raw bytes of the pdb name map which contains
the mapping of stream name to stream index for the string table
and other reserved streams.
llvm-svn: 306148
Normally we can only make sense of the content of a PDB in terms
of streams and blocks, but in some cases it may be useful to dump
bytes at a specific absolute file offset. For example, if you
know that some interesting data is at a particular location and
you want to see some surrounding data.
llvm-svn: 306146
This idea originally came about when I was doing some deep
investigation of why certain bytes in a PDB that we round-tripped
differed from their original bytes in the source PDB. I found
myself having to hack up the code in many places to dump the
bytes of this substream, or that record. It would be nice if
we could just do this for every possible stream, substream,
debug chunk type, etc.
It doesn't make sense to put this under dump because there's just
so many options that would detract from the more common use case
of just dumping deserialized records. So making a new subcommand
seems like the most logical course of action. In doing so, we
already have two command line options that are suitable for this
new subcommand, so start out by moving them there.
llvm-svn: 306056
Now you run llvm-pdbutil dump <options>. This is a followup
after having renamed the tool, whereas before raw was obviously
just the style of dumping, whereas now "dump" is the action to
perform with the "util".
llvm-svn: 306055
This resubmits commit c0c249e9f2ef83e1d1e5f166b50673d92f3579d7.
It was broken due to some weird template issues, which have
since been fixed.
llvm-svn: 305517
This reverts commit 83ea17ebf2106859a51fbc2a86031b44d33696ad.
This is failing due to some strange template problems, so reverting
until it can be straightened out.
llvm-svn: 305505
After some internal discussions, we agreed that the raw output style had
outlived its usefulness. It was originally created before we had even
thought of dumping to YAML, and it was intended to give us some insight
into the internals of a PDB file. Now we have YAML mode which does
almost exactly this but is more powerful in that it can round-trip back
to a PDB, which the raw mode could not do. So the raw mode had become
purely a maintenance burden.
One option was to just delete it. However, its original goal was to be
as readable as possible while staying close to the "metal" - i.e.
presenting the output in a way that maps directly to the underlying file
format. We don't actually need that last requirement anymore since it's
covered by the yaml mode, so we could repurpose "raw" mode to actually
just be as readable as possible.
This patch implements about 80% of the functionality previously in raw
mode, but in a completely different style that is more akin to what
cvdump outputs. Records are very compressed, often times appearing on
just one line. One nice thing about this is that it makes full record
matching easier, because you can grep for indices, names, and leaf types
on a single line often.
See the tests for some examples of what the new output looks like.
Note that this patch actually regresses the functionality of raw mode in
a few areas, but only because the patch was already unreasonably large
and going 100% would have been even worse. Specifically, this patch is
missing:
The ability to dump module debug subsections (checksums, lines, etc)
The ability to dump section headers
Aside from that everything is here. While goign through the tests fixing
them all up, I found many duplicate tests. They've been deleted. In
subsequent patches I will go through and re-add the missing
functionality.
Differential Revision: https://reviews.llvm.org/D34191
llvm-svn: 305495
This is to reflect the evolving nature of the tool as being
useful for more than just dumping PDBs, as it can do many other
things.
Differential Revision: https://reviews.llvm.org/D34062
llvm-svn: 305106
Zachary Turner