Previously we would read a PDB, then write some of it back out,
but write the directory, super block, and other pertinent metadata
back out unchanged. This generates incorrect PDBs since the amount
of data written was not always the same as the amount of data read.
This patch changes things to use the newly introduced `MsfBuilder`
class to write out a correct and accurate set of Msf metadata for
the data *actually* written, which opens up the door for adding and
removing type records, symbol records, and other types of data to
an existing PDB.
llvm-svn: 275627
This adds method and tests for writing to a PDB stream. With
this, even a PDB stream which is discontiguous can be treated
as a sequential stream of bytes for the purposes of writing.
Reviewed By: ruiu
Differential Revision: http://reviews.llvm.org/D21157
llvm-svn: 272369
In order to efficiently write PDBs, we need to be able to make a
StreamWriter class similar to a StreamReader, which can transparently deal
with writing to discontiguous streams, and we need to use this for all
writing, similar to how we use StreamReader for all reading.
Most discontiguous streams are the typical numbered streams that appear in
a PDB file and are described by the directory, but the exception to this,
that until now has been parsed by hand, is the directory itself.
MappedBlockStream works by querying the directory to find out which blocks
a stream occupies and various other things, so naturally the same logic
could not possibly work to describe the blocks that the directory itself
resided on.
To solve this, I've introduced an abstraction IPDBStreamData, which allows
the client to query for the list of blocks occupied by the stream, as well
as the stream length. I provide two implementations of this: one which
queries the directory (for indexed streams), and one which queries the
super block (for the directory stream).
This has the side benefit of vastly simplifying the code to parse the
directory. Whereas before a mini state machine was rolled by hand, now we
simply use FixedStreamArray to read out the stream sizes, then build a
vector of FixedStreamArrays for the stream map, all in just a few lines of
code.
Reviewed By: ruiu
Differential Revision: http://reviews.llvm.org/D21046
llvm-svn: 271982
To facilitate this, a couple of changes had to be made:
1. `ModuleSubstream` got moved from `DebugInfo/PDB` to
`DebugInfo/CodeView`, and various codeview related types are defined
there. It turns out `DebugInfo/CodeView/Line.h` already defines many of
these structures, but this is really old code that is not endian aware,
doesn't interact well with `StreamInterface` and not very helpful for
getting stuff out of a PDB. Eventually we should migrate the old readobj
`COFFDumper` code to these new structures, or at least merge their
functionality somehow.
2. A `ModuleSubstream` visitor is introduced. Depending on where your
module substream array comes from, different subsets of record types can
be expected. We are already hand parsing these substream arrays in many
places especially in `COFFDumper.cpp`. In the future we can migrate these
paths to the visitor as well, which should reduce a lot of code in
`COFFDumper.cpp`.
Differential Revision: http://reviews.llvm.org/D20936
Reviewed By: ruiu, majnemer
llvm-svn: 271621
StreamRef was designed to be a thin wrapper over an abstract
stream interface that could itself be treated the same as any
other stream interface. For this reason, it inherited publicly
from StreamInterface, and stored a StreamInterface* internally.
But StreamRef was also designed to be lightweight and easily
copyable, similar to ArrayRef. This led to two misuses of
the classes.
1) When creating a StreamRef A from another StreamRef B, it was
possible to end up with A storing a pointer to B, even when
B was a temporary object, leading to use after free.
2) The above situation could be repeated ad nauseum, so that
A stores a pointer to B, which itself stores a pointer to
another StreamRef C, and so on and so on, creating an
unnecessarily level of nesting depth.
This patch removes the public inheritance relationship between
StreamRef and StreamInterface, making it so that we can never
accidentally convert a StreamRef to a StreamInterface.
llvm-svn: 271570
This converts remaining uses of ByteStream, which was still
left in the symbol stream and type stream, to using the new
StreamInterface zero-copy classes.
RecordIterator is finally deleted, so this is the only way left
now. Additionally, more error checking is added when iterating
the various streams.
With this, the transition to zero copy pdb access is complete.
llvm-svn: 271101
Due to differences in template instantiation rules, it is not
portable to static_assert(false) inside of an invalid specialization
of a template. Instead I just =delete the method so that it can't
be used, and leave a comment that it must be explicitly specialized.
llvm-svn: 271027
This reverts commit r271024 due to error: static_assert failed
"You must either provide a specialization of VarStreamArrayExtractor
or a custom extractor"
llvm-svn: 271026
This reduces the amount of memory used by llvm-pdbdump by roughly
1/3 of the size of the PDB file.
Differential Revision: http://reviews.llvm.org/D20724
Reviewed By: ruiu
llvm-svn: 271025
type_traits header in libstdc++ 4.8 does not define is_trivially_contructible
so the code doesn't compile with it.
In this file we are using the trait for assertion to provide a better
error message. Removing it doesn't change the meaning of the code.
Differential Revision: http://reviews.llvm.org/D20719
llvm-svn: 270957
PDBs can be extremely large. We're already mapping the entire
PDB into the process's address space, but to make matters worse
the blocks of the PDB are not arranged contiguously. So, when
we have something like an array or a string embedded into the
stream, we have to make a copy. Since it's convenient to use
traditional data structures to iterate and manipulate these
records, we need the memory to be contiguous.
As a result of this, we were using roughly twice as much memory
as the file size of the PDB, because every stream was copied
out and re-stitched together contiguously.
This patch addresses this by improving the MappedBlockStream
to allocate from a BumpPtrAllocator only when a read requires
a discontiguous read. Furthermore, it introduces some data
structures backed by a stream which can iterate over both
fixed and variable length records of a PDB. Since everything
is backed by a stream and not a buffer, we can read almost
everything from the PDB with zero copies.
Differential Revision: http://reviews.llvm.org/D20654
Reviewed By: ruiu
llvm-svn: 270951
