Now that llvm::support::endianness has been renamed to
llvm::endianness, we can directly get endianness from the llvm
namespace.  We don't need to go through support.

Most PDB fields on disk are 32-bit but describe the file in terms of MSF
blocks, which are 4 kiB by default.

So PDB files can be a bit larger than 4 GiB, and much larger if you create them
with a block size > 4 kiB.

This is a first (necessary, but by far not not sufficient) step towards
supporting such PDB files.  Now we don't truncate in-memory file offsets (which
are in terms of bytes, not in terms of blocks).

No effective behavior change. lld-link will still error out if it were to
produce PDBs > 4 GiB.

Differential Revision: https://reviews.llvm.org/D109923

 - uninitialized variables
 - documention warnings
 - shadow variable names

Summary:
This patch adds support for ULEB128 and SLEB128 encoding and decoding to
BinaryStreamWriter and BinaryStreamReader respectively.

Support for ULEB128/SLEB128 will be used for eh-frame parsing in the JITLink
library currently under development (see https://reviews.llvm.org/D58704).

Reviewers: zturner, dblaikie

Subscribers: kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60810

llvm-svn: 358584

to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636

This is essentially just a BinaryStreamRef packaged with an
offset and the logic for reading one is no different than the
logic for reading a BinaryStreamRef, except that we save the
current offset.

llvm-svn: 306122

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33566

llvm-svn: 304225

Previously it would do a character by character search for a null
terminator, to account for the fact that an arbitrary stream need not
store its data contiguously so you couldn't just do a memchr. However, the
stream API has a function which will return the longest contiguous chunk
without doing a copy, and by using this function we can do a memchr on the
individual chunks. For certain types of streams like data from object
files etc, this is guaranteed to find the null terminator with only a
single memchr, but even with discontiguous streams such as
MappedBlockStream, it's rare that any given string will cross a block
boundary, so even those will almost always be satisfied with a single
memchr.

This optimization is worth a 10-12% reduction in link time (4.2 seconds ->
3.75 seconds)

Differential Revision: https://reviews.llvm.org/D33503

llvm-svn: 303918

llvm-svn: 303297

Often you have an array and you just want to use it.  With the current
design, you have to first construct a `BinaryByteStream`, and then create
a `BinaryStreamRef` from it.  Worse, the `BinaryStreamRef` holds a pointer
to the `BinaryByteStream`, so you can't just create a temporary one to
appease the compiler, you have to actually hold onto both the `ArrayRef`
as well as the `BinaryByteStream` *AND* the `BinaryStreamReader` on top of
that.  This makes for very cumbersome code, often requiring one to store a
`BinaryByteStream` in a class just to circumvent this.

At the cost of some added complexity (not exposed to users, but internal
to the library), we can do better than this.  This patch allows us to
construct `BinaryStreamReaders` and `BinaryStreamWriters` directly from
source data (e.g. `StringRef`, `MutableArrayRef<uint8_t>`, etc).  Not only
does this reduce the amount of code you have to type and make it more
obvious how to use it, but it solves real lifetime issues when it's
inconvenient to hold onto a `BinaryByteStream` for a long time.

The additional complexity is in the form of an added layer of indirection.
Whereas before we simply stored a `BinaryStream*` in the ref, we now store
both a `BinaryStream*` **and** a `std::shared_ptr<BinaryStream>`.  When
the user wants to construct a `BinaryStreamRef` directly from an
`ArrayRef` etc, we allocate an internal object that holds ownership over a
`BinaryByteStream` and forwards all calls, and store this in the
`shared_ptr<>`.  This also maintains the ref semantics, as you can copy it
by value and references refer to the same underlying stream -- the one
being held in the object stored in the `shared_ptr`.

Differential Revision: https://reviews.llvm.org/D33293

llvm-svn: 303294