Summary:
This is motivated by D63591, where we realized that there isn't a really
good way of telling whether a DataExtractor is reading actual data, or
is it just returning default values because it reached the end of the
buffer.
This patch resolves that by providing a new "Cursor" class. A Cursor
object encapsulates two things:
- the current position/offset in the DataExtractor
- an error object
Storing the error object inside the Cursor enables one to use the same
pattern as the std::{io}stream API, where one can blindly perform a
sequence of reads and only check for errors once at the end of the
operation. Similarly to the stream API, as soon as we encounter one
error, all of the subsequent operations are skipped (return default
values) too, even if the would suceed with clear error state. Unlike the
std::stream API (but in line with other llvm APIs), we force the error
state to be checked through usage of llvm::Error.
Reviewers: probinson, dblaikie, JDevlieghere, aprantl, echristo
Subscribers: kristina, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63713
llvm-svn: 370042
Using 64-bit offsets is required to fully implement 64-bit DWARF.
As these classes are used in many different libraries they should
temporarily support both 32- and 64-bit offsets.
Differential Revision: https://reviews.llvm.org/D64006
llvm-svn: 368013
Should've been NFC, but turns out DataExtractor had better test coverage
for decoding SLEB128 than the decodeSLEB128 did - revealing a couple of
bugs (one in the error handling, another in sign extension). So fixed
those to get the DataExtractor tests passing again.
llvm-svn: 364253
Summary:
These functions are documented as not modifying the offset argument if
the extraction fails (just like other DataExtractor functions). However,
while reviewing D63591 we discovered that this is not the case -- if the
function reaches the end of the data buffer, it will just return the
value parsed until that point and set offset to point to the end of the
buffer.
This fixes the functions to act as advertised, and adds a regression
test.
Reviewers: dblaikie, probinson, bkramer
Subscribers: kristina, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63645
llvm-svn: 364169
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
I will remove the isBigEndianHost function once I update clang.
The ifdef logic is designed to
* not use configure/cmake to avoid breaking -arch i686 -arch ppc.
* default to little endian
* be as small as possible
It looks like sys/endian.h is the preferred header on most modern BSD systems,
but it is better to change this in a followup patch as machine/endian.h is
available on FreeBSD, OpenBSD, NetBSD and OS X.
llvm-svn: 179527
It is an endian-aware helper that can read data from a StringRef. It will
come in handy for DWARF parsing. This class is inspired by LLDB's
DataExtractor, but is stripped down to the bare minimum needed for DWARF.
Comes with unit tests!
llvm-svn: 139626
Pavel Labath