This patch is to rewrite FileOutputBuffer as two separate classes;
one for file-backed output buffer and the other for memory-backed
output buffer. I think the new code is easier to follow because two
different implementations are now actually separated as different
classes.
Unlike the previous implementation, the class that does not replace the
final output file using rename(2) does not create a temporary file at
all. Instead, it allocates memory using mmap(2) and use it. I think
this is an improvement because it is now guaranteed that the temporary
memory region doesn't trigger any I/O and there's now zero chance to
leave a temporary file behind. Also, it shouldn't impose new restrictions
because were using mmap IO too.
Differential Revision: https://reviews.llvm.org/D39449
llvm-svn: 317127
When writing to a non regular file we cannot rename to it. Since we
have to write, we may as well create a temporary file to avoid trying
to create an unique file in /dev when trying to write to /dev/null.
llvm-svn: 291485
The idea of this patch is to turn llvm/Support/system_error.h into a
transitional header that just brings in the erorr_code api to the llvm
namespace. I will remove it shortly afterwards.
The cases where the general idea needed some tweaking:
* std::errc is a namespace in msvc, so we cannot use "using std::errc". I could
add an #ifdef, but there were not that many uses, so I just added std:: to
them in this patch.
* Template specialization had to be moved to the std namespace in this
patch set already.
* The msvc implementation of default_error_condition doesn't seem to
provide the same transformations as we need. Not too surprising since
the standard doesn't actually say what "equivalent" means. I fixed the
problem by keeping our old mapping and using it at error_code
construction time.
Despite these shortcomings I think this is still a good thing. Some reasons:
* The different implementations of system_error might improve over time.
* It removes 925 lines of code from llvm already.
* It removes 6313 bytes from the text segment of the clang binary when
it is built with gcc and 2816 bytes when building with clang and
libstdc++.
llvm-svn: 210687
This will allow external callers of these functions to switch over time
rather than forcing a breaking change all a once. These particular
functions were determined by building clang/lld/lldb.
llvm-svn: 202959
Since the llvm::sys::fs::map_file_pages() support function it relies on
is not yet implemented on Windows, the unit tests for FileOutputBuffer
are currently conditionalized to run only on unix.
llvm-svn: 161099
