As long as possible, entire decoded frame sample vectors are moved into
the output vector, leading to up to 20% speedups by avoiding memmoves on
take_first.
Previously, Vector::extend for a moved vector would move the other
vector into this vector if this vector was empty, thereby throwing away
existing allocated capacity. Therefore, this commit allows the move to
only happen if this vector's capacity is too small to fit the other
vector. This will also alleviate bugs where callers relied on the
capacity to never shrink with calls to unchecked_append, extend and the
like.
This mirrors the existence of append() for data pointers and is very
useful when the program needs to have a guarantee of no allocations,
as is necessary for real-time audio.
Previously, a libc-like out-of-line error information was used in the
loader and its plugins. Now, all functions that may fail to do their job
return some sort of Result. The universally-used error type ist the new
LoaderError, which can contain information about the general error
category (such as file format, I/O, unimplemented features), an error
description, and location information, such as file index or sample
index.
Additionally, the loader plugins try to do as little work as possible in
their constructors. Right after being constructed, a user should call
initialize() and check the errors returned from there. (This is done
transparently by Loader itself.) If a constructor caused an error, the
call to initialize should check and return it immediately.
This opportunity was used to rework a lot of the internal error
propagation in both loader classes, especially FlacLoader. Therefore, a
couple of other refactorings may have sneaked in as well.
The adoption of LibAudio users is minimal. Piano's adoption is not
important, as the code will receive major refactoring in the near future
anyways. SoundPlayer's adoption is also less important, as changes to
refactor it are in the works as well. aplay's adoption is the best and
may serve as an example for other users. It also includes new buffering
behavior.
Buffer also gets some attention, making it OOM-safe and thereby also
propagating its errors to the user.
This consists of two changes: First, a utility function create_empty
allows the user to quickly create an empty buffer. Second, most creation
functions now return a NonnullRefPtr, as their failure causes a VERIFY
crash anyways.
Decoding the residual in FLAC subframes is by far the most I/O-heavy
operation in FLAC decoding, as the residual data makes up the majority
of subframe data in LPC subframes. As the residual consists of many
Rice-encoded numbers with different bit sizes for differently large
numbers, the residual decoder frequently reads only one or two bytes at
a time. As we use a normal FileInputStream, that directly translates to
many calls to the read() syscall. We can see that the I/O overhead while
FLAC decoding is quite large, and much time is spent in the read()
syscall's kernel code.
This is optimized by using a Buffered<FileInputStream> instead, leading
to 4K blocks being read at once and a large reduction in I/O overhead.
Benchmarking with the new abench utility gives a 15-20% speedup on
identical files, usually pushing FLAC decoding to 10-15x realtime speed
on common sample rates.
If we have the LLVM port installed, CMake might pick up some of the
tools installed as part of it (`llvm-ar`, `llvm-strip`, etc.) instead of
the ones belonging to the host toolchain. These, of course, can't be run
on the host platform, so builds would eventually fail. This made it
impossible to rebuild the LLVM toolchain.
We now set these variables explicitly when compiling the LLVM runtime
libraries in order to avoid this issue.
With this update, we now use our custom `serenity` Clang target, which
means that all system-specific compilation options (e.g. default PIE,
header search paths) will be handled automatically.
This port has been tested to build `Source/little` on all 4
toolchain-architecture pairs. Furthermore, `lib(std)c++` headers are
picked up correctly and our AK headers can be included without any
issues.
Due to recent kernel fixes related to memory-mapped files, the LLD
linker can now be used by default, so there's no need to also build the
GCC port alongside this.
Although our patches cover building libLLVM as a shared library, this is
currently not enabled by default, as DynamicLoader is very slow in
dealing with such a large number of relocations.
With this, we can now compile C++ programs with the LLVM port without
having to jump through hooks to build libc++ because it can't be
cross-compiled with our GNU toolchain.
If we do this, the LLVM port's Clang will pick up these paths, so we
won't have to compile libc++ twice. This does increase the size of
_disk_image by 5 MB, but that shouldn't be a problem.
POSIX mandates that the macros contained in `stdint.h` be suitable for
use by the C preprocessor.
If we write `((size_t)-1)`, the C preprocessor will just skip the cast
and treat the value as `-1`. This means that we end up taking the wrong
branch in an `#if` directive like `#if SIZE_MAX > UINT32_MAX`.
This fixes building the LLVM port on i686.
x86_64 is an LP64 platform, so its `uint64_t` type is defined to be
`unsigned long`, not `unsigned long long` like on i686. This means that
the `UL` literal suffix should be used instead of `ULL`.
Furthermore, `uintptr_t` is 64 bits wide on x86_64, so defining
`UINTPTR_MAX` to be `UINT32_MAX` is also not correct.
This will come in handy if we want to use the LLVM port with a GNU host
compiler.
As of version 13, libc++ uses `__attribute__((using_if_exists))` to
import global LibC functions into the `std` namespace, which allows some
symbols to be absent. GCC does not support this attribute, so it fails
to build libc++ due to some obscure `wchar.h` functions. This means that
cross-compiling libc++ is not possible; and on-target builds would be
tedious, so we'll be better off using the toolchain's `libstdc++`.
In order to propagate errors that occur during UI setup, we have to move
all that logic out of widget/window subclass constructors. This is a
first attempt at doing that, for GUI::SettingsWindow.
