Some downstream projects need to adapt the libjpeg-turbo source code to
non-CMake build systems, and the use of CMake object libraries made that
difficult. Referring to #754, the use of CMake object libraries also
caused the libjpeg-turbo libraries to contain duplicate object names,
which caused problems with certain development tools. This commit
modifies the build system so that it uses wrappers, rather than CMake
object libraries, to compile source files for multiple data precisions.
For convenience, the wrappers are included in the source tree, but they
can be re-generated by building the "wrappers" target.
In addition to facilitating downstream integration, using wrappers
improves code readability, since multiple data precisions are now
handled at the source code level instead of at the build system level.
Since this will be pushed to a bug-fix release, the goal was to avoid
changing any existing source code. A future major release of
libjpeg-turbo may restructure the libjpeg API source code so that only
the functions that need to be compiled for multiple data precisions are
wrapped. (That is how the TurboJPEG API source code is structured.)
Closes#817
The build system originally force-enabled the maximum optimization level
(-O3) with GCC because it significantly improved the performance of the
C Huffman encoder on x86 platforms. Since libjpeg-turbo 1.5.x, the
Huffman encoder has been SIMD-accelerated on x86 and Arm platforms, and
in my testing on various Intel CPUs, the difference between -O2 and -O3
is no longer statistically significant. However, on certain Arm CPUs, I
observe that grayscale decompression slows down by 16-27% with -O2 vs.
-O3. Although modern versions of CMake use -O3 as the default
optimization level for Release builds, -O2 is still the default
optimization level for RelWithDebInfo builds. Thus, I am reluctant to
change the default behavior of our build system. However, referring
to #815, some users observe better performance with -O2 vs. -O3 on other
Arm CPUs, so the build system needs to allow users to override the
default behavior.
Closes#815
AppVeyor ran our CI build when both branches and tags were pushed. This
is necessary to support signing with SignPath.io, since we only sign
releases and not pre-releases. However, due to an oversight in
9af8cca75c, the global on: dictionary
excluded tag pushes.
To simulate the previous AppVeyor CI environment:
- Run all jobs regardless of whether a branch or a tag was pushed.
- Use the if: key to exclude all jobs except "windows" from tag pushes.
- Use Visual Studio 2022 for CI builds.
- Rename installers to clearly distinguish x86, x64, and Arm64 versions.
NOTE: The Windows/Arm installer uses the same internal name and install
directory as the Windows/x64 installer. That is consistent with the
behavior of the Linux packages. Because the installer places
turbojpeg.dll into C:\WINDOWS\System32, it would normally be impossible
to co-install the x64 and Arm64 versions anyhow. (That can still be
accomplished. You just have to use 7-Zip to extract one of the
installers into a non-default directory.)
The ubuntu-20.04 hosted runner image is going away on April 1, and newer
versions of Ubuntu can build but not run x32 binaries. The x32 ABI
seems to be mostly dead, but we can still regression test x32 support
using a local Ubuntu 20.04 VM if necessary. (That shouldn't be
necessary unless the x86-64 SIMD extensions change at some point in the
future.)
If a hypothetical calling application does something really stupid and
changes cinfo->data_precision after calling jpeg_start_*compress(), then
the precision-specific methods called by jpeg_write_scanlines(),
jpeg_write_raw_data(), jpeg_finish_compress(), jpeg_read_scanlines(),
jpeg_read_raw_data(), or jpeg_start_output() may not be initialized.
Ensure that the first precision-specific method (which will always be
cinfo->main->process_data*(), cinfo->coef->compress_data*(), or
cinfo->coef->decompress_data()) called by any global function that may
be called after jpeg_start_*compress() is initialized and non-NULL.
This increases the likelihood (but does not guarantee) that a
hypothetical stupid calling application will fail gracefully rather than
segfault if it changes cinfo->data_precision after calling
jpeg_start_*compress(). A hypothetical stupid calling application can
still bork itself by changing cinfo->data_precision after initializing
the source manager but before calling jpeg_start_compress(), or after
initializing the destination manager but before calling
jpeg_start_decompress().
As with x86-64, the Power ISA basically implements 64-bit instructions
as extensions of their 32-bit counterparts. Thus, 64-bit Power ISA CPUs
can natively execute legacy 32-bit PowerPC instructions when running in
big-endian mode. Most Power ISA support has shifted (pun intended) to
little-endian mode, so there are few remaining operating systems that
support big-endian mode. Debian is one of them, however (albeit
unofficially.)
Unlike other versions of Clang 14.0.0, AppleClang 14.0.0 in Xcode 14.2
retains the old -ffp-contract=off default. Apple didn't adopt
-ffp-contract=on as the default until Xcode 14.3 (AppleClang 14.0.3.)
This has been confirmed in the Xcode 14.3 release notes.
We use a standard set of strict compiler warnings with Clang and GCC to
continuously test and maintain C89 conformance in the libjpeg API code.
However, SIMD extensions need not comply with that. The AltiVec code
specifically uses some C99isms, so disable -Wc99-extensions and
-Wpedantic in the scope of that code. Also disable -Wshadow, because
I'm too lazy to fix the TRANSPOSE() macro. Also
use #ifdef __BIG_ENDIAN__ and #if defined(__BIG_ENDIAN__) instead
of #if __BIG_ENDIAN__
We use a standard set of strict compiler warnings with Clang and GCC to
continuously test and maintain C89 conformance in the libjpeg API code.
However, SIMD extensions need not comply with that. The Neon code
specifically uses some C99isms, so disable
-Wdeclaration-after-statement, -Wc99-extensions, and -Wpedantic in the
scope of that code. Also modify the Neon feature tests so that they
will succeed if any of the aforementioned compiler warnings are enabled.
Rename the ARMV8_BUILD CMake variable to SECONDARY_BUILD, and modify the
makemacpkg script so that it allows any architecture in a primary or
secondary build. The idea is that Apple Silicon users can package an
arm64 primary build and a secondary x86_64 build, and Intel users can
package an x86_64 primary build and a secondary arm64 build, using the
same procedure.
Also simplify the iOS build instructions, using the
CMAKE_OSX_ARCHITECTURES variable rather than a toolchain.
Since libjpeg-turbo does not support Exif, the only way it can embed
density information in a JPEG image is by using the JFIF marker, which
is only written if the JPEG colorspace is YCbCr or grayscale.
(Referring to the conversation under #793, we may need to further
restrict that to 8-bit-per-sample JPEG images, because the JFIF spec
requires 8-bit data precision.)
- Due to an oversight, a113506d17
(libjpeg-turbo 1.4 beta1) effectively made the call to
std_huff_tables() in jpeg_set_defaults() a no-op if the Huffman tables
were previously defined, which made it impossible to disable Huffman
table optimization or progressive mode if they were previously enabled
in the same API instance. std_huff_tables() retains its previous
behavior for decompression instances, but it now force-enables the
standard (baseline) Huffman tables for compression instances.
- Due to another oversight, there was no way to disable lossless mode
if it was previously enabled in a particular API instance.
jpeg_set_defaults() now accomplishes this, which makes
TJ*PARAM_LOSSLESS behave as intended/documented.
- Due to yet another oversight, setCompDefaults() in the TurboJPEG API
library permanently modified the value of TJ*PARAM_SUBSAMP when
generating a lossless JPEG image, which affected subsequent lossy
compression operations. This issue was hidden by the issue above and
thus does not need to be publicly documented.
Fixes#792
This is just a code readability thing. The logic effectively caused the
data precision to default to 8 if -precision was not specified, but that
was not obvious.
This commit also modifies tjcomptest so that it tests TJComp with no
-precision argument, to ensure that the data precision defaults to 8.
The target data precision isn't necessarily known at the time that the
calling program sets TJPARAM_LOSSLESSPT, so tj3Set() needs to allow all
possible values (from 0 to 15.) jpeg_enable_lossless(), which is called
within the body of tj3Compress*(), will throw an error if the point
transform value is greater than {data precision} - 1.
Since LLVM/Windows emulates Visual Studio, CMake sets
CMAKE_C_SIMULATE_ID="MSVC" but does not set MSVC. Thus, our build
system needs to enable most (but not all) of the Visual Studio features
when CMAKE_C_SIMLUATE_ID="MSVC". Support for LLVM/Windows is currently
undocumented because it isn't a standalone build environment. (It
requires the Visual Studio and Windows SDK headers and link libraries.)
Closes#786
This just improves code readability by emphasizing that we don't care
about the destination image's level of subsampling unless
TJPARAM_NOREALLOC is set or lossless cropping will be performed.
