ef9a4e05ba (libjpeg-turbo 1.4.x), which
was based on
https://bug815473.bmoattachments.org/attachment.cgi?id=692126
(https://bugzilla.mozilla.org/show_bug.cgi?id=815473), modified the C
baseline Huffman encoder so that it precomputes jpeg_nbits_table, in
order to facilitate sharing the table among multiple processes.
However, libjpeg-turbo never shared the table, and because the table was
implemented as a static array, f3a8684cd1
(libjpeg-turbo 1.5.x) and 37bae1a0e9
(libjpeg-turbo 2.0.x) each introduced a duplicate copy of the table for
(respectively) the SSE2 baseline Huffman encoder and the C progressive
Huffman encoder.
This commit does the following:
- Move the duplicated code in jchuff.c and jcphuff.c, originally
introduced in 0cfc4c17b7 and
37bae1a0e9, into a header
(jpeg_nbits.h).
- Credit the co-author of 0cfc4c17b7.
(Refer to https://sourceforge.net/p/libjpeg-turbo/patches/57).
- Modify the SSE2 baseline Huffman encoder so that the C Huffman
encoders can share its definition of jpeg_nbits_table.
- Move the definition of jpeg_nbits_table into a C source file
(jpeg_nbits.c) rather than a header, and define the table only if
USE_CLZ_INTRINSIC is undefined and the SSE2 baseline Huffman encoder
will not be built.
- Apply hidden symbol visibility to the shared definition of
jpeg_nbits_table, if the compiler supports the necessary attribute.
(In practice, only Visual C++ doesn't.)
Closes#114
See also:
https://bugzilla.mozilla.org/show_bug.cgi?id=1501523
The existing /*FALLTHROUGH*/ comments work with GCC but not Clang, so
this commit adds a FALLTHROUGH macro that uses the 'fallthrough'
attribute if the compiler supports it.
Refer to https://bugs.chromium.org/p/chromium/issues/detail?id=995993
NOTE: All versions of GCC that support -Wimplicit-fallthrough also
support the 'fallthrough' attribute, but certain other compilers (Oracle
Solaris Studio, for instance) support /*FALLTHROUGH*/ but not the
'fallthrough' attribute. Thus, this commit retains the /*FALLTHROUGH*/
comments, which have existed in the libjpeg code base in some form since
1994 (libjpeg v5.)
Closes#531
This commit adds C and SSE2 optimizations for the encode_mcu_AC_refine()
function used in progressive Huffman encoding.
The image used for testing can be retrieved from this page:
https://blog.cloudflare.com/doubling-the-speed-of-jpegtran
All timings done on `Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz`
clang version is `Apple LLVM version 9.0.0 (clang-900.0.39.2)`
gcc-5 version is `gcc-5 (Homebrew GCC 5.5.0) 5.5.0`
gcc-7 version is `gcc-7 (Homebrew GCC 7.2.0) 7.2.0`
Here are the results in comparison to libjpeg-turbo@3c54642 using
`time ./jpegtran -outfile /dev/null -progressive -optimise -copy none print_poster_0025.jpg`
C
clang x86_64: +7%
gcc-5 x86_64: +30%
gcc-7 x86_64: +33%
clang i386: +0%
gcc-5 i386: +24%
gcc-7 i386: +23%
SSE2
clang x86_64: +42%
gcc-5 x86_64: +53%
gcc-7 x86_64: +64%
clang i386: +35%
gcc-5 i386: +46%
gcc-7 i386: +49%
Discussion in libjpeg-turbo/libjpeg-turbo#46
Within the libjpeg API code, it seems to be more the convention than not
to separate the macro name and value by two or more spaces, which
improves general readability. Making this consistent across all of
libjpeg-turbo is less about my individual preferences and more about
making it easy to automatically detect variations from our chosen
formatting convention. I intend to release the script I'm using to
validate this stuff, once it matures and stabilizes a bit.
This is a subtle point, but AC_C_INLINE defines "inline" to be either
"inline", "__inline__", or "__inline". The subsequent test for
"inline __attribute__((always_inline))" uses this definition. The
attribute is irrespective of the inline keyword, so whereas
"__inline__ __attribute__((always_inline))" works under C89,
"inline __attribute__((always_inline))" doesn't, and defining INLINE to
the latter causes the build to fail. The easiest way around this is
simply to define "inline" ahead of "INLINE" in jconfigint.h,
which causes the inline keyword detected by AC_C_INLINE to modify the
INLINE macro if necessary.
Fix a regression introduced in 1.4.1 that prevented 32-bit and 64-bit
libjpeg-turbo RPMs from being installed simultaneously on recent Red
Hat/Fedora distributions. This was due to the addition of the
SIZEOF_SIZE_T macro in jconfig.h, which allows the Huffman codec to
determine the word size at compile time. Since that macro differs
between 32-bit and 64-bit builds, this caused a conflict between the
i386 and x86_64 RPMs (any differing files, other than executables, are
not allowed when 32-bit and 64-bit RPMs are installed simultaneously.)
Since the macro is used only internally, it has been moved into
jconfigint.h.
-- Auto-generates HAVE_LOCALE_H macro and adds it to jconfig.h (this is used by rdjpgcom.c.)
-- Reconciles the description and ordering of macros between config.h.in and jconfig.h.in, so the two files can be easily diffed.
-- Eliminates the use of the autoheader-generated config.h in the project and moves relevant internal-only macros into a new file, jconfigint.h. This is to avoid "already defined" warnings in files that were including both config.h (to get the internal autotools package information or the INLINE definition) and jconfig.h.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1258 632fc199-4ca6-4c93-a231-07263d6284db
