This adds 64-bit NEON coverage for all of the algorithms that are
covered by the 32-bit NEON implementation, except for h2v1 (4:2:2) fancy
upsampling (used when decompressing 4:2:2 JPEG images.) It also adds
64-bit NEON SIMD coverage for:
* slow integer forward DCT (compressor)
* h2v2 (4:2:0) downsampling (compressor)
* h2v1 (4:2:2) downsampling (compressor)
which are not covered in the 32-bit implementation.
Compression speedups relative to libjpeg-turbo 1.4.2:
Apple A7 (iPhone 5S), iOS, 64-bit: 113-150% (reported)
48-core ThunderX (RunAbove ARM Cloud), Linux, 64-bit: 2.1-33% (avg. 15%)
Refer to #44 and #49 for discussion
This commit also removes the unnecessary
if (simd_support & JSIMD_ARM_NEON)
statements from the jsimd* algorithm functions. Since the jsimd_can*()
functions check for the existence of NEON, the corresponding algorithm
functions will never be called if NEON isn't available.
Based on:
dcd9d84f10b0d87b811f70cd5c8a493e58d9a064837b19542f73dc43ccc8a82b71a261c1b1188c21305c89284e7f443f99954c2b53b77d
Unified version with fixes:
1004a3cd05
Full-color compression speedups relative to libjpeg-turbo 1.4.2:
800 MHz ARM Cortex-A9, iOS, 32-bit: 26-44% (avg. 32%)
Refer to #42 and #47 for discussion.
This commit also removes the unnecessary
if (simd_support & JSIMD_ARM_NEON)
statements from the jsimd* algorithm functions. Since the jsimd_can*()
functions check for the existence of NEON, the corresponding algorithm
functions will never be called if NEON isn't available. Removing those
if statements improved performance across the board by a couple of
percent.
Based on:
fc023c880c
Full-color compression speedups relative to libjpeg-turbo 1.4.2:
2.8 GHz Intel Xeon W3530, Linux, 64-bit: 2.2-18% (avg. 9.5%)
2.8 GHz Intel Xeon W3530, Linux, 32-bit: 10-25% (avg. 17%)
2.3 GHz AMD A10-4600M APU, Linux, 64-bit: 4.9-17% (avg. 11%)
2.3 GHz AMD A10-4600M APU, Linux, 32-bit: 8.8-19% (avg. 15%)
3.0 GHz Intel Core i7, OS X, 64-bit: 3.5-16% (avg. 10%)
3.0 GHz Intel Core i7, OS X, 32-bit: 4.8-14% (avg. 11%)
2.6 GHz AMD Athlon 64 X2 5050e:
Performance-neutral (give or take a few percent)
Full-color compression speedups relative to IPP:
2.8 GHz Intel Xeon W3530, Linux, 64-bit: 4.8-34% (avg. 19%)
2.8 GHz Intel Xeon W3530, Linux, 32-bit: -19%-7.0% (avg. -7.0%)
Refer to #42 for discussion. Numerous other approaches were attempted,
but this one proved to be the most performant across all platforms.
This commit also fixes#3 (works around, really-- the clang-compiled version
of jchuff.c still performs 20% worse than its GCC-compiled counterpart, but
that code is now bypassed by the new SSE2 Huffman algorithm.)
Based on:
2cb4d4133036c94e050d
Traditionally, the x86-64 code did not call init_simd() because it had
no need to (only SSE2 was supported.) However, having the ability to
disable SIMD at run time is a useful testing tool, and all of the other
SIMD implementations have this ability.
These days, INT32 is a commonly-defined datatype in system headers. We
cannot eliminate the definition of that datatype from jmorecfg.h, since
the INT32 typedef has technically been part of the libjpeg API since
version 5 (1994.) However, using INT32 internally is risky, because the
inclusion of a particular header (Xmd.h, for instance) could change the
definition of INT32 from long to int on 64-bit platforms and thus change
the internal behavior of libjpeg-turbo in unexpected ways (for instance,
failing to correctly set __INT32_IS_ACTUALLY_LONG to match the INT32
typedef-- perhaps as a result of including the wrong version of
jpeglib.h-- could cause libjpeg-turbo to produce incorrect results.)
The library has always been built in environments in which INT32 is
effectively long (on Windows, long is always 32-bit, so effectively it's
the same as int), so it makes sense to turn INT32 into an explicitly
long datatype. This ensures that libjpeg-turbo will always behave
consistently, regardless of the headers included at compile time.
Addresses a concern expressed in #26.
The IJG README file has been renamed to README.ijg, in order to avoid
confusion (many people were assuming that that was our project's README
file and weren't reading README-turbo.txt) and to lay the groundwork for
markdown versions of the libjpeg-turbo README and build instructions.
The DSPr2 code was errantly comparing the residual (t9, width & 0xF)
with the end pointer (t4, out + width) instead of the width directly
(a1). This would give the wrong results with any image whose output
width was less than 16. The other small changes (ulw to lw and removal
of the nop) are just some easy optimizations around this code.
This issue caused a buffer overrun and subsequent segfault on images
whose scaled output height was 1 pixel and whose scaled output width was
< 16 pixels. Note that the "plain" (non-fancy and non-merged) upsample
routine, which was affected by this bug, is normally not used except
when decompressing a non-YCbCr JPEG image, but it is also used when
decompressing a single-row image (because the other upsampling
algorithms require at least two rows.)
Closes#16.
(descriptions cribbed by DRC from discussion in #20)
In the x86-64 ABI, the high (unused) DWORD of a 32-bit argument's
register is undefined, so it was incorrect to use a 64-bit mov
instruction to transfer a JDIMENSION argument in the 64-bit SSE2 SIMD
functions. The code worked thus far only because the existing compiler
optimizers weren't smart enough to do anything else with the register in
question, so the upper 32 bits happened to be all zeroes-- for the past
6 years, on every x86-64 compiler previously known to mankind.
The bleeding-edge Clang/LLVM compiler has a smarter optimizer, and
under certain circumstances, it will attempt to load-combine adjacent
32-bit integers from one of the libjpeg structures into a single 64-bit
integer and pass that 64-bit integer as a 32-bit argument to one of the
SIMD functions (which is allowed by the ABI, since the upper 32 bits of
the 32-bit argument's register are undefined.) This caused the
libjpeg-turbo regression tests to crash.
Also enhance the documentation of JDIMENSION to explain that its size
is significant to the implementation of the SIMD code.
Closes#20. Refer also to http://crbug.com/532214.
When compiled with -mfpxx (which is now the default on Debian), there are
some restrictions on the use of odd-numbered FP registers. More details
about FPXX can be found here:
https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
This commit simply changes all uses of FP registers to an even-numbered
equivalent like this:
f0 -> f0
f1 -> f2
f2 -> f4
...
f8 -> f16
This commit should have no observable effect except that the MIPS assembly
will now compile with -mfpxx.
Closes#11
