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7b844bfd
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2023-07-28T11:46:10
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x86-64 SIMD: Use std stack frame/prologue/epilogue
This allows debuggers and profilers to reliably capture backtraces from
within the x86-64 SIMD functions.
In places where rbp was previously used to access temporary variables
(after stack alignment), we now use r15 and save/restore it accordingly.
The total amount of work is approximately the same, because the previous
code pushed the pre-alignment stack pointer to the aligned stack. The
new prologue and epilogue actually have fewer instructions.
Also note that the {un}collect_args macros now use rbp instead of rax to
access arguments passed on the stack, so we save a few instructions
there as well.
Based on:
https://github.com/alk/libjpeg-turbo/commit/debcc7c3b436467aea8d02c66a514c5099d0ad37
Closes #707
Closes #708
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bbedb4b5
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2019-11-05T15:43:21
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Merge branch 'master' into dev
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cf54623b
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2019-11-05T12:21:25
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Mac: Support hiding SIMD fct symbols w/ NASM 2.14+
(NASM 2.14+ now supports the private_extern section directive, which was
previously only available with YASM.)
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087c29e0
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2018-10-22T10:05:18
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Optimize Huffman encoding
This commit improves the C and SSE2 Huffman encoding implementations in
the following ways:
- Avoid using xmm8-xmm15 in the x86-64 SSE2 implementation. There is no
actual need to use those registers, and avoiding them produces a
cleaner WIN64 function entry/exit-- as well as shorter code, since REX
prefixes can be avoided (this is helpful on certain CPUs, such as
Intel Atom, for which instruction fetch and decoding can be a
bottleneck.)
- Optimize register usage so that fewer REX prefixes and
register-register moves are needed.
- Use the bit counter to store the number of free bits in the bit buffer
rather than the number of bits in the bit buffer. This changes the
method for inserting a code into the bit buffer to:
(put_buffer |= code << (free_bits -= code_size));
As a result:
* Only one bit counter needs to stay in a register (we just keep it in
cl.)
* The bit buffer contents are already properly aligned to be written
out (after a byte swap.)
* Adjusting the free bits counter and checking if the bit buffer is
full can be combined into a single operation.
* We can wait to flush the bit buffer until the buffer is actually
full and not just in danger of becoming full. Thus, eight bytes can
be flushed at a time.
- Speed is quite sensitive to the alignment of branch target labels, so
insert some padding and remove branches from the flush code.
(Flushing this way isn't actually faster when compared to using
branches, but the branchless code doesn't need extra alignment and is
thus smaller.)
- Speculatively write out the bit buffer as a single 8-byte write,
falling back to a byte-by-byte write only if there are any 0xFF bytes
in the bit buffer that need to be encoded as 0xFF 0x00.
- Use MMX registers for the 32-bit implementation (so the bit buffer can
be 64 bits wide.)
- Slightly reduce overall function code size.
- Eliminate or combine a few SSE instructions.
- Make some minor improvements to instruction scheduling.
- Adjust flush_bits() in jchuff.c to handle cases in which the bit
buffer has less than 7 free bits (apparently that couldn't happen
before.)
Based on:
https://github.com/1camper/libjpeg-turbo/commit/947a09defa2ec848322b1bae050d1b57b316a32a
https://github.com/1camper/libjpeg-turbo/commit/262ebb6b816fd8a49ff4d7185f6c5153dddde02f
https://github.com/1camper/libjpeg-turbo/commit/6e9a091221bb244c8ba232a942650e94254ffcf0
See change log for performance claims.
Closes #292
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95f4d6ef
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2019-10-24T02:13:23
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Merge branch 'master' into dev
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3a32d199
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2019-10-17T19:59:01
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x86 SIMD: Consistify capitalization of NASM types
byte, word, dword, qword, oword, and yword are all assembler keywords,
so it makes sense to use lowercase for these so as not to mistake them
for macros or constants.
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9a51a87a
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2019-10-17T11:21:32
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x86 SIMD: Remove obsolete [TAB8] comments
With apologies to Richard Hendricks, our assembly code no longer uses
tabs.
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133e4af0
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2018-09-04T16:56:22
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Add x32 ABI support on Linux
The x32 ABI is similar to the x86-64 ABI but uses 32-bit pointers.
(Refer to https://sites.google.com/site/x32abi)
Based on:
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/8da8fc5213d87336d6c7200aaeeca925603e12cf
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/1e33dfea8042230e266b453f53d69a6e37b7f0de
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/24ffea78da0f18d0d467d16e02dfb903e6c0181e
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/dedcf76753c8913ef5c3c6e4ea329d29494b6065
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/d04228a7b58b9aed5bcbec383630ec1a14a3c9ca
https://github.com/libjpeg-turbo/libjpeg-turbo/pull/274/commits/b4ad38316ae1899c8a00b6568bb0325d82edcd7a
Closes #274
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19c791cd
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2018-03-08T10:55:20
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Improve code formatting consistency
With rare exceptions ...
- Always separate line continuation characters by one space from
preceding code.
- Always use two-space indentation. Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
function name.
- Always precede pointer symbols ('*' and '**') by a space in type
casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
API libraries (using min() from tjutil.h is still necessary for
TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.
The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions. This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree. The
new convention is more consistent with the formatting of other OSS code
bases.
This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.
NOTES:
- Although it is no longer necessary for the function name in function
declarations to begin in Column 1 (this was historically necessary
because of the ansi2knr utility, which allowed libjpeg to be built
with non-ANSI compilers), we retain that formatting for the libjpeg
code because it improves readability when using libjpeg's function
attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
Uncrustify, although neither was completely up to the task, and thus
a great deal of manual tweaking was required. Note to developers of
code formatting utilities: the libjpeg-turbo code base is an
excellent test bed, because AFAICT, it breaks every single one of the
utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
formatted to match the SSE2 code (refer to
ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to
bother with this, but the Loongson MMI implementation demonstrated
that there is still academic value to the MMX implementation, as an
algorithmic model for other 64-bit vector implementations. Thus, it
is desirable to improve its readability in the same manner as that of
the SSE2 implementation.
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367a8386
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2018-02-26T19:41:59
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Make SIMD syms private for x86[-64]/Mach-O builds
... if building with YASM. NASM doesn't currently support the necessary
directives.
Closes #212
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7c2bfdb0
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2018-02-26T18:43:40
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Merge branch 'master' into dev
Closes #214
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88421563
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2018-02-23T21:56:32
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Make SIMD symbols private for x86[-64] ELF builds
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6abd3916
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2016-11-15T08:47:43
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Unified CMake-based build system
See #56 for discussion.
Fixes #21, Fixes #29, Fixes #37, Closes #56, Fixes #58, Closes #73
Obviates #82
See also:
https://sourceforge.net/p/libjpeg-turbo/feature-requests/5/
https://sourceforge.net/p/libjpeg-turbo/patches/5/
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