kc3-lang/libjpeg-turbo/simd

simd

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Author Commit Date CI Message
DRC a30b3d28 2025-09-26T10:09:01 MMI: Format comments consistently with MMX code
DRC e0dcefd5 2025-09-25T18:13:10 Arm/x86: Allow JSIMD_NOHUFFENC to disable prog. Due to an oversight when the progressive Huffman encoding SIMD modules were developed, JSIMD_NOHUFFENC was not extended to those modules.
DRC 0c7698a0 2025-09-25T17:06:37 jfdctint-neon.c: Minor comment formatting tweaks
DRC c2f81b6d 2025-09-25T16:34:20 AltiVec: Fix -Wshadow warnings
DRC 7fbdfd60 2025-09-25T16:05:15 MMI: Fix some strict compiler warnings
DRC 5e27ca23 2025-09-19T14:21:49 x86: Reformat NASM code to improve readability (and simplify the checkstyle script)
DRC 42d2a243 2025-09-10T13:06:51 Build: Fix Loongson MMI detection with -Werror If compiler warnings are treated as errors, then the apostrophe in "Loongson MMI can't work with MIPS Release 6+" triggers a compiler warning that causes the HAVE_MMI test to fail. Surrounding the error message with quotes fixes the issue.
DRC 4e151a4a 2025-08-26T21:11:07 Remove vestigial filenames from SIMD code headers These were a relic of libjpeg/SIMD, which attempted to follow the conventions of the libjpeg source code, but they are no longer relevant (or even accurate in some cases.)
DRC 98c45838 2025-08-21T11:22:51 Fix issues with Windows Arm64EC builds Arm64EC basically wraps native Arm64 functions with an emulated Windows/x64 ABI, which can improve performance for Windows/x64 applications running under the x64 emulator on Windows/Arm. When building for Arm64EC, the compiler defines _M_X64 and _M_ARM64EC but not _M_ARM64.
DRC 602f0592 2024-12-12T00:09:34 AltiVec: Disable/Fix some strict compiler warnings 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__
DRC ea4ee229 2024-12-11T16:51:39 Neon: Disable some strict compiler warnings 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.
DRC 64567381 2024-08-31T17:31:02 Merge branch 'main' into dev
DRC eb753630 2024-08-31T16:50:08 Update URLs - Eliminate unnecessary "www." - Use HTTPS. - Update Java, MSYS, tdm-gcc, and NSIS URLs. - Update URL and title of Agner Fog's assembly language optimization manual. - Remove extraneous information about MASM and Borland Turbo Assembler and outdated NASM URLs from the x86 assembly headers, and mention Yasm.
DRC a27d9629 2024-07-04T10:05:50 Merge branch 'main' into dev
DRC e287a357 2024-07-04T10:03:50 Build: Put gastest.o in ${CMAKE_BINARY_DIR}/simd Closes #776
DRC 7e45654c 2024-03-04T18:10:16 Merge branch 'main' into dev
DRC 3202feb0 2024-02-29T16:10:20 x86-64 SIMD: Support CET if C compiler enables it - Detect at configure time, via the __CET__ C preprocessor macro, whether the C compiler will include either indirect branch tracking (IBT) or shadow stack support, and define a NASM macro (__CET__) if so. - Modify the x86-64 SIMD code so that it includes appropriate endbr64 instructions (to support IBT) and an appropriate .note.gnu.property section (to support both IBT and shadow stack) when __CET__ is defined. Closes #350
DRC 13355475 2024-02-29T12:18:49 x86 SIMD: Capitalize all instruction-like macros (to improve code readability)
DRC e69dd40c 2024-01-23T13:26:41 Reorganize source to make things easier to find - Move all libjpeg documentation, except for README.ijg, into the doc/ subdirectory. - Move the TurboJPEG C API documentation from doc/html/ into doc/turbojpeg/. - Move all C source code and headers into a src/ subdirectory. - Move turbojpeg-jni.c into the java/ subdirectory. Referring to #226, there is no ideal solution to this problem. A semantically ideal solution would have involved placing all source code, including the SIMD and Java source code, under src/ (or perhaps placing C library source code under lib/ and C test program source code under test/), all header files under include/, and all documentation under doc/. However: - To me it makes more sense to have separate top-level directories for each language, since the SIMD extensions and the Java API are technically optional features. src/ now contains only the code that is relevant to the core C API libraries and associated programs. - I didn't want to bury the java/ and simd/ directories or add a level of depth to them, since both directories already contain source code that is 3-4 levels deep. - I would prefer not to separate the header files from the C source code, because: 1. It would be disruptive. libjpeg and libjpeg-turbo have historically placed C source code and headers in the same directory, and people who are familiar with both projects (self included) are used to looking for the headers in the same directory as the C source code. 2. In terms of how the headers are used internally in libjpeg-turbo, the distinction between public and private headers is a bit fuzzy. - It didn't make sense to separate the test source code from the library source code, since there is not a clear distinction in some cases. (For instance, the IJG image I/O functions are used by cjpeg and djpeg as well as by the TurboJPEG API.) This solution is minimally disruptive, since it keeps all C source code and headers together and keeps java/ and simd/ as top-level directories. It is a bit awkward, because java/ and simd/ technically contain source code, even though they are not under src/. However, other solutions would have been more awkward for different reasons. Closes #226
DRC fa2b6ea0 2024-01-12T18:21:41 Eliminate duplicate copies of jpeg_nbits_table ef9a4e05ba919494cbebe50e15f332de5ab97e82 (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, f3a8684cd1c28e557d394470962a7a224c76ddbc (libjpeg-turbo 1.5.x) and 37bae1a0e977ee1ba769e6f0aa27e519ab6e58c6 (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 0cfc4c17b740cb2cbb11f9d85c8ab3745d5b913a and 37bae1a0e977ee1ba769e6f0aa27e519ab6e58c6, into a header (jpeg_nbits.h). - Credit the co-author of 0cfc4c17b740cb2cbb11f9d85c8ab3745d5b913a. (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
DRC 7b844bfd 2023-07-28T11:46:10 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
DRC 4e028ecd 2023-02-02T08:55:37 SIMD/x86: Initialize simd_support before every use As long as a libjpeg instance is only used by one thread at a time, a program is technically within its rights to call jpeg_start_*compress() in one thread and jpeg_(read|write)_*(), with the same libjpeg instance, in a second thread. However, because the various jsimd_can*() functions are called within the body of jpeg_start_*compress() and simd_support is now thread-local (due to f579cc11b33e5bfeb9931e37cc74b4a33c95d2e6), that led to a situation in which simd_support was initialized in the first thread but not the second. The uninitialized value of simd_support is 0xFFFFFFFF, which the second thread interpreted to mean that it could use any instruction set, and when it attempted to use AVX2 instructions on a CPU that didn't support them, an illegal instruction error occurred. This issue was known to affect libvips. This commit modifies the i386 and x86-64 SIMD dispatchers so that the various jsimd_*() functions always call init_simd(), if simd_support is uninitialized, prior to dispatching based on the value of simd_support. Note that the other SIMD dispatchers don't need this, because only the x86 SIMD extensions currently support multiple instruction sets. This patch has been verified to be performance-neutral to within +/- 0.4% with 32-bit and 64-bit code running on a 2.8 GHz Intel Xeon W3530 and a 3.6 GHz Intel Xeon W2123. Fixes #649
DRC 78a36f6d 2022-11-15T17:01:17 Fix buffer overrun in 12-bit prog Huffman encoder Regression introduced by 16bd984557fa2c490be0b9665e2ea0d4274528a8 and 5b177b3cab5cfb661256c1e74df160158ec6c34e The pre-computed absolute values used in encode_mcu_AC_first() and encode_mcu_AC_refine() were stored in a JCOEF (signed short) array. When attempting to losslessly transform a specially-crafted malformed 12-bit JPEG image with a coefficient value of -32768 into a progressive 12-bit JPEG image, the progressive Huffman encoder attempted to store the absolute value of -32768 in the JCOEF array, thus overflowing the 16-bit signed data type. Therefore, at this point in the code: https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L889 the absolute value was read as -32768, which caused the test at https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L896 to fail, falling through to https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L908 with an overly large value of r (46) that, when shifted left four places, incremented, and passed to emit_symbol(), exceeded the maximum index (255) for the derived code tables. Fortunately, the buffer overrun was fully contained within phuff_entropy_encoder, so the issue did not generate a segfault or other user-visible errant behavior, but it did cause a UBSan failure that was detected by OSS-Fuzz. This commit introduces an unsigned JCOEF (UJCOEF) data type and uses it to store the absolute values of DCT coefficients computed by the AC_first_prepare() and AC_refine_prepare() methods. Note that the changes to the Arm Neon progressive Huffman encoder extensions cause signed 16-bit instructions to be replaced with equivalent unsigned 16-bit instructions, so the changes should be performance-neutral. Based on: https://github.com/mayeut/libjpeg-turbo/commit/bbf61c0382c4f8bd1f1cfc666467581496c2fb7c Closes #628
DRC eb0a024a 2022-10-04T12:51:38 Remove redundant jconfigint.h #includes Because of 607b668ff96e40fdc749de9b1bb98e7f40c86d93, jconfigint.h is included by jinclude.h.
DRC f579cc11 2022-10-03T19:46:09 Make SIMD capability variables thread-local ... ... on platforms that support TLS, which should include all currently-supported platforms (https://libjpeg-turbo.org/Documentation/OfficialBinaries) Addresses a concern raised in #87 Although it is still my opinion that the data race in init_simd() was innocuous, we can now fix it for free thanks to ae87a958613b69628b92088b313ded0d4f59a716, so why not?
Donovan Watteau 59337a67 2022-07-06T12:11:50 PowerPC: Detect AltiVec support on OS X libjpeg-turbo's AltiVec SIMD extensions previously assumed that AltiVec instructions were available on all Power Macs that supported OS X 10.4 "Tiger" (the earliest version of OS X that libjpeg-turbo has ever supported), but Tiger can actually run on PowerPC G3 processors, which lack AltiVec instructions. This commit enables run-time detection of AltiVec instructions on OS X/PowerPC systems if AltiVec instructions are not force-enabled at compile time (using -maltivec). This allows the same build of libjpeg-turbo to support G3, G4, and G5 Power Macs. Closes #609
Jiaxun Yang fac83814 2022-05-14T14:34:43 Build: Don't enable Loongson MMI with MIPS R6+ MIPS R6 removed some instructions, so Loongson MMI cannot be built with MIPS R6+ toolchains. Closes #598
DRC 9abeff46 2022-03-09T11:48:30 Remove extraneous #include directives jinclude.h already includes stdio.h, stdlib.h, and string.h.
Jonathan Wright c5f269eb 2021-09-03T11:52:40 Neon/AArch64: Explicitly unroll quant loop w/Clang The loop in jsimd_quantize_neon() is only executed twice and should be unrolled for AArch64 targets. GCC does that by default, but Clang 11 and later versions available at the time of this writing do not. This patch adds an unroll pragma when targetting AArch64 with Clang. We do not use the unroll pragma for AArch32 targets, because it causes the Clang-generated assembly code to exhaust the available Neon registers (32 x 64-bit) and spill to the stack. (DRC: Referring to the discussion in #570, this is likely due to compiler confusion that results in poor register allocation. It is possible to eliminate the spillage and reduce the instruction count by loading the data on a just-in-time basis, thus explicitly interleaving compute and I/O, but the performance implications of that are currently unknown.) The effects of unrolling the quantization loop are: 1) elimination of the loop control flow overhead and 2) enabling the use of LDP/STP instructions that work from a single base pointer, instead of using double the number of LDR/STR instructions, each requiring an address calculation. Closes #570
DRC 98bc3eeb 2022-02-24T23:09:58 Neon/AArch64: Fix/suppress UBSan warnings - Suppress a UBSan warning regarding storing a 64-bit value to a non-64-bit-aligned address. That behavior is technically undefined per the C spec but is supported in the context of the AArch64 architecture and compilers. - Explicitly promote block_diff[i] to unsigned int prior to left shifting it, in order to avoid a UBSan warning. This warning also described behavior that is technically undefined per the C spec but is supported in the context of the AArch64 architecture and compilers. Changing the type cast order eliminated the warning without changing the generated assembly code. Closes #582
Jonathan Wright 147548c0 2021-09-06T11:31:37 Neon/AArch64: Accelerate Huffman encoding - Make better use of 128-bit vector registers, thus reducing the number of Neon instructions required to construct the AC coefficient bitmap. - Refactor the Neon computations of 'nbits' and 'diff' to use shorter and higher-throughput instruction sequences. DRC's notes: This commit partially integrates #570. Arm reported a 1-4% speedup on Cortex-A55 and Neoverse-N1 cores when using recent compilers but little or no speedup with Clang 10. I observed no speedup with Clang 10 on my Cortex-A53 and Cortex-A72 cores. Thus, referring to #582, the primary purpose of this commit is to fix UBSan warnings regarding the shift operations previously located at Line 253: https://github.com/libjpeg-turbo/libjpeg-turbo/blob/d640a457305164417a60f30c6457d316f0b44a9d/simd/arm/aarch64/jchuff-neon.c#L253
DRC 607b668f 2022-02-10T11:33:49 MSVC: Eliminate C4996 warnings in API libs The primary purpose of this is to encourage adoption of libjpeg-turbo in downstream Windows projects that forbid the use of "deprecated" functions. libjpeg-turbo's usage of those functions was not actually unsafe, because: - libjpeg-turbo always checks the return value of fopen() and ensures that a NULL filename can never be passed to it. - libjpeg-turbo always checks the return value of getenv() and never passes a NULL argument to it. - The sprintf() calls in format_message() (jerror.c) could never overflow the destination string buffer or leave it unterminated as long as the buffer was at least JMSG_LENGTH_MAX bytes in length, as instructed. (Regardless, this commit replaces those calls with snprintf() calls.) - libjpeg-turbo never uses sscanf() to read strings or multi-byte character arrays. - Because of b7d6e84d6a9283dc2bc50ef9fcaadc0cdeb25c9f, wrjpgcom explicitly checks the bounds of the source and destination strings before calling strcat() and strcpy(). - libjpeg-turbo always ensures that the destination string is terminated when using strncpy(). (548490fe5e2aa31cb00f6602d5a478b068b99682 made this explicit.) Regarding thread safety: Technically speaking, getenv() is not thread-safe, because the returned pointer may be invalidated if another thread sets the same environment variable between the time that the first thread calls getenv() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if: (1) A multithreaded calling application used the deprecated and undocumented TJFLAG_FORCEMMX/TJFLAG_FORCESSE/TJFLAG_FORCESSE2 flags in the TurboJPEG API or set one of the corresponding environment variables (which are only intended for testing purposes.) Since the TurboJPEG API library only ever passed string constants to putenv(), the only inherent risk (i.e. the only risk introduced by the library and not the calling application) was that the SIMD extensions may have read an incorrect value from one of the aforementioned environment variables. or (2) A multithreaded calling application modified the value of the JPEGMEM environment variable in one thread while another thread was reading the value of that environment variable (in the body of jpeg_create_compress() or jpeg_create_decompress().) Given that the libjpeg API provides a thread-safe way for applications to modify the default memory limit without using the JPEGMEM environment variable, direct modification of that environment variable by calling applications is not supported. Microsoft's implementation of getenv_s() does not claim to be thread-safe either, so this commit uses getenv_s() solely to mollify Visual Studio. New inline functions and macros (GETENV_S() and PUTENV_S) wrap getenv_s()/_putenv_s() when building for Visual Studio and getenv()/setenv() otherwise, but GETENV_S()/PUTENV_S() provide no advantages over getenv()/setenv() other than parameter validation. They are implemented solely for convenience. Technically speaking, strerror() is not thread-safe, because the returned pointer may be invalidated if another thread changes the locale and/or calls strerror() between the time that the first thread calls strerror() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if a multithreaded calling application encountered a file I/O error in tjLoadImage() or tjSaveImage(). Since both of those functions immediately copy the string returned from strerror() into a thread-local buffer, the risk is minimal, and the worst case would involve an incorrect error string being reported to the calling application. Regardless, this commit uses strerror_s() in the TurboJPEG API library when building for Visual Studio. Note that strerror_r() could have been used on Un*x systems, but it would have been necessary to handle both the POSIX and GNU implementations of that function and perform widespread compatibility testing. Such is left as an exercise for another day. Fixes #568
DRC 6d2d6d3b 2022-02-11T09:34:01 "YASM" = "Yasm" The assembler name was initially spelled "YASM", but it has been "Yasm" for the entirety of libjpeg-turbo's existence.
DRC e1588a2a 2022-02-10T22:23:26 Build: Fix Neon capability detection w/ MSVC (broken by 57ba02a408a9a55ccff25aae8b164632a3a4f177) Refer to #547
DRC a01857cf 2021-12-01T17:08:29 Build: Disallow NEON_INTRINSICS=0 if GAS is broken If NEON_INTRINSICS=0, then run the GAS sanity check from libjpeg-turbo 2.0.x and force-enable NEON_INTRINSICS if the test fails. This fixes the AArch32 build when using Clang 6.0 on Linux or the Clang toolchain in the Android NDK r15*-r16*. It also prevents users from manually disabling NEON_INTRINSICS if doing so would break the build (such as with Xcode 5.)
DRC 57ba02a4 2021-10-01T16:28:54 Build: Improve Neon capability detection - Use check_c_source_compiles() rather than check_symbol_exists() to detect the presence of vld1_s16_x3(), vld1_u16_x2(), and vld1q_u8_x4(). check_symbol_exists() is unreliable for detecting intrinsics, and in practice, it did not detect the presence of the aforementioned intrinsics in versions of GCC that support them. - Set DEFAULT_NEON_INTRINSICS=0 for GCC < 12, even if the aforementioned intrinsics are available. The AArch64 back end in GCC 10 and 11 supports the necessary intrinsics, but the GAS implementation is still faster when using those compilers. Fixes #547
Piotr Kubaj d401d625 2021-10-27T03:39:09 PowerPC: Detect AltiVec support on FreeBSD Recent FreeBSD/PowerPC compilers, such as Clang 11.0.x on FreeBSD 13, do the equivalent of passing -maltivec to the compiler by default, so run-time AltiVec detection is unnecessary. However, it becomes necessary when using other compilers or when passing -mno-altivec to the compiler. Closes #552
DRC a9c41fbc 2021-10-03T12:43:15 Build: Don't enable Neon SIMD exts with Armv6- When building for 32-bit Arm platforms, test whether basic Neon intrinsics will compile with the specified compiler and C flags. This prevents the build system from enabling the Neon SIMD extensions when targetting Armv6 and other legacy architectures that do not support Neon instructions. Regression introduced by bbd8089297862efb6c39a22b5623f04567ff6443. (Checking whether gas-preprocessor.pl was needed for 32-bit Arm builds had the effect of checking whether Neon instructions were supported.) Fixes #553
DRC 129f0cb7 2021-08-25T12:07:58 Neon/AArch64: Don't put GAS functions in .rodata Regression introduced by 240ba417aa4b3174850d05ea0d22dbe5f80553c1 Closes #546
DRC 2849d86a 2021-08-06T13:41:15 SSE2/64-bit: Fix trans. segfault w/ malformed JPEG Attempting to losslessly transform certain malformed JPEG images can cause the nbits table index in the Huffman encoder to exceed 32768, so we need to pad the SSE2 implementation of that table to 65536 entries as we do with the C implementation. Regression introduced by 087c29e07f7533ec82fd7eb1dafc84c29e7870ec Fixes #543
Peter Kasting b201838d 2021-07-10T16:07:05 Neon: Silence -Wimplicit-fallthrough warnings Refer to https://bugs.chromium.org/p/chromium/issues/detail?id=995993 Closes #534
DRC a1bfc058 2021-07-12T13:52:38 Neon/AArch32: Mark inline asm output as read/write 'buffer' is both passed into the inline assembly code and modified by it. See https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html, 6.47.2.3. With GCC 4, this commit does not change the generated assembly code at all. With GCC 8, this commit fixes an assembly error: /tmp/{foo}.s: Assembler messages: /tmp/{foo}.s:775: Error: registers may not be the same -- `str r9,[r9],#4' I'm not sure why that error went unnoticed, since I definitely benchmarked the previous commit with GCC 8. Anyhow, this commit changes the generated assembly code slightly but does not alter performance. With Clang 10, this commit changes the generated assembly code slightly but does not alter performance. Refer to #529
DRC 2a2970af 2021-07-09T15:35:56 Neon/AArch32: Work around Clang T32 miscompilation Referring to the C standard (http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf, J.2 Undefined behavior), the behavior of the compiler is undefined if "conversion between two pointer types produces a result that is incorrectly aligned." Thus, the behavior of this code *((uint32_t *)buffer) = BUILTIN_BSWAP32(put_buffer); in the AArch32 version of the FLUSH() macro is undefined unless 'buffer' is 32-bit-aligned. Referring to https://bugs.llvm.org/show_bug.cgi?id=50785, certain versions of Clang, when generating Thumb (T32) instructions, miscompile that code into an assembly instruction (stm) that requires the destination to be 32-bit-aligned. Since such alignment cannot be guaranteed within the Huffman encoder, this reportedly led to crashes (SIGBUS: illegal alignment) with AArch32/Thumb builds of libjpeg-turbo running on Android devices, although thus far I have been unable to reproduce those crashes with a plain Linux/Arm system. The miscompilation is visible with the Compiler Explorer: https://godbolt.org/z/rv1ccx1Pb However, it goes away when removing the return statement from the function. Thus, it seems that Clang's behavior in this regard is somewhat variable, which may explain why the crashes are only reproducible on certain platforms. The suggested workaround is to use memcpy(), but whereas Clang and recent GCC releases are smart enough to compile a 4-byte memcpy() call into a str instruction, GCC < 6 is not. Referring to https://godbolt.org/z/ae7Wje3P6, the only way to consistently produce the desired str instruction across all supported compilers is to use inline assembly. Visual C++ presumably does not miscompile the code in question, since no issues have been reported with it, but since the code relies on undefined compiler behavior, prudence dictates that e4ec23d7ae051c1c73947f889818900362fdc52d should be reverted for Visual C++, which this commit does. The performance impact of e4ec23d7ae051c1c73947f889818900362fdc52d for Visual C++/Arm builds is unknown (I have no ability to test such builds), but regardless, this commit reverts the Visual C++/Arm performance to that of libjpeg-turbo 2.1 beta1. Closes #529
DRC 0081c2de 2021-07-07T10:12:46 Neon/AArch32: Fix build if 'soft' float ABI used Arm compilers have three floating point ABI options: 'soft' compiles floating point operations as function calls into a software floating point library, which emulates floating point operations using integer operations. Floating point function arguments are passed using integer registers. 'softfp' also compiles floating point operations as function calls into a floating point library and passes floating point function arguments using integer registers, but the floating point library functions can use FPU instructions if the CPU supports them. 'hard' compiles floating point operations into inline FPU instructions, similarly to x86 and other architectures, and passes floating point function arguments using FPU registers. Not all AArch32 CPUs have FPUs or support Neon instructions, so on Linux and Android platforms, the AArch32 SIMD dispatcher in libjpeg-turbo only enables the Neon SIMD extensions at run time if /proc/cpuinfo indicates that the CPU supports Neon instructions or if Neon instructions are explicitly enabled (e.g. by passing -mfpu=neon to the compiler.) In order to support all AArch32 CPUs using the same code base, i.e. to support run-time FPU and Neon auto-detection, it is necessary to compile the scalar C source code using -mfloat-abi=soft. However, the 'soft' floating point ABI cannot be used when compiling Neon intrinsics, so the intrinsics implementation of the Neon SIMD extensions must be compiled using -mfloat-abi=softfp if the scalar C source code is compiled using -mfloat-abi=soft. This commit modifies the build system so that it detects whether -mfloat-abi=softfp must be explicitly added to the compiler flags when building the intrinsics implementation of the Neon SIMD extensions. This will be necessary if the build is using the 'soft' floating point ABI along with run-time auto-detection of Neon instructions. Fixes #523
Jonathan Wright e4ec23d7 2021-02-10T16:45:50 Neon: Use byte-swap builtins instead of inline asm Define compiler-independent byte-swap macros and use them instead of executing 'rev' via inline assembly code with GCC-compatible compilers or a slow shift-store sequence with Visual C++. * This produces identical assembly code with: - 64-bit GCC 8.4.0 (Linux) - 64-bit GCC 9.3.0 (Linux) - 64-bit Clang 10.0.0 (Linux) - 64-bit Clang 10.0.0 (MinGW) - 64-bit Clang 12.0.0 (Xcode 12.2, macOS) - 64-bit Clang 12.0.0 (Xcode 12.2, iOS) * This produces different assembly code with: - 64-bit GCC 4.9.1 (Linux) - 32-bit GCC 4.8.2 (Linux) - 32-bit GCC 8.4.0 (Linux) - 32-bit GCC 9.3.0 (Linux) Since the intrinsics implementation of Huffman encoding is not used by default with these compilers, this is not a concern. - 32-bit Clang 10.0.0 (Linux) Verified performance neutrality Closes #507
DRC e795afc3 2021-03-25T22:36:15 SSE2: Fix prog Huff enc err if Sl%32==0 && Al!=0 (regression introduced by 16bd984557fa2c490be0b9665e2ea0d4274528a8) This implements the same fix for jsimd_encode_mcu_AC_refine_prepare_sse2() that a81a8c137b3f1c65082aa61f236aa88af61b3ad4 implemented for jsimd_encode_mcu_AC_first_prepare_sse2(). Based on: https://github.com/MegaByte/libjpeg-turbo/commit/1a59587397150c9ef9dffc5813cb3891db4bc0c8 https://github.com/MegaByte/libjpeg-turbo/commit/eb176a91d87a470bf8c987be786668aa944dd1dd Fixes #509 Closes #510
Adrian Bunk 2c01200c 2021-03-15T19:56:53 Build: Fix incorrect regexes w/ if(...MATCHES...) "arm*" as a regex means 'ar' followed by zero or more 'm' characters, which matches 'parisc' and 'sparc64' as well.
Richard Townsend 74e6ea45 2021-01-05T20:23:11 Neon: Fix Huffman enc. error w/Visual Studio+Clang The GNU builtin function __builtin_clzl() accepts an unsigned long argument, which is 8 bytes wide on LP64 systems (most Un*x systems, including Mac) but 4 bytes wide on LLP64 systems (Windows.) This caused the Neon intrinsics implementation of Huffman encoding to produce mathematically incorrect results when compiled using Visual Studio with Clang. This commit changes all invocations of __builtin_clzl() in the Neon SIMD extensions to __builtin_clzll(), which accepts an unsigned long long argument that is guaranteed to be 8 bytes wide on all systems. Fixes #480 Closes #490
Jonathan Wright eb14189c 2020-11-17T12:48:49 Fix Neon SIMD build issues with Visual Studio - Use the _M_ARM and _M_ARM64 macros provided by Visual Studio for compile-time detection of Arm builds, since __arm__ and __aarch64__ are only present in GNU-compatible compilers. - Neon/intrinsics: Use the _CountLeadingZeros() and _CountLeadingZeros64() intrinsics provided by Visual Studio, since __builtin_clz() and __builtin_clzl() are only present in GNU-compatible compilers. - Neon/intrinsics: Since Visual Studio does not support static vector initialization, replace static initialization of Neon vectors with the appropriate intrinsics. Compared to the static initialization approach, this produces identical assembly code with both GCC and Clang. - Neon/intrinsics: Since Visual Studio does not support inline assembly code, provide alternative code paths for Visual Studio whenever inline assembly is used. - Build: Set FLOATTEST appropriately for AArch64 Visual Studio builds (Visual Studio does not emit fused multiply-add [FMA] instructions by default for such builds.) - Neon/intrinsics: Move temporary buffer allocation outside of nested loops. Since Visual Studio configures Arm builds with a relatively small amount of stack memory, attempting to allocate those buffers within the inner loops caused a stack overflow. Closes #461 Closes #475
DRC 33859880 2020-11-13T12:12:47 Neon: Auto-detect compiler intrinsics completeness This allows the Neon intrinsics code to be built successfully (albeit likely with reduced run-time performance) with Xcode 5.0-6.2 (iOS/AArch64) and Android NDK < r19 (AArch32). Note that Xcode 5.0-6.2 will not build the Armv8 GAS code without gas-preprocessor.pl, and no version of Xcode will build the Armv7 GAS code without gas-preprocessor.pl, so we always use the full Neon intrinsics implementation by default with macOS and iOS builds. Auto-detecting the completeness of the compiler's set of Neon intrinsics also allows us to more intelligently set the default value of NEON_INTRINSICS, based on the values of HAVE_VLD1*. This is a reasonable, albeit imperfect, proxy for whether a compiler has a full and optimal set of Neon intrinsics. Specific notes: - 64-bit RGB-to-YCbCr color conversion does not use any of the intrinsics in question, regresses with GCC - 64-bit accurate integer forward DCT uses vld1_s16_x3(), regresses with GCC - 64-bit Huffman encoding uses vld1q_u8_x4(), regresses with GCC - 64-bit YCbCr-to-RGB color conversion does not use any of the intrinsics in question, regresses with GCC - 64-bit accurate integer inverse DCT uses vld1_s16_x3(), regresses with GCC - 64-bit 4x4 inverse DCT uses vld1_s16_x3(). I did not test this algorithm in isolation, so it may in fact regress with GCC, but the regression may be hidden by the speedup from the new SIMD-accelerated upsampling algorithms. - 32-bit RGB-to-YCbCr color conversion: uses vld1_u16_x2(), regresses with GCC - 32-bit accurate integer forward DCT uses vld1_s16_x3(), regression irrelevant because there was no previous implementation - 32-bit accurate integer inverse DCT uses vld1_s16_x3(), regresses with GCC - 32-bit fast integer inverse DCT does not use any of the intrinsics in question, regresses with GCC - 32-bit 4x4 inverse DCT uses vld1_s16_x3(). I did not test this algorithm in isolation, so it may in fact regress with GCC, but the regression may be hidden by the speedup from the new SIMD-accelerated upsampling algorithms. Presumably when GCC includes a full and optimal set of Neon intrinsics, the HAVE_VLD1* tests will pass, and the full Neon intrinsics implementation will be enabled automatically.
DRC bbd80892 2020-11-10T17:54:14 Neon: Finalize intrinsics implementation - Remove gas-preprocessor.pl. None of the compilers that can build the new intrinsics implementation require gas-preprocessor.pl (tested with Xcode and with Clang 3.9+ for Linux.) - Document that Xcode 6.3.x or later is now required for iOS builds (older versions of Xcode do not have a full set of Neon intrinsics.) - Add a change log entry. - Do not enable the ASM CMake language unless NEON_INTRINSICS is false. - Add a Clang/Arm64 test to .travis.yml in order to test the new intrinsics implementation. Closes #455
Martyn Jacques 141f26ff 2018-09-18T18:28:31 Neon: Intrinsics impl. of 2x2 and 4x4 scaled IDCTs The previous AArch32 and AArch64 GAS implementations have been removed, since the intrinsics implementations provide the same or better performance.
Jonathan Wright 4574f01f 2018-06-28T16:17:36 Neon: Intrinsics impl. of h2v1 & h2v2 plain upsamp There was no previous GAS implementation. NOTE: This doesn't produce much of a speedup when using -O3, because -O3 already enables Neon autovectorization, which works well for the scalar C implementation of plain upsampling. However, the Neon SIMD implementation will benefit other optimization levels.
Jonathan Wright ba52a3de 2018-07-19T18:46:24 Neon: Intrinsics impl of h2v1 & h2v2 merged upsamp There was no previous GAS implementation. This commit also reverts 40557b23015d2f8b576420231b8dd1f39f2ceed8 and 7723d7f7d0aa40349d5bdd1fbe4f8631fd5a2b57. 7723d7f7d0aa40349d5bdd1fbe4f8631fd5a2b57 was only necessary because there was no Neon implementation of merged upsampling/color conversion, and 40557b23015d2f8b576420231b8dd1f39f2ceed8 was only necessary because of 7723d7f7d0aa40349d5bdd1fbe4f8631fd5a2b57.
Jonathan Wright 240ba417 2020-01-07T16:40:32 Neon: Intrinsics impl. of prog. Huffman encoding The previous AArch64 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance. There was no previous AArch32 GAS implementation.
Jonathan Wright ed581cd9 2019-06-12T18:16:53 Neon: Intrinsics impl. of accurate int inverse DCT The previous AArch32 and AArch64 GAS implementations are retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable.
Jonathan Wright 2c6b68e2 2018-09-25T18:20:25 Neon: Intrinsics impl. of fast integer Inverse DCT The previous AArch32 GAS implementation is retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable. The previous AArch64 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright 2acfb93c 2019-05-08T15:43:26 Neon: Intrinsics impl. of h1v2 fancy upsamling There was no previous GAS implementation.
Jonathan Wright 97530777 2018-06-15T11:13:52 Neon: Intrinsics impl. of h2v1 & h2v2 fancy upsamp The previous AArch32 GAS implementation of h2v1 fancy upsampling has been removed, since the intrinsics implementation provides the same or better performance. There was no previous GAS implementation of h2v2 fancy upsampling, and there was no previous AArch64 GAS implementation of h2v1 fancy upsampling.
Jonathan Wright 5dbd3932 2018-08-01T16:52:31 Neon: Intrinsics implementation of YCbCr->RGB565 The previous AArch64 GAS implementation is retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable. The previous AArch32 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright 0f35cd68 2018-07-16T10:25:14 Neon: Intrinsics implementation of YCbCr->RGB The previous AArch64 GAS implementation is retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable. The previous AArch32 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright f3c3f01d 2018-09-24T04:35:20 Neon: Intrinsics impl. of Huffman encoding The previous AArch64 GAS implementation is retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable. The previous AArch32 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright d0004de5 2018-08-22T13:38:37 Neon: Intrinsics impl. of accurate int forward DCT The previous AArch64 GAS implementation is retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using the new NEON_INTRINSICS CMake variable. There was no previous AArch32 GAS implementation.
Jonathan Wright 3d84668d 2018-08-23T14:22:23 Neon: Intrinsics impl. of fast integer forward DCT The previous AArch32 and AArch64 GAS implementations have been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright 951d3677 2018-08-24T18:04:21 Neon: Intrinsics impl. of int sample conv./quant. The previous AArch32 and AArch64 GAS implementations have been removed, since the intrinsics implementation provides the same or better performance.
Jonathan Wright 366168aa 2018-08-06T15:14:34 Neon: Intrinsics impl. of h2v1 & h2v2 downsampling The previous AArch64 GAS implementation has been removed, since the intrinsics implementation provides the same or better performance. There was no previous AArch32 GAS implementation.
Jonathan Wright f73b1dbc 2018-08-09T15:08:21 Neon: Intrinsics implementation of RGB->Grayscale There was no previous GAS implementation.
Jonathan Wright 4f2216b4 2019-11-26T18:14:33 Neon: Intrinsics implementation of RGB->YCbCr The previous AArch32 and AArch64 GAS implementations are retained by default when using GCC, in order to avoid a performance regression. The intrinsics implementation can be forced on or off using a new NEON_INTRINSICS CMake variable.
DRC 7c1a1789 2020-11-05T16:04:55 Merge branch 'master' into dev
DRC 6e632af9 2020-11-04T10:13:06 Demote "fast" [I]DCT algorithms to legacy status - Refer to the "slow" [I]DCT algorithms as "accurate" instead, since they are not slow under libjpeg-turbo. - Adjust documentation claims to reflect the fact that the "slow" and "fast" algorithms produce about the same performance on AVX2-equipped CPUs (because of the dual-lane nature of AVX2, it was not possible to accelerate the "fast" algorithm beyond what was achievable with SSE2.) Also adjust the claims to reflect the fact that the "fast" algorithm tends to be ~5-15% faster than the "slow" algorithm on non-AVX2-equipped CPUs, regardless of the use of the libjpeg-turbo SIMD extensions. - Indicate the legacy status of the "fast" and float algorithms in the documentation and cjpeg/djpeg usage info. - Remove obsolete paragraph in the djpeg man page that suggested that the float algorithm could be faster than the "fast" algorithm on some CPUs.
DRC cd342acf 2020-10-27T16:42:14 Merge branch 'master' into dev
DRC d27b935a 2020-10-27T15:04:39 Consistify formatting to simplify checkstyle The checkstyle script was hastily developed prior to libjpeg-turbo 2.0 beta1, so it has a lot of exceptions and is thus prone to false negatives. This commit eliminates some of those exceptions.
DRC 59352195 2020-10-19T21:17:46 Merge branch 'master' into dev
DRC 1ed312ea 2020-10-15T17:47:31 "ARM"="Arm", "NEON"="Neon" Refer to: https://www.arm.com/company/policies/trademarks/arm-trademark-list/arm-trademark https://www.arm.com/company/policies/trademarks/arm-trademark-list/neon-trademark NOTE: These changes are only applied to change log entries for 2.0.x and later, since the change log is a historical record and Arm's new trademark policy did not go into effect until late 2017.
DRC ae08115d 2020-10-15T10:25:46 Merge branch 'master' into dev
DRC b5a14727 2020-10-15T10:22:51 Build: Fix permissions
DRC 6ab61fa1 2020-09-13T17:02:09 Merge branch 'master' into dev
DRC 6ee5d5f5 2020-07-28T18:06:20 ARMv8 NEON: Support Windows builds w/AArch64 MinGW Based on: https://github.com/mstorsjo/libjpeg-turbo/commit/c5ef6659285a7d5bc74c679aa87ad187186cf7e1 Closes #438
DRC 00d48d7e 2020-02-17T18:14:10 Merge branch 'master' into dev
DRC 035262a1 2020-02-17T18:03:10 MIPS DSPr2: Work around various 'make test' errors Referring to #408, this commit #ifdefs DSPr2 SIMD functions that only work on little endian processors, and it completely excludes jsimd_h2v1_downsample_dspr2() and jsimd_h2v2_downsample_dspr2(). The latter two functions fail with the TJBench tiling regression tests, most likely because the implementation of the functions predates those tests.
DRC ed7cab47 2020-02-17T16:35:00 MIPS DSPr2: Fix compiler warning with -mdspr2 If -mdspr2 is passed to the compiler, __mips_dsp will be defined, and __mips_dsp_rev will be >= 2, so parse_proc_cpuinfo() will not be used.
DRC 42d679b9 2020-02-17T15:19:32 MIPS SIMD: Always honor JSIMD_FORCE* env vars Previously, these environment variables were not honored unless a 74K CPU was detected, but this detection doesn't work properly with QEMU's user mode emulation. With all other CPU types, libjpeg-turbo honors JSIMD_FORCE* regardless of CPU detection.
DRC b34c85ea 2019-12-31T01:20:12 Merge branch 'master' into dev
DRC 166e3421 2019-12-31T01:10:30 simd/arm64/jsimd_neon.S: Fix checkstyle issue
DRC c4675d62 2019-12-31T00:42:53 Merge branch 'master' into dev
DRC b542e4c8 2019-12-20T13:18:23 ARMv8 SIMD: Support execute-only memory (XOM) Move constants out of the .text section in simd/arm64/jsimd_neon.S and into a .rodata section. This ensures that the ARMv8 NEON SIMD extensions are compatible with memory layouts that are marked execute-only (and thus unreadable.) Based on: https://github.com/ivanloz/libjpeg-turbo/commit/88f3ca7664fadfb5e106efecb7845753aaf330b7 Closes #318
DRC 81b8c0ee 2019-12-17T14:18:35 Loongson MMI: Merge with MIPS64/add auto-detection Modern Loongson processors are MIPS64-compatible, and MMI instructions are now supported in the mainline of GCC. Thus, this commit adds compile-time and run-time auto-detection of MMI instructions and moves the MMI SIMD extensions for libjpeg-turbo from simd/loongson/ to simd/mips64/. That will allow MMI and MSA instructions to co-exist in the same build once #377 has been integrated. Based on: https://github.com/FlyGoat/libjpeg-turbo/commit/82953ddd61549428f58066f7eff0d60ce7429865 Closes #383
mayeut e821464f 2018-04-03T12:47:54 ARM64 NEON SIMD impl. of prog. Huffman encoding This commit adds ARM64 NEON optimizations for the encode_mcu_AC_first() and encode_mcu_AC_refine() functions used in progressive Huffman encoding. Compression speedups for the typical set of five libjpeg-turbo test images (https://libjpeg-turbo.org/About/Performance): Cortex-A53: 23.8-39.2% (avg. 32.2%) Cortex-A72: 26.8-41.1% (avg. 33.5%) Apple A7: 29.7-45.9% (avg. 39.6%) Closes #229
DRC 9c6f79e9 2019-11-13T14:36:37 Fix formatting issues detected by checkstyle
DRC f60b6dd3 2019-11-12T17:42:39 Remove vestigial jpeg_nbits_table.inc Not needed since 087c29e07f7533ec82fd7eb1dafc84c29e7870ec
DRC 713c451f 2019-11-08T14:53:55 Enable SSE2 progressive Huffman encoder for x32 Referring to #289, I'm not sure where I arrived at the conclusion that the SSE2 progressive Huffman encoder doesn't provide any speedup for x32. Upon re-testing, I discovered it to be about 50% faster than the C encoder. This commit also re-purposes one of the CI tests (specifically, the jpeg-7 API/ABI test) so that it tests x32 as well.
DRC cbf0fcc8 2019-11-05T11:56:06 i386 SSE2 Huffman: Fix pointer arithmetic issue Splitting the pointer arithmetic in GET_SYM() into a separate add and sub instruction was an attempt to work around an error ("invalid operand type") that occurred when assembling the file with NASM. However, this created a link error on macOS ("ld: illegal text-relocation to '_jconst_huff_encode_one_block' in simd/CMakeFiles/simd.dir/i386/jchuff-sse2.asm.o from '_jsimd_huff_encode_one_block_sse2' in simd/CMakeFiles/simd.dir/i386/jchuff-sse2.asm.o for architecture i386") and also changed the alignment of the code in ways that might have affected the previous benchmark results (which took a great deal of time to obtain.) Ultimately, the path of least resistance is just to require NASM 2.13 or later.
DRC bbedb4b5 2019-11-05T15:43:21 Merge branch 'master' into dev
DRC cf54623b 2019-11-05T12:21:25 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.)
DRC 087c29e0 2018-10-22T10:05:18 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
DRC d92ae5df 2019-11-04T18:50:45 Merge branch 'master' into dev
DRC 6902cdb1 2019-10-28T14:28:29 Build: Don't require ASM_NASM if !REQUIRE_SIMD The build system is supposed to fall back to a non-SIMD build if WITH_SIMD==1 but REQUIRE_SIMD==0. Based on: https://github.com/emlix/libjpeg-turbo/commit/972df912d08b755db3ca60d93b058a42e97a79eb Closes #384
DRC 95f4d6ef 2019-10-24T02:13:23 Merge branch 'master' into dev
DRC 3a32d199 2019-10-17T19:59:01 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.
DRC 9a51a87a 2019-10-17T11:21:32 x86 SIMD: Remove obsolete [TAB8] comments With apologies to Richard Hendricks, our assembly code no longer uses tabs.
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