thodg/libgit2/deps/chromium-zlib/CMakeLists.txt

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• Hash : 83265b3e
  Author :
  Date : 2020-12-18T06:50:22
  

  zlib: Add support for building with Chromium's zlib implementation
  
  This change builds libgit2 using Chromium's zlib implementation by
  invoking cmake with `-DUSE_BUNDLED_ZLIB=ON -DUSE_CHROMIUM_ZLIB=ON`,
  which is ~10% faster than the bundled zlib for the core::zstream suite.
  
  This version of zlib has some optimizations:
  
  a) Decompression (Intel+ARM): inflate_fast, adler32, crc32, etc.
  b) Compression (Intel): fill_window, longest_match, hash function, etc.
  
  Due to the introduction of SIMD optimizations, and to get the maximum
  performance out of this fork of zlib, this requires an x86_64 processor
  with SSE4.2 and CLMUL (anything Westmere or later, ~2010). The Chromium
  zlib implementation also supports ARM with NEON, but it has not been
  enabled in this patch.
  
  Performance
  ===========
  
  TL;DR: Running just `./libgit2_clar -score::zstream` 100 times in a loop
  took 0:56.30 before and 0:50.67 after (~10% reduction!).
  
  The bundled and system zlib implementations on an Ubuntu Focal system
  perform relatively similar (the bundled one is marginally better due to
  the compiler being able to inline some functions), so only the bundled
  and Chromium zlibs were compared.
  
  For a more balanced comparison (to ensure that nothing regressed
  overall), `libgit2_clar` under `perf` was also run, and the zlib-related
  functions were compared.
  
  Bundled
  -------
  
  ```shell
  cmake \
    -DUSE_BUNDLED_ZLIB=ON \
    -DUSE_CHROMIUM_ZLIB=OFF \
    -DCMAKE_BUILD_TYPE="RelWithDebInfo" \
    -DCMAKE_C_FLAGS="-fPIC -fno-omit-frame-pointer" \
    -GNinja \
    ..
  ninja
  perf record --call-graph=dwarf ./libgit2_clar
  perf report --children
  ```
  
  ```
  Samples: 87K of event 'cycles', Event count (approx.): 75923450603
    Children      Self  Command       Shared Objec  Symbol
  +    4.14%     0.01%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output_chunk
  +    2.91%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output
  +    0.69%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output (inlined)
       0.17%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_init
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_reset
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_eos
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_done
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_free (inlined)
  
  Samples: 87K of event 'cycles', Event count (approx.): 75923450603
    Children      Self  Command       Shared Objec  Symbol
  +    3.12%     0.01%  libgit2_clar  libgit2_clar  [.] deflate
  +    2.65%     1.48%  libgit2_clar  libgit2_clar  [.] deflate_slow
  +    1.60%     0.55%  libgit2_clar  libgit2_clar  [.] inflate
  +    0.53%     0.00%  libgit2_clar  libgit2_clar  [.] write_deflate
       0.49%     0.36%  libgit2_clar  libgit2_clar  [.] inflate_fast
       0.46%     0.02%  libgit2_clar  libgit2_clar  [.] deflate_fast
       0.19%     0.19%  libgit2_clar  libgit2_clar  [.] inflate_table
       0.16%     0.01%  libgit2_clar  libgit2_clar  [.] inflateInit_
       0.15%     0.00%  libgit2_clar  libgit2_clar  [.] inflateInit2_ (inlined)
       0.10%     0.00%  libgit2_clar  libgit2_clar  [.] deflateInit_
       0.10%     0.00%  libgit2_clar  libgit2_clar  [.] deflateInit2_
       0.03%     0.00%  libgit2_clar  libgit2_clar  [.] deflateReset (inlined)
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] deflateReset
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] inflateEnd
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] deflateEnd
       0.01%     0.00%  libgit2_clar  libgit2_clar  [.] deflateResetKeep
       0.01%     0.01%  libgit2_clar  libgit2_clar  [.] inflateReset2
       0.01%     0.00%  libgit2_clar  libgit2_clar  [.] deflateReset (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateReset (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] deflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateResetKeep (inlined)
  ```
  
  Chromium
  --------
  
  ```shell
  cmake \
    -DUSE_BUNDLED_ZLIB=ON \
    -DUSE_CHROMIUM_ZLIB=ON \
    -DCMAKE_BUILD_TYPE="RelWithDebInfo" \
    -DCMAKE_C_FLAGS="-fPIC -fno-omit-frame-pointer" \
    -GNinja \
    ..
  ninja
  perf record --call-graph=dwarf ./libgit2_clar
  perf report --children
  ```
  
  ```
  Samples: 97K of event 'cycles', Event count (approx.): 80862210917
    Children      Self  Command       Shared Objec  Symbol
  +    3.31%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output_chunk
  +    2.27%     0.01%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output
  +    0.55%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_get_output (inlined)
       0.18%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_init
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_reset
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_free (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_done
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] git_zstream_free
  
  Samples: 97K of event 'cycles', Event count (approx.): 80862210917
    Children      Self  Command       Shared Objec  Symbol
  +    2.55%     0.01%  libgit2_clar  libgit2_clar  [.] deflate
  +    2.25%     1.41%  libgit2_clar  libgit2_clar  [.] deflate_slow
  +    1.10%     0.52%  libgit2_clar  libgit2_clar  [.] inflate
       0.36%     0.00%  libgit2_clar  libgit2_clar  [.] write_deflate
       0.30%     0.03%  libgit2_clar  libgit2_clar  [.] deflate_fast
       0.28%     0.15%  libgit2_clar  libgit2_clar  [.] inflate_fast_chunk_
       0.19%     0.19%  libgit2_clar  libgit2_clar  [.] inflate_table
       0.17%     0.01%  libgit2_clar  libgit2_clar  [.] inflateInit_
       0.16%     0.00%  libgit2_clar  libgit2_clar  [.] inflateInit2_ (inlined)
       0.15%     0.00%  libgit2_clar  libgit2_clar  [.] deflateInit_
       0.15%     0.00%  libgit2_clar  libgit2_clar  [.] deflateInit2_
       0.11%     0.01%  libgit2_clar  libgit2_clar  [.] adler32_z
       0.09%     0.09%  libgit2_clar  libgit2_clar  [.] adler32_simd_
       0.05%     0.00%  libgit2_clar  libgit2_clar  [.] deflateReset (inlined)
       0.05%     0.00%  libgit2_clar  libgit2_clar  [.] deflate_read_buf
       0.03%     0.00%  libgit2_clar  libgit2_clar  [.] inflateEnd
       0.02%     0.00%  libgit2_clar  libgit2_clar  [.] deflateReset
       0.01%     0.00%  libgit2_clar  libgit2_clar  [.] deflateEnd
       0.01%     0.01%  libgit2_clar  libgit2_clar  [.] inflateReset2
       0.01%     0.00%  libgit2_clar  libgit2_clar  [.] inflateReset (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] adler32
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateResetKeep (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] deflateResetKeep
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] inflateStateCheck (inlined)
       0.00%     0.00%  libgit2_clar  libgit2_clar  [.] deflateStateCheck (inlined)
  ```
  

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• deps/chromium-zlib/CMakeLists.txt

• # CMake build script for the bundled Chromium zlib implementation. So far, it
  # is only supported for x86_64 processors with CLMUL, SSE3, SSE4.2.
  #
  # TODO: The Chromium build file (in deps/chromium-zlib/zlib/BUILD.gn) supports
  # more platforms (like ARM with NEON), more can be enabled as needed.
  
  CMAKE_MINIMUM_REQUIRED(VERSION 3.11)
  
  include(FetchContent)
  include(FindGit)
  
  # Ensure that the git binary is present to download the sources.
  find_package(Git)
  IF(NOT Git_FOUND)
  	message(FATAL_ERROR "git is required to download the Chromium zlib sources")
  ENDIF()
  
  FetchContent_Populate(chromium_zlib_src
  	GIT_REPOSITORY https://chromium.googlesource.com/chromium/src/third_party/zlib.git
  	GIT_TAG 2c183c9f93a328bfb3121284da13cf89a0f7e64a
  	QUIET
  )
  
  # The Chromium build globally disables some warnings.
  disable_warnings(implicit-fallthrough)
  disable_warnings(unused-function)
  disable_warnings(unused-parameter)
  disable_warnings(sign-compare)
  disable_warnings(declaration-after-statement)
  disable_warnings(missing-declarations)
  
  # -O3 is also set by the Chromium configuration and has been deemed safe enough
  # for them.
  SET(CMAKE_C_FLAGS_RELWITHDEBINFO "-O3 -g -DNDEBUG")
  SET(CMAKE_C_FLAGS_RELEASE "-O3 -DNDEBUG")
  
  # Common definitions.
  add_definitions(
  	-DSTDC
  	-DNO_GZIP
  	-DZLIB_IMPLEMENTATION
  )
  list(APPEND SRC_ZLIB
  	"${chromium_zlib_src_SOURCE_DIR}/adler32.c"
  	"${chromium_zlib_src_SOURCE_DIR}/chromeconf.h"
  	"${chromium_zlib_src_SOURCE_DIR}/compress.c"
  	"${chromium_zlib_src_SOURCE_DIR}/contrib/optimizations/insert_string.h"
  	"${chromium_zlib_src_SOURCE_DIR}/cpu_features.c"
  	"${chromium_zlib_src_SOURCE_DIR}/cpu_features.h"
  	"${chromium_zlib_src_SOURCE_DIR}/crc32.c"
  	"${chromium_zlib_src_SOURCE_DIR}/crc32.h"
  	"${chromium_zlib_src_SOURCE_DIR}/deflate.c"
  	"${chromium_zlib_src_SOURCE_DIR}/deflate.h"
  	"${chromium_zlib_src_SOURCE_DIR}/gzclose.c"
  	"${chromium_zlib_src_SOURCE_DIR}/gzguts.h"
  	"${chromium_zlib_src_SOURCE_DIR}/gzlib.c"
  	"${chromium_zlib_src_SOURCE_DIR}/gzread.c"
  	"${chromium_zlib_src_SOURCE_DIR}/gzwrite.c"
  	"${chromium_zlib_src_SOURCE_DIR}/infback.c"
  	"${chromium_zlib_src_SOURCE_DIR}/inffast.c"
  	"${chromium_zlib_src_SOURCE_DIR}/inffast.h"
  	"${chromium_zlib_src_SOURCE_DIR}/inffixed.h"
  	"${chromium_zlib_src_SOURCE_DIR}/inflate.h"
  	"${chromium_zlib_src_SOURCE_DIR}/inftrees.c"
  	"${chromium_zlib_src_SOURCE_DIR}/inftrees.h"
  	"${chromium_zlib_src_SOURCE_DIR}/trees.c"
  	"${chromium_zlib_src_SOURCE_DIR}/trees.h"
  	"${chromium_zlib_src_SOURCE_DIR}/uncompr.c"
  	"${chromium_zlib_src_SOURCE_DIR}/zconf.h"
  	"${chromium_zlib_src_SOURCE_DIR}/zlib.h"
  	"${chromium_zlib_src_SOURCE_DIR}/zutil.c"
  	"${chromium_zlib_src_SOURCE_DIR}/zutil.h"
  )
  
  # x86_64-specific optimizations
  string(APPEND CMAKE_C_FLAGS " -mssse3 -msse4.2 -mpclmul")
  add_definitions(
    -DCHROMIUM_ZLIB_NO_CHROMECONF
  	-DX86_NOT_WINDOWS
  	-DADLER32_SIMD_SSSE3
  	-DCRC32_SIMD_SSE42_PCLMUL
  	-DDEFLATE_FILL_WINDOW_SSE2
  	-DINFLATE_CHUNK_READ_64LE
  	-DINFLATE_CHUNK_SIMD_SSE2
  )
  list(APPEND SRC_ZLIB
  	"${chromium_zlib_src_SOURCE_DIR}/adler32_simd.c"
  	"${chromium_zlib_src_SOURCE_DIR}/adler32_simd.h"
  	"${chromium_zlib_src_SOURCE_DIR}/contrib/optimizations/chunkcopy.h"
  	"${chromium_zlib_src_SOURCE_DIR}/contrib/optimizations/inffast_chunk.c"
  	"${chromium_zlib_src_SOURCE_DIR}/contrib/optimizations/inffast_chunk.h"
  	"${chromium_zlib_src_SOURCE_DIR}/contrib/optimizations/inflate.c"
  	"${chromium_zlib_src_SOURCE_DIR}/crc32_simd.c"
  	"${chromium_zlib_src_SOURCE_DIR}/crc32_simd.h"
  	"${chromium_zlib_src_SOURCE_DIR}/crc_folding.c"
  	"${chromium_zlib_src_SOURCE_DIR}/fill_window_sse.c"
  )
  
  list(SORT SRC_ZLIB)
  include_directories("${chromium_zlib_src_SOURCE_DIR}")
  add_library(chromium_zlib OBJECT ${SRC_ZLIB})
  

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