Implement TBB-based parallelism for C lib

1 files changed, 83 insertions, 1 deletions

diff --git a/c/CMakeLists.txt b/c/CMakeLists.txt
index 76c8947..ba88ed3 100644
--- a/c/CMakeLists.txt
+++ b/c/CMakeLists.txt
@@ -12,12 +12,20 @@ endif()
 project(libblake3
   VERSION 1.6.1
   DESCRIPTION "BLAKE3 C implementation"
-  LANGUAGES C ASM
+  LANGUAGES C CXX ASM
 )
 
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+
+option(BLAKE3_USE_TBB "Enable oneTBB parallelism" OFF)
+option(BLAKE3_FETCH_TBB "Allow fetching oneTBB from GitHub if not found on system" OFF)
+
+include(CTest)
 include(FeatureSummary)
 include(GNUInstallDirs)
 
+add_subdirectory(dependencies)
+
 # architecture lists for which to enable assembly / SIMD sources
 set(BLAKE3_AMD64_NAMES amd64 AMD64 x86_64)
 set(BLAKE3_X86_NAMES i686 x86 X86)
@@ -138,6 +146,11 @@ set_target_properties(blake3 PROPERTIES
   C_EXTENSIONS OFF
 )
 target_compile_features(blake3 PUBLIC c_std_99)
+if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.12)
+  target_compile_features(blake3 PUBLIC cxx_std_20)
+  # else: add it further below through `BLAKE3_CMAKE_CXXFLAGS_*`
+endif()
+
 # ensure C_EXTENSIONS OFF is respected without overriding CMAKE_C_STANDARD
 # which may be set by the user or toolchain file
 if (NOT POLICY CMP0128 AND NOT DEFINED CMAKE_C_STANDARD)
@@ -204,6 +217,67 @@ else()
   message(FATAL_ERROR "BLAKE3_SIMD_TYPE is set to an unknown value: '${BLAKE3_SIMD_TYPE}'")
 endif()
 
+if(BLAKE3_USE_TBB)
+  find_package(TBB 2021.11.0 QUIET)
+  if(NOT TBB_FOUND AND NOT TARGET TBB::tbb)
+    message(WARNING
+      "oneTBB not found; disabling BLAKE3_USE_TBB\n"
+      "Enable BLAKE3_FETCH_TBB to automatically fetch and build oneTBB"
+    )
+    set(BLAKE3_USE_TBB OFF)
+  else()
+    target_sources(blake3
+      PRIVATE
+        blake3_tbb.cpp)
+    target_link_libraries(blake3
+      PUBLIC
+        # Make shared TBB a transitive dependency. The consuming program is technically not required
+        # to link TBB in order for libblake3 to function but we do this in order to prevent the
+        # possibility of multiple separate TBB runtimes being linked into a final program in case
+        # the consuming program also happens to already use TBB.
+        TBB::tbb)
+    target_compile_definitions(blake3
+      PUBLIC
+        BLAKE3_USE_TBB)
+  endif()
+endif()
+
+if(BLAKE3_USE_TBB)
+  # Define some scratch variables for building appropriate flags per compiler
+  if(CMAKE_VERSION VERSION_LESS 3.12)
+    set(APPEND BLAKE3_CXX_STANDARD_FLAGS_GNU -std=c++20)
+    set(APPEND BLAKE3_CXX_STANDARD_FLAGS_MSVC /std:c++20)
+  endif()
+  set(BLAKE3_CXXFLAGS_GNU "-fno-exceptions;-fno-rtti;${BLAKE3_CXX_STANDARD_FLAGS_GNU}" CACHE STRING "C++ flags used for compiling private BLAKE3 library components with GNU-like compiler frontends.")
+  set(BLAKE3_CXXFLAGS_MSVC "/EHs-c-;/GR;${BLAKE3_CXX_STANDARD_FLAGS_MSVC}" CACHE STRING "C++ flags used for compiling private BLAKE3 library components with MSVC-like compiler frontends.")
+  # Get the C++ compiler name without extension
+  get_filename_component(BLAKE3_CMAKE_CXX_COMPILER_NAME "${CMAKE_CXX_COMPILER}" NAME_WE)
+  # Strip any trailing versioning from the C++ compiler name
+  string(REGEX MATCH "^(clang\\+\\+|clang-cl)" BLAKE3_CMAKE_CXX_COMPILER_NAME "${BLAKE3_CMAKE_CXX_COMPILER_NAME}")
+
+  # TODO: Simplify with CMAKE_CXX_COMPILER_FRONTEND_VARIANT once min CMake version is 3.14.
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+    target_compile_options(blake3 PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${BLAKE3_CXXFLAGS_GNU}>)
+  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    if(BLAKE3_CMAKE_CXX_COMPILER_NAME STREQUAL "clang++")
+      target_compile_options(blake3 PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${BLAKE3_CXXFLAGS_GNU}>)
+    elseif(BLAKE3_CMAKE_CXX_COMPILER_NAME STREQUAL "clang-cl")
+      target_compile_options(blake3 PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${BLAKE3_CXXFLAGS_MSVC}>)
+    endif()
+  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    target_compile_options(blake3 PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${BLAKE3_CXXFLAGS_GNU}>)
+  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    target_compile_options(blake3 PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${BLAKE3_CXXFLAGS_MSVC}>)
+  endif()
+
+  # Undefine scratch variables
+  unset(BLAKE3_CXX_STANDARD_FLAGS_GNU)
+  unset(BLAKE3_CXX_STANDARD_FLAGS_MSVC)
+  unset(BLAKE3_CMAKE_CXX_COMPILER_NAME)
+  unset(BLAKE3_CXXFLAGS_GNU)
+  unset(BLAKE3_CXXFLAGS_MSVC)
+endif()
+
 # cmake install support
 install(FILES blake3.h DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 install(TARGETS blake3 EXPORT blake3-targets
@@ -267,4 +341,12 @@ install(FILES "${CMAKE_BINARY_DIR}/libblake3.pc"
 add_feature_info("AMD64 assembly" BLAKE3_SIMD_AMD64_ASM "The library uses hand written amd64 SIMD assembly.")
 add_feature_info("x86 SIMD intrinsics" BLAKE3_SIMD_X86_INTRINSICS "The library uses x86 SIMD intrinsics.")
 add_feature_info("NEON SIMD intrinsics" BLAKE3_SIMD_NEON_INTRINSICS "The library uses NEON SIMD intrinsics.")
+add_feature_info("oneTBB parallelism" BLAKE3_USE_TBB "The library uses oneTBB parallelism.")
 feature_summary(WHAT ENABLED_FEATURES)
+
+if(BLAKE3_EXAMPLES)
+  include(BLAKE3/Examples)
+endif()
+if(BLAKE3_TESTING)
+  include(BLAKE3/Testing)
+endif()