mirror of
https://github.com/nlohmann/json.git
synced 2026-09-24 06:10:22 +01:00
Niels Lohmann
71fe9f0b96
The benchmark project hasn't configured since #4793: download_test_data.cmake compiles cmake/detect_libcpp_version.cpp relative to CMAKE_SOURCE_DIR, which is tests/benchmarks when that is the top-level project, so try_run fails and so does `make run_benchmarks`. The path is now relative to the module itself, which is the same file for the main build. The Dump benchmark discarded dump()'s result, which is [[nodiscard]] by now; it warned, and left the optimizer free to shorten the loop. The result is now kept with benchmark::DoNotOptimize. A new cache variable, JSON_BENCHMARK_INCLUDE_DIR, names the directory holding the nlohmann/json.hpp to benchmark (single_include by default, as before), so the same benchmarks can be built against two versions and compared. tests/benchmarks/README.md documents what is measured, how to build and run the benchmarks, how to read the output, and how to compare two versions with Google Benchmark's compare.py; it recommends doing so by hand before a release rather than in CI. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
40 lines
1.5 KiB
CMake
40 lines
1.5 KiB
CMake
cmake_minimum_required(VERSION 3.11...3.14)
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project(JSON_Benchmarks LANGUAGES CXX)
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# set compiler flags
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if((CMAKE_CXX_COMPILER_ID MATCHES GNU) OR (CMAKE_CXX_COMPILER_ID MATCHES Clang))
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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -DNDEBUG -O3")
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endif()
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# configure Google Benchmarks
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include(FetchContent)
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FetchContent_Declare(
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benchmark
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GIT_REPOSITORY https://github.com/google/benchmark.git
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GIT_TAG origin/main
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GIT_SHALLOW TRUE
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)
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FetchContent_GetProperties(benchmark)
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if(NOT benchmark_POPULATED)
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FetchContent_Populate(benchmark)
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set(BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "" FORCE)
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add_subdirectory(${benchmark_SOURCE_DIR} ${benchmark_BINARY_DIR})
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endif()
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# download test data
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set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../cmake ${CMAKE_MODULE_PATH})
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include(download_test_data)
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# the header to benchmark; point this at a directory holding another version's
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# nlohmann/json.hpp to compare versions (see README.md)
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set(JSON_BENCHMARK_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../single_include" CACHE PATH
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"directory containing the nlohmann/json.hpp to benchmark")
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# benchmark binary
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add_executable(json_benchmarks src/benchmarks.cpp)
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target_compile_features(json_benchmarks PRIVATE cxx_std_11)
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target_link_libraries(json_benchmarks benchmark ${CMAKE_THREAD_LIBS_INIT})
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add_dependencies(json_benchmarks download_test_data)
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target_include_directories(json_benchmarks PRIVATE ${JSON_BENCHMARK_INCLUDE_DIR} ${CMAKE_BINARY_DIR}/include)
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