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Merge pull request InsightSoftwareConsortium#6004 from hjmjohnson/fftw-compute-optimized-defaults
PERF: Enable FFTW SIMD codelets with per-CPU introspection at configure time
2 parents 6dcda76 + 418a2c2 commit a43fa81

1 file changed

Lines changed: 81 additions & 19 deletions

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‎CMake/itkExternal_FFTW.cmake‎

Lines changed: 81 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -1,19 +1,30 @@
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#
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# Encapsulates building FFTW as an External Project.
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#
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# NOTE: internal building of fftw is for convenience,
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# and the version of fftw built here does not
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# use modern hardware optimzations.
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# SIMD codelet selection
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# ----------------------
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# FFTW SIMD codelets are hand-written assembly routines baked into the
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# library at compile time. Passing -march=native to the ITK build does
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# NOT activate them; they must be requested explicitly via FFTW's own
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# CMake options (ENABLE_NEON, ENABLE_SSE, ENABLE_SSE2, ENABLE_AVX, ENABLE_AVX2).
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#
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# The build configuration chosen to be
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# generalizable to as many hardware platforms.
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# Being backward compatible for decades
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# old hardware is the goal of this internal
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# representation.
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# This file detects appropriate defaults at cmake configure time:
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#
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# This is primarily used to support testing
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# and should not be used for production
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# builds where performance is a concern.
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# Native builds (CMAKE_CROSSCOMPILING is false):
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# - ARM64 (aarch64/arm64): NEON=ON (mandatory in ARMv8); x86 SIMD off.
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# - x86/x86_64: each of SSE, SSE2, AVX, AVX2 is probed individually
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# via __builtin_cpu_supports() / CheckCSourceRuns so that the
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# detected flags match the actual build-host CPU. A pre-AVX
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# Sandy Bridge gets SSE+SSE2 only; a Haswell or later gets all four.
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# - Other architectures: all SIMD off (conservative fallback).
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#
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# Cross-compiled builds (CMAKE_CROSSCOMPILING is true):
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# - ARM64: NEON=ON (mandatory); x86 SIMD off.
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# - x86_64: SSE+SSE2 only (baseline; AVX/AVX2 not assumed for target).
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# - Other: all SIMD off.
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#
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# Every flag is an individually overridable cache option, e.g.:
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# cmake -DFFTW_ENABLE_AVX2=OFF ...
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#
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# These instructions follow the guidance provided for modern cmake usage as described:
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# https://github.com/dev-cafe/cmake-cookbook/blob/master/chapter-08/recipe-03/c-example/external/upstream/fftw3/CMakeLists.txt
@@ -53,6 +64,55 @@ if(NOT ITK_USE_SYSTEM_FFTW)
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set(_fftw_url "https://data.kitware.com/api/v1/file/hashsum/sha512/${_fftw_url_hash}/download")
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set(FFTW_STAGED_INSTALL_PREFIX "${ITK_BINARY_DIR}/fftw")
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# Detect SIMD defaults (see file header for full policy description).
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# CheckCSourceRuns results are cached after the first cmake configure run.
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include(CheckCSourceRuns)
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set(_fftw_default_neon OFF)
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set(_fftw_default_sse OFF)
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set(_fftw_default_sse2 OFF)
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set(_fftw_default_avx OFF)
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set(_fftw_default_avx2 OFF)
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if(NOT CMAKE_CROSSCOMPILING)
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if(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|arm64|ARM64")
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# NEON is mandatory in ARMv8/AArch64 — every arm64 CPU has it.
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set(_fftw_default_neon ON)
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elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64|i686")
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# Probe each x86 SIMD level individually via CPUID so the defaults
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# are accurate for the actual build-host CPU (e.g. pre-AVX Sandy Bridge
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# or pre-AVX2 Ivy Bridge get only the levels their hardware supports).
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# __builtin_cpu_supports is a GCC/Clang intrinsic; skip on MSVC.
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if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang|AppleClang")
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foreach(_fftw_simd IN ITEMS sse sse2 avx avx2)
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check_c_source_runs(
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"int main(void){return __builtin_cpu_supports(\"${_fftw_simd}\")?0:1;}"
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_fftw_cpu_has_${_fftw_simd}
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)
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if(_fftw_cpu_has_${_fftw_simd})
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set(_fftw_default_${_fftw_simd} ON)
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endif()
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endforeach()
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endif()
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endif()
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else()
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# Cross-compiling: conservative architecture-level fallback.
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if(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|arm64|ARM64")
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set(_fftw_default_neon ON)
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elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
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# SSE/SSE2 are baseline on all 64-bit x86 CPUs; AVX/AVX2 not assumed.
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set(_fftw_default_sse ON)
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set(_fftw_default_sse2 ON)
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endif()
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endif()
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option(FFTW_ENABLE_NEON "Enable FFTW NEON SIMD codelets (ARM64)" ${_fftw_default_neon})
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option(FFTW_ENABLE_SSE "Enable FFTW SSE SIMD codelets (x86)" ${_fftw_default_sse})
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option(FFTW_ENABLE_SSE2 "Enable FFTW SSE2 SIMD codelets (x86)" ${_fftw_default_sse2})
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option(FFTW_ENABLE_AVX "Enable FFTW AVX SIMD codelets (x86)" ${_fftw_default_avx})
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option(FFTW_ENABLE_AVX2 "Enable FFTW AVX2 SIMD codelets (x86)" ${_fftw_default_avx2})
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set(PROJ_FFTWD_DEPENDS "")
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if(ITK_USE_FFTWF)
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itk_download_attempt_check(FFTW)
@@ -76,14 +136,15 @@ if(NOT ITK_USE_SYSTEM_FFTW)
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-DCMAKE_INSTALL_LIBDIR:STRING=${CMAKE_INSTALL_LIBDIR}
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-DCMAKE_INSTALL_BINDIR:STRING=${CMAKE_INSTALL_BINDIR}
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-DDISABLE_FORTRAN:BOOL=ON
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-DENABLE_AVX:BOOL=OFF
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-DENABLE_AVX2:BOOL=OFF
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-DENABLE_AVX:BOOL=${FFTW_ENABLE_AVX}
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-DENABLE_AVX2:BOOL=${FFTW_ENABLE_AVX2}
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-DENABLE_FLOAT:BOOL=ON
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-DENABLE_LONG_DOUBLE:BOOL=OFF
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-DENABLE_NEON:BOOL=${FFTW_ENABLE_NEON}
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-DENABLE_OPENMP:BOOL=OFF
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-DENABLE_QUAD_PRECISION:BOOL=OFF
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-DENABLE_SSE:BOOL=OFF
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-DENABLE_SSE2:BOOL=OFF
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-DENABLE_SSE:BOOL=${FFTW_ENABLE_SSE}
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-DENABLE_SSE2:BOOL=${FFTW_ENABLE_SSE2}
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-DENABLE_THREADS:BOOL=ON
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-DCMAKE_APPLE_SILICON_PROCESSOR:STRING=${CMAKE_APPLE_SILICON_PROCESSOR}
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-DCMAKE_C_COMPILER_LAUNCHER:PATH=${CMAKE_C_COMPILER_LAUNCHER}
@@ -132,14 +193,15 @@ if(NOT ITK_USE_SYSTEM_FFTW)
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-DCMAKE_INSTALL_LIBDIR:STRING=${CMAKE_INSTALL_LIBDIR}
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-DCMAKE_INSTALL_BINDIR:STRING=${CMAKE_INSTALL_BINDIR}
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-DDISABLE_FORTRAN:BOOL=ON
135-
-DENABLE_AVX:BOOL=OFF
136-
-DENABLE_AVX2:BOOL=OFF
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-DENABLE_AVX:BOOL=${FFTW_ENABLE_AVX}
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-DENABLE_AVX2:BOOL=${FFTW_ENABLE_AVX2}
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-DENABLE_FLOAT:BOOL=OFF
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-DENABLE_LONG_DOUBLE:BOOL=OFF
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-DENABLE_NEON:BOOL=${FFTW_ENABLE_NEON}
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-DENABLE_OPENMP:BOOL=OFF
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-DENABLE_QUAD_PRECISION:BOOL=OFF
141-
-DENABLE_SSE:BOOL=OFF
142-
-DENABLE_SSE2:BOOL=OFF
203+
-DENABLE_SSE:BOOL=${FFTW_ENABLE_SSE}
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-DENABLE_SSE2:BOOL=${FFTW_ENABLE_SSE2}
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-DENABLE_THREADS:BOOL=ON
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-DCMAKE_APPLE_SILICON_PROCESSOR:STRING=${CMAKE_APPLE_SILICON_PROCESSOR}
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-DCMAKE_C_COMPILER_LAUNCHER:PATH=${CMAKE_C_COMPILER_LAUNCHER}

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