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COMP: Remove hardcoded -march=corei7, -mtune=generic, and dead code #6049

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Merged
hjmjohnson merged 2 commits into from
Apr 13, 2026
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COMP: Remove hardcoded -march=corei7, -mtune=generic, and dead code #6049

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7c0bfe8
COMP: Remove hardcoded -march=corei7, -mtune=generic, and dead code
hjmjohnson Apr 13, 2026
c5da273
COMP: Remove dead MSVC AVX detection and InstructionSetOptimizationFlags
hjmjohnson Apr 13, 2026
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132 changes: 12 additions & 120 deletions CMake/ITKSetStandardCompilerFlags.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -151,81 +151,6 @@ function(check_compiler_warning_flags c_warning_flags_var cxx_warning_flags_var)
set(${cxx_warning_flags_var} "${CMAKE_CXX_WARNING_FLAGS}" PARENT_SCOPE)
endfunction()

# Check for the presence of AVX and figure out the flags to use for it.
# Adapted from https://gist.github.com/UnaNancyOwen/263c243ae1e05a2f9d0e
function(check_avx_flags avx_flags_var)
set(avx_flags_var)

include(CheckCXXSourceRuns)
set(_safe_cmake_required_flags "${CMAKE_REQUIRED_FLAGS}")
set(CMAKE_REQUIRED_FLAGS)

# Check AVX
if(MSVC)
set(CMAKE_REQUIRED_FLAGS "/arch:AVX") # set flags to be used in check_cxx_source_runs below
endif()
check_cxx_source_runs(
"
#include <immintrin.h>
int main()
{
__m256 a, b, c;
const float src[8] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f, 8.0f };
float dst[8];
a = _mm256_loadu_ps(src);
b = _mm256_loadu_ps(src);
c = _mm256_add_ps(a, b);
_mm256_storeu_ps(dst, c);

for(int i = 0; i < 8; i++){
if(( src[i] + src[i]) != dst[i]){
return -1;
}
}

return 0;
}"
have_avx_extensions_var
)

# Check AVX2
if(MSVC)
set(CMAKE_REQUIRED_FLAGS "/arch:AVX2") # set flags to be used in check_cxx_source_runs below
endif()
check_cxx_source_runs(
"
#include <immintrin.h>
int main()
{
__m256i a, b, c;
const int src[8] = { 1, 2, 3, 4, 5, 6, 7, 8 };
int dst[8];
a = _mm256_loadu_si256( (__m256i*)src);
b = _mm256_loadu_si256( (__m256i*)src);
c = _mm256_add_epi32( a, b);
_mm256_storeu_si256( (__m256i*)dst, c);

for(int i = 0; i < 8; i++){
if(( src[i] + src[i]) != dst[i]){
return -1;
}
}

return 0;
}"
have_avx2_extensions_var
)

set(CMAKE_REQUIRED_FLAGS "${_safe_cmake_required_flags}")

# Set Flags
if(have_avx2_extensions_var AND MSVC)
set(avx_flags_var "${avx_flags_var} /arch:AVX2")
elseif(have_avx_extensions_var AND MSVC)
set(avx_flags_var "${avx_flags_var} /arch:AVX")
endif()
endfunction()

# Check for the presence of SSE2.
# Adapted from the AVX check and https://github.com/InsightSoftwareConsortium/ITK/blob/4cbe24cb4a45d689cadd56d554b8ccf3584a5ca6/Modules/ThirdParty/VNL/src/vxl/config/cmake/config/vxl_platform_tests.cxx#L164-L178
function(check_sse2_flags sse2_flags_var)
Expand Down Expand Up @@ -279,51 +204,18 @@ function(
set(${c_optimization_flags_var} "" PARENT_SCOPE)
set(${cxx_optimization_flags_var} "" PARENT_SCOPE)

if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(x86_64|AMD64)")
if(MSVC)
check_avx_flags(InstructionSetOptimizationFlags)
if("${CMAKE_SIZEOF_VOID_P}" EQUAL "4")
list(
APPEND
InstructionSetOptimizationFlags
/arch:SSE
/arch:SSE2
)
endif()
elseif(NOT EMSCRIPTEN OR WASI)
if(${CMAKE_C_COMPILER} MATCHES "icc.*$")
set(USING_INTEL_ICC_COMPILER TRUE)
endif()
if(${CMAKE_CXX_COMPILER} MATCHES "icpc.*$")
set(USING_INTEL_ICC_COMPILER TRUE)
endif()
if(USING_INTEL_ICC_COMPILER)
set(InstructionSetOptimizationFlags "")
else()
set(InstructionSetOptimizationFlags "")
endif()

# Check this list on C compiler only
set(c_flags "")

# Check this list on C++ compiler only
set(cxx_flags "")

# Check this list on both C and C++ compilers
set(
InstructionSetOptimizationFlags
# https://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/i386-and-x86_002d64-Options.html
# NOTE the corei7 release date was 2008
#-mtune=native # Tune the code for the computer used compile ITK, but allow running on generic cpu archetectures
-mtune=generic # for reproducible results https://github.com/InsightSoftwareConsortium/ITK/issues/1939
-march=corei7 # Use ABI settings to support corei7 (circa 2008 ABI feature sets, core-avx circa 2013)
)
endif()
set(c_and_cxx_flags ${InstructionSetOptimizationFlags})
endif()

check_c_compiler_flags(CMAKE_C_WARNING_FLAGS ${c_and_cxx_flags} ${c_flags})
check_cxx_compiler_flags(CMAKE_CXX_WARNING_FLAGS ${c_and_cxx_flags} ${cxx_flags})
# No architecture-specific optimization flags are set by default,
# ensuring maximum redistributability for pip wheels, Docker images,
# and hardware translation layers (Rosetta, QEMU).
# Users building for local performance should add -march=native via
# CMAKE_C_FLAGS/CMAKE_CXX_FLAGS or CMakeUserPresets.json.
# NOTE: When using -march=native on CPUs with AVX-512, also add
# -mprefer-vector-width=256 to avoid Intel CPU frequency throttling.
# See: https://github.com/InsightSoftwareConsortium/ITK/issues/2634
# https://github.com/InsightSoftwareConsortium/ITK/issues/1939

check_c_compiler_flags(CMAKE_C_WARNING_FLAGS)
check_cxx_compiler_flags(CMAKE_CXX_WARNING_FLAGS)

set(${c_optimization_flags_var} "${CMAKE_C_WARNING_FLAGS}" PARENT_SCOPE)
set(${cxx_optimization_flags_var} "${CMAKE_CXX_WARNING_FLAGS}" PARENT_SCOPE)
Expand Down
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