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Detect L1 cache size at compile time #419

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Detect L1 cache size at compile time #419

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24 changes: 24 additions & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -203,6 +203,30 @@ else()
endif()
endif()

# -----------------------------------------------------------------------------
# Cache line size detection
# -----------------------------------------------------------------------------
if (CMAKE_CROSSCOMPILING)
message(STATUS "Cross-compiling - cache line size detection disabled")
else()
if (CMAKE_SYSTEM_PROCESSOR MATCHES "^(aarch64.*|AARCH64.*|arm64.*)")
if (APPLE)
execute_process(COMMAND sysctl -n hw.cachelinesize
OUTPUT_VARIABLE L1_DCACHE_LINE_SIZE
OUTPUT_STRIP_TRAILING_WHITESPACE)
else()
if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
execute_process(COMMAND getconf LEVEL1_DCACHE_LINESIZE
OUTPUT_VARIABLE L1_DCACHE_LINE_SIZE
OUTPUT_STRIP_TRAILING_WHITESPACE)
endif()
endif()
endif()
endif()
if (L1_DCACHE_LINE_SIZE)
list(APPEND mi_defines MI_CACHE_LINE=${L1_DCACHE_LINE_SIZE})
endif()

# -----------------------------------------------------------------------------
# Install and output names
# -----------------------------------------------------------------------------
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25 changes: 24 additions & 1 deletion include/mimalloc-internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,30 @@ terms of the MIT license. A copy of the license can be found in the file
#define mi_trace_message(...)
#endif

#define MI_CACHE_LINE 64
// Determine system L1 cache line size at compile time for purposes of alignment.
#ifndef MI_CACHE_LINE
#if defined(__i386__) || defined(__x86_64__)
#define MI_CACHE_LINE 64
#elif defined(__aarch64__)
// FIXME: read special register ctr_el0 to get L1 dcache size.
#define MI_CACHE_LINE 64
#elif defined(__arm__)
// The cache line sizes for Arm depend on implementations, not architectures.
// There are even implementations with cache line sizes configurable at boot time.
#if __ARM_ARCH__ == 7
#define MI_CACHE_LINE 64
#else
// TODO: list known Arm implementations
#define MI_CACHE_LINE 32
#endif
#endif
#endif

#ifndef MI_CACHE_LINE
// A reasonable default value
#define MI_CACHE_LINE 64
#endif

#if defined(_MSC_VER)
#pragma warning(disable:4127) // suppress constant conditional warning (due to MI_SECURE paths)
#define mi_decl_noinline __declspec(noinline)
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