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Make the cached hardware support atomic in the C++ build too #950

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Merged
lemire merged 2 commits into from
Nov 3, 2026
Merged

Make the cached hardware support atomic in the C++ build too #950

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d41724e
Make the cached hardware support atomic in the C++ build too
lemire Nov 3, 2026
2a0345a
Apply clang-format
lemire Nov 3, 2026
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32 changes: 17 additions & 15 deletions src/isadetection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -364,6 +364,20 @@ static inline uint32_t croaring_detect_supported_architectures(void) {

#endif // CROARING_IS_X64 || CROARING_IS_ARM64

// The cached result of croaring_hardware_support(), which threads calling it
// for the first time all write.
#if CROARING_ATOMIC_IMPL == CROARING_ATOMIC_IMPL_CPP
typedef std::atomic<int> croaring_atomic_int;
#define CROARING_SUPPORT_UNKNOWN \
{ 0xFFFFFFF } // no copy before C++17
#elif CROARING_ATOMIC_IMPL == CROARING_ATOMIC_IMPL_C
typedef _Atomic int croaring_atomic_int;
#define CROARING_SUPPORT_UNKNOWN 0xFFFFFFF
#else
typedef int croaring_atomic_int;
#define CROARING_SUPPORT_UNKNOWN 0xFFFFFFF
#endif

#if CROARING_IS_X64 // x64

#ifdef ROARING_DISABLE_AVX
Expand All @@ -379,11 +393,7 @@ int croaring_hardware_support(void) {
#elif defined(__AVX2__)

int croaring_hardware_support(void) {
static
#if CROARING_ATOMIC_IMPL == CROARING_ATOMIC_IMPL_C
_Atomic
#endif
int support = 0xFFFFFFF;
static croaring_atomic_int support = CROARING_SUPPORT_UNKNOWN;
if (support == 0xFFFFFFF) {
bool avx512_support = false;
#if CROARING_COMPILER_SUPPORTS_AVX512
Expand All @@ -399,11 +409,7 @@ int croaring_hardware_support(void) {
#else

int croaring_hardware_support(void) {
static
#if CROARING_ATOMIC_IMPL == CROARING_ATOMIC_IMPL_C
_Atomic
#endif
int support = 0xFFFFFFF;
static croaring_atomic_int support = CROARING_SUPPORT_UNKNOWN;
if (support == 0xFFFFFFF) {
bool has_avx2 = (croaring_detect_supported_architectures() &
CROARING_AVX2) == CROARING_AVX2;
Expand All @@ -424,11 +430,7 @@ int croaring_hardware_support(void) {
#if CROARING_IS_ARM64

int croaring_hardware_support(void) {
static
#if CROARING_ATOMIC_IMPL == CROARING_ATOMIC_IMPL_C
_Atomic
#endif
int support = 0xFFFFFFF;
static croaring_atomic_int support = CROARING_SUPPORT_UNKNOWN;
if (support == 0xFFFFFFF) {
uint32_t isa = croaring_detect_supported_architectures();
support = ((isa & CROARING_SVE) ? ROARING_SUPPORTS_SVE : 0) |
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