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[OpenMP] Use __builtin_bit_cast instead of UB type punning #122325

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Merged
merged 1 commit into from
Jan 9, 2025
Merged

[OpenMP] Use __builtin_bit_cast instead of UB type punning #122325

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5 changes: 5 additions & 0 deletions offload/DeviceRTL/include/DeviceUtils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,11 @@ struct remove_addrspace<T [[clang::address_space(N)]]> : type_identity<T> {};
template <class T>
using remove_addrspace_t = typename remove_addrspace<T>::type;

template <typename To, typename From> inline To bitCast(From V) {
static_assert(sizeof(To) == sizeof(From), "Bad conversion");
return __builtin_bit_cast(To, V);
}

/// Return the value \p Var from thread Id \p SrcLane in the warp if the thread
/// is identified by \p Mask.
int32_t shuffle(uint64_t Mask, int32_t Var, int32_t SrcLane, int32_t Width);
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32 changes: 16 additions & 16 deletions offload/DeviceRTL/include/Synchronization.h
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Expand Up @@ -98,20 +98,20 @@ template <typename Ty, typename V = utils::remove_addrspace_t<Ty>>
utils::enable_if_t<utils::is_same_v<V, float>, V>
max(Ty *Address, V Val, atomic::OrderingTy Ordering) {
if (Val >= 0)
return utils::convertViaPun<float>(
max((int32_t *)Address, utils::convertViaPun<int32_t>(Val), Ordering));
return utils::convertViaPun<float>(
min((uint32_t *)Address, utils::convertViaPun<uint32_t>(Val), Ordering));
return utils::bitCast<float>(
max((int32_t *)Address, utils::bitCast<int32_t>(Val), Ordering));
return utils::bitCast<float>(
min((uint32_t *)Address, utils::bitCast<uint32_t>(Val), Ordering));
}

template <typename Ty, typename V = utils::remove_addrspace_t<Ty>>
utils::enable_if_t<utils::is_same_v<V, double>, V>
max(Ty *Address, V Val, atomic::OrderingTy Ordering) {
if (Val >= 0)
return utils::convertViaPun<double>(
max((int64_t *)Address, utils::convertViaPun<int64_t>(Val), Ordering));
return utils::convertViaPun<double>(
min((uint64_t *)Address, utils::convertViaPun<uint64_t>(Val), Ordering));
return utils::bitCast<double>(
max((int64_t *)Address, utils::bitCast<int64_t>(Val), Ordering));
return utils::bitCast<double>(
min((uint64_t *)Address, utils::bitCast<uint64_t>(Val), Ordering));
}

template <typename Ty, typename V = utils::remove_addrspace_t<Ty>>
Expand All @@ -126,10 +126,10 @@ template <typename Ty, typename V = utils::remove_addrspace_t<Ty>>
utils::enable_if_t<utils::is_same_v<V, float>, V>
min(Ty *Address, V Val, atomic::OrderingTy Ordering) {
if (Val >= 0)
return utils::convertViaPun<float>(
min((int32_t *)Address, utils::convertViaPun<int32_t>(Val), Ordering));
return utils::convertViaPun<float>(
max((uint32_t *)Address, utils::convertViaPun<uint32_t>(Val), Ordering));
return utils::bitCast<float>(
min((int32_t *)Address, utils::bitCast<int32_t>(Val), Ordering));
return utils::bitCast<float>(
max((uint32_t *)Address, utils::bitCast<uint32_t>(Val), Ordering));
}

// TODO: Implement this with __atomic_fetch_max and remove the duplication.
Expand All @@ -138,10 +138,10 @@ utils::enable_if_t<utils::is_same_v<V, double>, V>
min(Ty *Address, utils::remove_addrspace_t<Ty> Val,
atomic::OrderingTy Ordering) {
if (Val >= 0)
return utils::convertViaPun<double>(
min((int64_t *)Address, utils::convertViaPun<int64_t>(Val), Ordering));
return utils::convertViaPun<double>(
max((uint64_t *)Address, utils::convertViaPun<uint64_t>(Val), Ordering));
return utils::bitCast<double>(
min((int64_t *)Address, utils::bitCast<int64_t>(Val), Ordering));
return utils::bitCast<double>(
max((uint64_t *)Address, utils::bitCast<uint64_t>(Val), Ordering));
}

template <typename Ty, typename V = utils::remove_addrspace_t<Ty>>
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8 changes: 4 additions & 4 deletions offload/DeviceRTL/src/Mapping.cpp
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Expand Up @@ -371,8 +371,8 @@ int ompx_shfl_down_sync_i(uint64_t mask, int var, unsigned delta, int width) {

float ompx_shfl_down_sync_f(uint64_t mask, float var, unsigned delta,
int width) {
return utils::convertViaPun<float>(utils::shuffleDown(
mask, utils::convertViaPun<int32_t>(var), delta, width));
return utils::bitCast<float>(
utils::shuffleDown(mask, utils::bitCast<int32_t>(var), delta, width));
}

long ompx_shfl_down_sync_l(uint64_t mask, long var, unsigned delta, int width) {
Expand All @@ -381,8 +381,8 @@ long ompx_shfl_down_sync_l(uint64_t mask, long var, unsigned delta, int width) {

double ompx_shfl_down_sync_d(uint64_t mask, double var, unsigned delta,
int width) {
return utils::convertViaPun<double>(utils::shuffleDown(
mask, utils::convertViaPun<int64_t>(var), delta, width));
return utils::bitCast<double>(
utils::shuffleDown(mask, utils::bitCast<int64_t>(var), delta, width));
}
}

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5 changes: 0 additions & 5 deletions offload/include/Shared/Utils.h
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Expand Up @@ -68,11 +68,6 @@ inline uint32_t popc(uint64_t V) {
return __builtin_popcountl(V);
}

template <typename DstTy, typename SrcTy> inline DstTy convertViaPun(SrcTy V) {
static_assert(sizeof(DstTy) == sizeof(SrcTy), "Bad conversion");
return *((DstTy *)(&V));
}

} // namespace utils

#endif // OMPTARGET_SHARED_UTILS_H
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