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[SYCL] Add bfloat16 generic implementation for fmax, fmin #7732

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bader merged 4 commits into from
Dec 15, 2022
Merged

[SYCL] Add bfloat16 generic implementation for fmax, fmin #7732

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f7d6d06
[SYCL] Add bfloat16 generic implementation for fmax, fmin
jinge90 Dec 12, 2022
293fb42
1.Fix return type of isnan(bfloat16)
jinge90 Dec 12, 2022
ea8be62
Apply suggestions from code review
bader Dec 15, 2022
1bc646b
Fix formatting.
bader Dec 15, 2022
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78 changes: 51 additions & 27 deletions sycl/include/sycl/ext/oneapi/experimental/bfloat16_math.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,14 @@ uint32_t to_uint32_t(sycl::marray<bfloat16, N> x, size_t start) {
}
} // namespace detail

// According to bfloat16 format, NAN value's exponent field is 0xFF and
// significand has non-zero bits.
template <typename T>
std::enable_if_t<std::is_same<T, bfloat16>::value, T> isnan(T x) {
oneapi::detail::Bfloat16StorageT XBits = oneapi::detail::bfloat16ToBits(x);
return (((XBits & 0x7F80) == 0x7F80) && (XBits & 0x7F)) ? true : false;
}

template <typename T>
std::enable_if_t<std::is_same<T, bfloat16>::value, T> fabs(T x) {
#if defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
Expand Down Expand Up @@ -74,20 +82,31 @@ std::enable_if_t<std::is_same<T, bfloat16>::value, T> fmin(T x, T y) {
oneapi::detail::Bfloat16StorageT YBits = oneapi::detail::bfloat16ToBits(y);
return oneapi::detail::bitsToBfloat16(__clc_fmin(XBits, YBits));
#else
std::ignore = x;
std::ignore = y;
throw runtime_error(
"bfloat16 math functions are not currently supported on the host device.",
PI_ERROR_INVALID_DEVICE);
static const oneapi::detail::Bfloat16StorageT CanonicalNan = 0x7FC0;
oneapi::detail::Bfloat16StorageT XBits = oneapi::detail::bfloat16ToBits(x);
oneapi::detail::Bfloat16StorageT YBits = oneapi::detail::bfloat16ToBits(y);
if (isnan(x) && isnan(y))
return oneapi::detail::bitsToBfloat16(CanonicalNan);

if (isnan(x))
return y;
else if (isnan(y))
return x;
else if (((XBits | YBits) ==
static_cast<oneapi::detail::Bfloat16StorageT>(0x8000)) &&
!(XBits & YBits))
return oneapi::detail::bitsToBfloat16(
static_cast<oneapi::detail::Bfloat16StorageT>(0x8000));
else
return (x < y) ? x : y;
#endif // defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
}

template <size_t N>
sycl::marray<bfloat16, N> fmin(sycl::marray<bfloat16, N> x,
sycl::marray<bfloat16, N> y) {
#if defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
sycl::marray<bfloat16, N> res;

#if defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
for (size_t i = 0; i < N / 2; i++) {
auto partial_res = __clc_fmin(detail::to_uint32_t(x, i * 2),
detail::to_uint32_t(y, i * 2));
Expand All @@ -101,15 +120,12 @@ sycl::marray<bfloat16, N> fmin(sycl::marray<bfloat16, N> x,
oneapi::detail::bfloat16ToBits(y[N - 1]);
res[N - 1] = oneapi::detail::bitsToBfloat16(__clc_fmin(XBits, YBits));
}

return res;
#else
std::ignore = x;
std::ignore = y;
throw runtime_error(
"bfloat16 math functions are not currently supported on the host device.",
PI_ERROR_INVALID_DEVICE);
for (size_t i = 0; i < N; i++) {
res[i] = fmin(x[i], y[i]);
}
#endif // defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
return res;
}

template <typename T>
Expand All @@ -119,20 +135,30 @@ std::enable_if_t<std::is_same<T, bfloat16>::value, T> fmax(T x, T y) {
oneapi::detail::Bfloat16StorageT YBits = oneapi::detail::bfloat16ToBits(y);
return oneapi::detail::bitsToBfloat16(__clc_fmax(XBits, YBits));
#else
std::ignore = x;
std::ignore = y;
throw runtime_error(
"bfloat16 math functions are not currently supported on the host device.",
PI_ERROR_INVALID_DEVICE);
static const oneapi::detail::Bfloat16StorageT CanonicalNan = 0x7FC0;
oneapi::detail::Bfloat16StorageT XBits = oneapi::detail::bfloat16ToBits(x);
oneapi::detail::Bfloat16StorageT YBits = oneapi::detail::bfloat16ToBits(y);
if (isnan(x) && isnan(y))
return oneapi::detail::bitsToBfloat16(CanonicalNan);

if (isnan(x))
return y;
else if (isnan(y))
return x;
else if (((XBits | YBits) ==
static_cast<oneapi::detail::Bfloat16StorageT>(0x8000)) &&
!(XBits & YBits))
return oneapi::detail::bitsToBfloat16(0);
else
return (x > y) ? x : y;
#endif // defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
}

template <size_t N>
sycl::marray<bfloat16, N> fmax(sycl::marray<bfloat16, N> x,
sycl::marray<bfloat16, N> y) {
#if defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
sycl::marray<bfloat16, N> res;

#if defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
for (size_t i = 0; i < N / 2; i++) {
auto partial_res = __clc_fmax(detail::to_uint32_t(x, i * 2),
detail::to_uint32_t(y, i * 2));
Expand All @@ -146,14 +172,12 @@ sycl::marray<bfloat16, N> fmax(sycl::marray<bfloat16, N> x,
oneapi::detail::bfloat16ToBits(y[N - 1]);
res[N - 1] = oneapi::detail::bitsToBfloat16(__clc_fmax(XBits, YBits));
}
return res;
#else
std::ignore = x;
std::ignore = y;
throw runtime_error(
"bfloat16 math functions are not currently supported on the host device.",
PI_ERROR_INVALID_DEVICE);
for (size_t i = 0; i < N; i++) {
res[i] = fmax(x[i], y[i]);
}
#endif // defined(__SYCL_DEVICE_ONLY__) && defined(__NVPTX__)
return res;
}

template <typename T>
Expand Down