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jhuber6jhuber6
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cleanup and comments
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‎libc/src/__support/CPP/simd.h‎

Lines changed: 68 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -34,9 +34,6 @@ namespace cpp {
3434

3535
namespace internal {
3636

37-
template <typename T>
38-
using get_as_integer_type_t = unsigned _BitInt(sizeof(T) * CHAR_BIT);
39-
4037
#if defined(LIBC_TARGET_CPU_HAS_AVX512F)
4138
template <typename T>
4239
LIBC_INLINE_VAR constexpr size_t native_vector_size = 64 / sizeof(T);
@@ -50,10 +47,6 @@ LIBC_INLINE_VAR constexpr size_t native_vector_size = 16 / sizeof(T);
5047
template <typename T> LIBC_INLINE constexpr size_t native_vector_size = 1;
5148
#endif
5249

53-
template <typename T> LIBC_INLINE constexpr T poison() {
54-
return __builtin_nondeterministic_value(T());
55-
}
56-
5750
} // namespace internal
5851

5952
// Type aliases.
@@ -64,6 +57,74 @@ using simd = T [[clang::ext_vector_type(N)]];
6457
template <typename T>
6558
using simd_mask = simd<bool, internal::native_vector_size<T>>;
6659

60+
namespace internal {
61+
62+
template <typename T>
63+
using get_as_integer_type_t = unsigned _BitInt(sizeof(T) * CHAR_BIT);
64+
65+
template <typename T> LIBC_INLINE constexpr T poison() {
66+
return __builtin_nondeterministic_value(T());
67+
}
68+
69+
template <typename T, size_t N, size_t OriginalSize, size_t... Indices>
70+
LIBC_INLINE constexpr static cpp::simd<T, sizeof...(Indices)>
71+
extend(cpp::simd<T, N> x, cpp::index_sequence<Indices...>) {
72+
return __builtin_shufflevector(
73+
x, x, (Indices < OriginalSize ? static_cast<int>(Indices) : -1)...);
74+
}
75+
76+
template <typename T, size_t N, size_t TargetSize, size_t OriginalSize>
77+
LIBC_INLINE constexpr static auto extend(cpp::simd<T, N> x) {
78+
// Recursively resize an input vector to the target size, increasing its size
79+
// by at most double the input size each step.
80+
if constexpr (N == TargetSize)
81+
return x;
82+
else if constexpr (TargetSize <= 2 * N)
83+
return extend<T, N, TargetSize>(x, cpp::make_index_sequence<TargetSize>{});
84+
else
85+
return extend<T, 2 * N, TargetSize, OriginalSize>(
86+
extend<T, N, 2 * N>(x, cpp::make_index_sequence<2 * N>{}));
87+
}
88+
89+
template <typename T, size_t N, size_t M, size_t... Indices>
90+
LIBC_INLINE constexpr static cpp::simd<T, N + M>
91+
concat(cpp::simd<T, N> x, cpp::simd<T, M> y, cpp::index_sequence<Indices...>) {
92+
constexpr size_t Length = (N > M ? N : M);
93+
auto remap = [](size_t idx) -> int {
94+
if (idx < N)
95+
return static_cast<int>(idx);
96+
if (idx < N + M)
97+
return static_cast<int>((idx - N) + Length);
98+
return -1;
99+
};
100+
101+
// Extend the input vectors until they are the same size, then use the indices
102+
// to shuffle in only the indices that correspond to the original values.
103+
auto x_ext = extend<T, N, Length, N>(x);
104+
auto y_ext = extend<T, M, Length, M>(y);
105+
return __builtin_shufflevector(x_ext, y_ext, remap(Indices)...);
106+
}
107+
108+
template <typename T, size_t N, size_t Count, size_t Offset, size_t... Indices>
109+
LIBC_INLINE constexpr static cpp::simd<T, Count>
110+
slice(cpp::simd<T, N> x, cpp::index_sequence<Indices...>) {
111+
return __builtin_shufflevector(x, x, (Offset + Indices)...);
112+
}
113+
114+
template <typename T, size_t N, size_t Offset, size_t Head, size_t... Tail>
115+
LIBC_INLINE constexpr static auto split(cpp::simd<T, N> x) {
116+
// Recursively splits the input vector by walking the variadic template list,
117+
// increasing our current head each call.
118+
auto first = cpp::make_tuple(
119+
slice<T, N, Head, Offset>(x, cpp::make_index_sequence<Head>{}));
120+
if constexpr (sizeof...(Tail) > 0)
121+
return cpp::tuple_cat(first, split<T, N, Offset + Head, Tail...>(x));
122+
else
123+
return first;
124+
}
125+
126+
} // namespace internal
127+
67128
// Type trait helpers.
68129
template <typename T>
69130
struct simd_size : cpp::integral_constant<size_t, __builtin_vectorelements(T)> {
@@ -276,58 +337,6 @@ LIBC_INLINE constexpr static simd<T, N> select(simd<bool, N> m, simd<T, N> x,
276337
return m ? x : y;
277338
}
278339

279-
namespace internal {
280-
template <typename T, size_t N, size_t O, size_t... I>
281-
LIBC_INLINE constexpr static cpp::simd<T, sizeof...(I)>
282-
extend(cpp::simd<T, N> x, cpp::index_sequence<I...>) {
283-
return __builtin_shufflevector(x, x, (I < O ? static_cast<int>(I) : -1)...);
284-
}
285-
template <typename T, size_t N, size_t M, size_t O>
286-
LIBC_INLINE constexpr static auto extend(cpp::simd<T, N> x) {
287-
if constexpr (N == M)
288-
return x;
289-
else if constexpr (M <= 2 * N)
290-
return extend<T, N, M>(x, cpp::make_index_sequence<M>{});
291-
else
292-
return extend<T, 2 * N, M, O>(
293-
extend<T, N, 2 * N>(x, cpp::make_index_sequence<2 * N>{}));
294-
}
295-
template <typename T, size_t N, size_t M, size_t... I>
296-
LIBC_INLINE constexpr static cpp::simd<T, N + M>
297-
concat(cpp::simd<T, N> x, cpp::simd<T, M> y, cpp::index_sequence<I...>) {
298-
constexpr size_t L = (N > M ? N : M);
299-
300-
auto x_ext = extend<T, N, L, N>(x);
301-
auto y_ext = extend<T, M, L, M>(y);
302-
303-
auto remap = [](size_t idx) -> int {
304-
if (idx < N)
305-
return static_cast<int>(idx);
306-
if (idx < N + M)
307-
return static_cast<int>((idx - N) + L);
308-
return -1;
309-
};
310-
311-
return __builtin_shufflevector(x_ext, y_ext, remap(I)...);
312-
}
313-
314-
template <typename T, size_t N, size_t Count, size_t Offset, size_t... I>
315-
LIBC_INLINE constexpr static cpp::simd<T, Count>
316-
slice(cpp::simd<T, N> x, cpp::index_sequence<I...>) {
317-
return __builtin_shufflevector(x, x, (Offset + I)...);
318-
}
319-
template <typename T, size_t N, size_t Offset, size_t Head, size_t... Tail>
320-
LIBC_INLINE constexpr static auto split(cpp::simd<T, N> x) {
321-
auto first = cpp::make_tuple(
322-
slice<T, N, Head, Offset>(x, cpp::make_index_sequence<Head>{}));
323-
if constexpr (sizeof...(Tail) > 0)
324-
return cpp::tuple_cat(first, split<T, N, Offset + Head, Tail...>(x));
325-
else
326-
return first;
327-
}
328-
329-
} // namespace internal
330-
331340
// Shuffling helpers.
332341
template <typename T, size_t N, size_t M>
333342
LIBC_INLINE constexpr static auto concat(cpp::simd<T, N> x, cpp::simd<T, M> y) {

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