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coord/store: abstract SIMD alignment tests

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This commit is contained in:
Danny Robson 2017-01-05 16:46:01 +11:00
parent 353cf839d4
commit abedda1e5d
1 changed files with 37 additions and 16 deletions
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53
coord/store.hpp
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@ -22,24 +22,49 @@
#include "../platform.hpp"
#include <cstdlib>
#include <type_traits>
// Calculate a reasonable alignment for the given type and arity given what we
// know about the platform. Only intended to be used with alignas specifiers.
namespace util::coord::detail {
template <typename T>
constexpr
size_t
alignment (size_t S)
{
#if defined(__SSE_MATH__)
// Align to 16 if we have 4x floats on SSE/NEON. There are other
// possiblities, but we don't care about them right at this point.
if (!std::is_same<T,float>::value)
return alignof (T);
if (S % 4 == 0)
return 16;
#elif defined (__ARM_NEON__)
// TODO: deal with alignment issues before adding alignas specifiers
#endif
return alignof (T);
}
}
#define SIMD_ALIGN(S,T) alignas (util::coord::detail::alignment<T> (S))
namespace util::coord {
///////////////////////////////////////////////////////////////////////////
// Coordinate storage class.
//
// Types of arity multiples of 4 with payloads of at least 16 bytes
// (T >= uint16_t) are guaranteed to be aligned appropriately for SSE (see
// specialisations below).
// Types with trivially suitable arity are aligned appropriately to take
// advantage of native platform SIMD. eg, 4f types are aligned to 16 bytes
// on SSE platforms.
template <
size_t S,
typename T,
typename...
>
struct
alignas (
sizeof (T) * S % 16 == 0 && sizeof (T) * S >= 16 ? 16 : alignof (T)
)
SIMD_ALIGN(S,T)
store {
T data[S];
};
@ -63,9 +88,7 @@ namespace util::coord {
// TODO: expand this for other instruction sets. maybe switch on type.
template <typename T>
struct
alignas (
sizeof (T) * 4u >= 16 ? 16 : alignof (T)
)
SIMD_ALIGN(4,T)
store<4,T,rgba,hsv> {
union {
T data[4];
@ -101,9 +124,7 @@ namespace util::coord {
// TODO: expand this for other instruction sets. maybe switch on type.
template <typename T>
struct
alignas (
sizeof (T) * 4u >= 16 ? 16 : alignof (T)
)
SIMD_ALIGN(4,T)
store<4,T,xyzw> {
union {
T data[4];
@ -140,9 +161,7 @@ namespace util::coord {
// TODO: expand this for other instruction sets. maybe switch on type.
template <typename T>
struct
alignas (
sizeof (T) * 4u >= 16 ? 16 : alignof (T)
)
SIMD_ALIGN(4,T)
store<4,T,xyzw,stpq> {
union {
T data[4];
@ -173,7 +192,9 @@ namespace util::coord {
///////////////////////////////////////////////////////////////////////////
template <typename T>
struct store<4,T,wxyz,abcd> {
struct
SIMD_ALIGN(4,T)
store<4,T,wxyz,abcd> {
union {
T data[4];
struct { T w,x,y,z; };