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trying some prefetch - not that good yet

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This commit is contained in:
Richard Thier 2021-12-17 21:42:35 +01:00
parent 0b4eb5e5a6
commit 3fdcaad537
1 changed files with 6 additions and 0 deletions
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6
magyarsort.h
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@ -89,6 +89,9 @@ namespace MagyarSort {
static inline void countOccurences(uint32_t arr[], COUNTER_TYP size, COUNTER_TYP *radicsOut) noexcept {
#pragma GCC unroll 64
for(COUNTER_TYP i = 0; i < size; ++i) {
// Prefetch caches
__builtin_prefetch(&arr[i]); // TODO: is good?
__builtin_prefetch(&arr[i + 64]);
// Creates no object, struct is empty
OccurenceMagic<DIGITS - 1, COUNTER_TYP>(arr, i, radicsOut);
}
@ -139,6 +142,9 @@ namespace MagyarSort {
#pragma GCC unroll 64
for(COUNTER_TYP i = size; i > 0; --i) { // right-to-left to ensure already sorted digits order we keep for iterations
// Prefetch caches
__builtin_prefetch(&from[i]); // TODO: is good?
if(i >= 64) { __builtin_prefetch(&from[i - 64]); } // TODO: manually unroll?
// Get num and its new offset / location
auto num = from[i - 1];
auto digVal = getDigit<DIGIT>(num);