thier3: tricky rotation based state storing...

This reverts commit d487bb111b93f4ab186147fd876373f46eff0e59.

magyarsort.h

@@ -310,6 +310,7 @@ namespace MagyarSort {
 
 	/* SORT */
 
+	// FIXME: I think the GC is not working because these are separate functions generated with sep static threadlocals!!!
 	/*
 	 * Sort the given array (in-place sorting) with the given size.
 	 *

threepass_xbit.h

@@ -55,9 +55,9 @@ static inline void threepass_xb(uint32_t *a, uint32_t *buf, int n) noexcept {
 	}
 
 	/* Count prefix sums - try as much ILP as possible because bigger arrays than usual! */
-	uint32_t prev1 = 0;
+	int prev1 = -1;
-	uint32_t prev2 = 0;
+	int prev2 = -1;
-	uint32_t prev3 = 0;
+	int prev3 = -1;
 	uint32_t common = min3u32_xb(
 		(1 << TPBX1),
 		(1 << TPBX2),
@@ -89,47 +89,37 @@ static inline void threepass_xb(uint32_t *a, uint32_t *buf, int n) noexcept {
 		prev3 = bucket3[j];
 	}
 
-	// Bottom digit a->buf
+	/* Move elements (the 3 pass): This utilizes frewr trick to overwrite keys (elements) by ror-ing them */
-	// right-to-left to ensure already sorted digits order we keep for iterations
+	/* This rewrites the key into its rotated state to save some pipeline stalls. (3 rotates happen and in the end its ok) */
-	#pragma GCC unroll 48
+	/* right-to-left to ensure already sorted digits order we keep for iterations */
-	for(uint32_t i = n; i > 0; --i) {
-		// Prefetch caches
-		//__builtin_prefetch(&a[i-8]);
-		// Get num and its new offset / location
-		auto num = a[i - 1];
-		auto bkeyni = (num >> shr3) & mask3;
-		auto offset = --bucket3[bkeyni];
 
-		// Add to the proper target location
+	/* Bottom digit a->buf */
-		buf[offset] = num;
+	#pragma GCC unroll 80
+	for(uint32_t i = n; i > 0; --i) {
+		uint32_t num = a[i - 1];
+		/* save rotated into the masked, bucketed loc */
+		buf[bucket3[num & mask3]--] = (num >> TPBX3) | (num << (32 - TPBX3));
+		//__builtin_prefetch(&buf[bucket3[num & mask3] - 2]);
 	}
-	// Mid digit buf->a
-	// right-to-left to ensure already sorted digits order we keep for iterations
-	#pragma GCC unroll 48
-	for(uint32_t i = n; i > 0; --i) {
-		// Prefetch caches
-		//__builtin_prefetch(&buf[i-8]);
-		// Get num and its new offset / location
-		auto num = buf[i - 1];
-		auto bkeyni = (num >> shr2) & mask2;
-		auto offset = --bucket2[bkeyni];
 
-		// Add to the proper target location
+	/* Mid digit buf->a */
-		a[offset] = num;
+	#pragma GCC unroll 80
+	for(uint32_t i = n; i > 0; --i) {
+		uint32_t num = buf[i - 1];
+		/* save rotated into the masked, bucketed loc */
+		a[bucket2[num & mask2]--] = (num >> TPBX2) | (num << (32 - TPBX2));
+		//__builtin_prefetch(&a[bucket2[num & mask2] - 2]);
 	}
-	// Top digit a->buf
-	// right-to-left to ensure already sorted digits order we keep for iterations
-	#pragma GCC unroll 48
-	for(uint32_t i = n; i > 0; --i) {
-		// Prefetch caches
-		// __builtin_prefetch(&a[i-16]);
-		// Get num and its new offset / location
-		auto num = a[i - 1];
-		auto bkeyni = (num >> shr1) & mask1;
-		auto offset = --bucket1[bkeyni];
 
-		// Add to the proper target location
+	/* Top digit a->buf */
-		buf[offset] = num;
+	#pragma GCC unroll 80
+	for(uint32_t i = n; i > 0; --i) {
+		uint32_t num = a[i - 1];
+		/* Reconstruct the original key in this element by where its stuff is stored */
+		constexpr int rot = TPBX1 + (32 - TPBX1 - TPBX2 - TPBX3);
+		/* save rotated into the masked, bucketed loc */
+		buf[bucket1[num & mask1]--] = (num >> rot) | (num << (32 - rot));
+		//__builtin_prefetch(&buf[bucket1[num & mask1] - 2]);
 	}
 }
 

ypsu.cpp

@@ -231,8 +231,11 @@ static inline void do_thier3(uint32_t *a, int n) noexcept {
 /** rthier */
 static inline void do_rthier(uint32_t *a, int n) noexcept {
 	assert(n * uint32_t(sizeof(a[0])) <= INT_MAX);
+	if(n > 140000000) {
+		/* Helps a bit against our worst cases in big numbers */
 		uint32_t junk;
 		randominus(a, n, junk);
+	}
 	std::vector<uint32_t> tmp(n);
 	thiersort3(a, &(tmp[0]), n);
 }
@@ -945,6 +948,7 @@ int main(int argc, char **argv) {
 	});
     assert(w == expected);
 
+	/*
     w = v;
     measure(inputtype, "rmagyar", [&] {
 			uint32_t junk;
@@ -952,6 +956,7 @@ int main(int argc, char **argv) {
 			MagyarSort::sort<uint32_t>(&w[0], w.size());
 	});
     assert(w == expected);
+	*/
 
     w = v;
     measure(inputtype, "gptbuck", [&] { gpt_bucket_sort(&w[0], w.size()); });