Start on tuning flint_mpn_mulhigh_n

Author: albinahlback

src/tune/mpn_extras/mulhigh_0.c

@@ -0,0 +1,25 @@
+/*
+    Copyright (C) 2024 Albin Ahlbäck
+
+    This file is part of FLINT.
+
+    FLINT is free software: you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
+*/
+
+#include "flint-mparam.h"
+#include "mpn_extras.h"
+#include "tune.h"
+
+#undef FLINT_MPN_MULHIGH_K_TAB_SIZE
+#undef FLINT_MPN_MULHIGH_K_TAB
+#define TUNE_PROGRAM 1
+
+#define FLINT_MPN_MULHIGH_K_TAB_SIZE FLINT_MPN_MULHIGH_K_TAB_MAX_SIZE
+#define flint_mpn_mulhigh_k_tab flint_mpn_mulhigh_k_tab_0
+#define _flint_mpn_mulhigh_n_mulders_recursive _flint_mpn_mulhigh_n_mulders_recursive_0
+#define _flint_mpn_mulhigh_n_mulders _flint_mpn_mulhigh_n_mulders_0
+
+#include "mpn_extras/mulhigh.c"

src/tune/mpn_extras/tune_mulhigh_n.c

@@ -0,0 +1,37 @@
+/*
+    Copyright (C) 2024 Albin Ahlbäck
+
+    This file is part of FLINT.
+
+    FLINT is free software: you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
+*/
+
+#include "mpn_extras.h"
+#include "tune.h"
+
+#undef FLINT_MPN_MULHIGH_K_TAB_SIZE
+#define FLINT_MPN_MULHIGH_K_TAB_SIZE FLINT_MPN_MULHIGH_K_TAB_MAX_SIZE
+
+#define flint_mpn_mulhigh_k_tab flint_mpn_mulhigh_k_tab_0
+#define _flint_mpn_mulhigh_n_mulders _flint_mpn_mulhigh_n_mulders_0
+
+FLINT_DLL extern short flint_mpn_mulhigh_k_tab[FLINT_MPN_MULHIGH_K_TAB_SIZE];
+mp_limb_t _flint_mpn_mulhigh_n_mulders(mp_ptr, mp_srcptr, mp_srcptr, mp_size_t);
+
+/* IDEA:
+
+    1. Set all entries in flint_mpn_mulhigh_k_tab to zeroes.
+    2. Skip any further altering of those entries having a corresponding
+       hardcoded version.
+    3. When reasonable, check if basecase is faster.
+    4. The sequence of k should be weakly increasing. We only need to consider k
+       between n / 2 and n.
+       TODO: How can we prune the search with this information?
+    5. Run some warmups and run some hotlaps for each k. Only use the fastest
+       consistent time (see tune.c).
+    6. Use the k that corresponds to the fastest k and push that to
+       flint_mpn_mulhigh_k_tab so that it can be used in consecutive runs.
+*/

src/tune/tune.h

@@ -42,6 +42,10 @@ void n_param_clear(void *);
 double _tune_n_xgcd_0(void *);
 double _tune_n_xgcd_1(void *);
 
+/* mpn_extras ****************************************************************/
+
+#define FLINT_MPN_MULHIGH_K_TAB_MAX_SIZE 4096
+
 /* n_mod_vec *****************************************************************/
 #if WANT_N_MOD
 struct n_mod_vec_param_0