iqk_mul_mat: better srategy when nrc_y not divisible by ny (#71)

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>

Author: ikawrakow

ggml/src/iqk/iqk_mul_mat.cpp

@@ -107,16 +107,39 @@ struct MulMat {
         while (!funcs[ny-1] && ny > 0) --ny;
         int n_step = (nrc_y - info.cur_y)/ny;
         if (n_step > 0) {
-            for (int ix = 0; ix < nrc_x; ix += k_x_step) {
-                auto this_info = info;
-                this_info.s += ix;
-                int this_nrc_x = ix + k_x_step <= nrc_x ? k_x_step : nrc_x - ix;
-                for (int iy = 0; iy < n_step; ++iy) {
-                    funcs[ny-1](n, (const void *)((const char *)vx + ix*bx), bx, this_info, this_nrc_x);
-                    this_info.cur_y += ny;
+            if (n_step*ny != nrc_y) {
+                ++n_step;
+                int ny1 = nrc_y/n_step;
+                int ny2 = ny1 + 1;
+                int my1 = n_step*ny2 - nrc_y;
+                int my2 = n_step - my1;
+                for (int ix = 0; ix < nrc_x; ix += k_x_step) {
+                    auto this_info = info;
+                    this_info.s += ix;
+                    int this_nrc_x = ix + k_x_step <= nrc_x ? k_x_step : nrc_x - ix;
+                    for (int iy = 0; iy < my1; ++iy) {
+                        funcs[ny1-1](n, (const void *)((const char *)vx + ix*bx), bx, this_info, this_nrc_x);
+                        this_info.cur_y += ny1;
+                    }
+                    for (int iy = 0; iy < my2; ++iy) {
+                        funcs[ny2-1](n, (const void *)((const char *)vx + ix*bx), bx, this_info, this_nrc_x);
+                        this_info.cur_y += ny2;
+                    }
+                }
+                info.cur_y += nrc_y;
+            }
+            else {
+                for (int ix = 0; ix < nrc_x; ix += k_x_step) {
+                    auto this_info = info;
+                    this_info.s += ix;
+                    int this_nrc_x = ix + k_x_step <= nrc_x ? k_x_step : nrc_x - ix;
+                    for (int iy = 0; iy < n_step; ++iy) {
+                        funcs[ny-1](n, (const void *)((const char *)vx + ix*bx), bx, this_info, this_nrc_x);
+                        this_info.cur_y += ny;
+                    }
                 }
+                info.cur_y += ny * n_step;
             }
-            info.cur_y += ny * n_step;
         }
         int n_left = nrc_y - info.cur_y;
         if (n_left > 0) {