panfrost: Add rectangle subtraction algorithm

For better supporting KHR_partial_update.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5929>

src/gallium/drivers/panfrost/meson.build

@@ -40,6 +40,7 @@ files_panfrost = files(
   'pan_fragment.c',
   'pan_sfbd.c',
   'pan_mfbd.c',
+  'pan_partial_update.c',
 )
 
 panfrost_includes = [

src/gallium/drivers/panfrost/pan_partial_update.c

@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2020 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+#include "util/ralloc.h"
+#include "pan_partial_update.h"
+
+static struct pan_rect
+pan_make_rect(unsigned minx, unsigned miny, unsigned maxx, unsigned maxy)
+{
+        struct pan_rect r = {
+                .minx = minx,
+                .miny = miny,
+                .maxx = maxx,
+                .maxy = maxy
+        };
+
+        return r;
+}
+
+static struct pan_rect
+pan_from_pipe(const struct pipe_box *p)
+{
+        return pan_make_rect(p->x, p->y, p->x + p->width, p->y + p->height);
+}
+
+/* Helper to clip a rect inside another box */
+
+static struct pan_rect
+pan_clip_rect(
+        const struct pan_rect *r,
+        const struct pan_rect *clip)
+{
+        unsigned minx = MAX2(r->minx, clip->minx);
+        unsigned miny = MAX2(r->miny, clip->miny);
+        unsigned maxx = MAX2(MIN2(r->maxx, clip->maxx), minx);
+        unsigned maxy = MAX2(MIN2(r->maxy, clip->maxy), miny);
+
+        return pan_make_rect(minx, miny, maxx, maxy);
+}
+
+/* Subtract d from r, yielding four (possibly degenerate) rectangles for each
+ * bounding region */
+
+static void
+pan_subtract_from_rect(
+                struct pan_rect *out,
+                const struct pan_rect *r,
+                const struct pan_rect *d)
+{
+        struct pan_rect dc = pan_clip_rect(r, d);
+
+        out[0] = pan_make_rect(r->minx, r->miny, dc.minx, r->maxy);
+        out[1] = pan_make_rect(dc.minx, r->miny, dc.maxx, dc.miny);
+        out[2] = pan_make_rect(dc.maxx, r->miny, r->maxx, r->maxy);
+        out[3] = pan_make_rect(dc.minx, dc.maxy, dc.maxx, r->maxy);
+}
+
+/* Subtract d from the set of rects R, returning the number of
+ * (non-degenerate) rectangles returned.
+ *
+ * out must be at least sizeof(struct pan_rect) * R_len * 4 bytes
+ *
+ * Trivially satisfies: return value < (R_len * 4) */
+
+static unsigned
+pan_subtract_from_rects(
+                struct pan_rect *out,
+                const struct pan_rect *R,
+                unsigned R_len,
+                const struct pan_rect *d)
+{
+        unsigned count = 0;
+        struct pan_rect temp[4];
+
+        for (unsigned r = 0; r < R_len; ++r) {
+                pan_subtract_from_rect(temp, &R[r], d);
+
+                /* Copy the rectangles with nonzero area */
+                for (unsigned i = 0; i < 4; ++i) {
+                        if (temp[i].maxx <= temp[i].minx) continue;
+                        if (temp[i].maxy <= temp[i].miny) continue;
+
+                        out[count++] = temp[i];
+                }
+        }
+
+        return count;
+}
+
+struct pan_rect *
+pan_subtract_damage(
+                void *memctx,
+                unsigned initial_w, unsigned initial_h,
+                unsigned nrects,
+                const struct pipe_box *rects,
+                unsigned *out_len)
+{
+        struct pan_rect *R = ralloc(memctx, struct pan_rect);
+        *R = pan_make_rect(0, 0, initial_w, initial_h);
+        unsigned R_len = 1;
+
+        for (unsigned d = 0; d < nrects; ++d) {
+                const struct pan_rect D = pan_from_pipe(&rects[d]);
+                struct pan_rect *out = rzalloc_array(memctx, struct pan_rect,
+                        R_len * 4);
+
+                R_len = pan_subtract_from_rects(out, R, R_len, &D);
+                ralloc_free(R);
+                R = out;
+        }
+
+        *out_len = R_len;
+        return R;
+}

src/gallium/drivers/panfrost/pan_partial_update.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2019 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Authors (Collabora):
+ *   Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
+ *
+ */
+
+#ifndef __PAN_PARTIAL_UPDATE_H
+#define __PAN_PARTIAL_UPDATE_H
+
+#include "pipe/p_state.h"
+
+/* Like pipe_box but in terms of maxx/maxy instead of w/h, which is much easier
+ * to work with for our purposes */
+
+struct pan_rect {
+        unsigned minx, miny;
+        unsigned maxx, maxy;
+};
+
+struct pan_rect *
+pan_subtract_damage(
+                void *memctx,
+                unsigned initial_w, unsigned initial_h,
+                unsigned nrects,
+                const struct pipe_box *rects,
+                unsigned *R_len);
+
+#endif

src/gallium/drivers/panfrost/pan_resource.c

@@ -499,6 +499,14 @@ panfrost_resource_set_damage_region(struct pipe_screen *screen,
                 damage_extent->maxy = MAX2(damage_extent->maxy,
                                            MIN2(y + h, res->height0));
         }
+
+        if (nrects == 0) {
+                damage_extent->minx = 0;
+                damage_extent->miny = 0;
+                damage_extent->maxx = res->width0;
+                damage_extent->maxy = res->height0;
+        }
+
 }
 
 static struct pipe_resource *