panfrost: split index cache into shared part

Split it into shared part since we're going to re-use it in lima.

Reviewed-by: Alyssa Rosenzweig <[email protected]>
Reviewed-by: Boris Brezillon <[email protected]>
Signed-off-by: Vasily Khoruzhick <[email protected]>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4051>

3 files changed, 178 insertions, 0 deletions

diff --git a/src/panfrost/shared/meson.build b/src/panfrost/shared/meson.build
index 9aae8e89a78..7f5f398c594 100644
--- a/src/panfrost/shared/meson.build
+++ b/src/panfrost/shared/meson.build
@@ -20,7 +20,10 @@
 # SOFTWARE.
 
 libpanfrost_shared_files = files(
+  'pan_minmax_cache.c',
   'pan_tiling.c',
+
+  'pan_minmax_cache.h',
   'pan_tiling.h',
 )
 
diff --git a/src/panfrost/shared/pan_minmax_cache.c b/src/panfrost/shared/pan_minmax_cache.c
new file mode 100644
index 00000000000..17018b28072
--- /dev/null
+++ b/src/panfrost/shared/pan_minmax_cache.c
@@ -0,0 +1,123 @@
+/*
+ * 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.
+ *
+ * Authors (Collabora):
+ *   Alyssa Rosenzweig <[email protected]>
+ */
+
+/* Index buffer min/max cache. We need to calculate the min/max for arbitrary
+ * slices (start, start + count) of the index buffer at drawtime. As this can
+ * be quite expensive, we cache. Conceptually, we just use a hash table mapping
+ * the key (start, count) to the value (min, max). In practice, mesa's hash
+ * table implementation is higher overhead than we would like and makes
+ * handling memory usage a little complicated. So we use this data structure
+ * instead. Searching is O(n) to the size, but the size is capped at the
+ * PANFROST_MINMAX_SIZE constant (so this is a tradeoff between cache hit/miss
+ * ratio and cache search speed). Note that keys are adjacent so we get cache
+ * line alignment benefits. Insertion is O(1) and in-order until the cache
+ * fills up, after that it evicts the oldest cached value in a ring facilitated
+ * by index.
+ */
+
+#include "pan_minmax_cache.h"
+
+bool
+panfrost_minmax_cache_get(struct panfrost_minmax_cache *cache, unsigned start, unsigned count,
+                     unsigned *min_index, unsigned *max_index)
+{
+        uint64_t ht_key = (((uint64_t)count) << 32) | start;
+        bool found = false;
+
+        if (!cache)
+           return false;
+
+        for (unsigned i = 0; i < cache->size; ++i) {
+                if (cache->keys[i] == ht_key) {
+                        uint64_t hit = cache->values[i];
+
+                        *min_index = hit & 0xffffffff;
+                        *max_index = hit >> 32;
+                        found = true;
+                        break;
+                }
+        }
+
+        return found;
+}
+
+void
+panfrost_minmax_cache_add(struct panfrost_minmax_cache *cache, unsigned start, unsigned count,
+                     unsigned min_index, unsigned max_index)
+{
+        uint64_t ht_key = (((uint64_t)count) << 32) | start;
+        uint64_t value = min_index | (((uint64_t)max_index) << 32);
+        unsigned index = 0;
+
+        if (!cache)
+                return;
+
+        if (cache->size == PANFROST_MINMAX_SIZE) {
+                index = cache->index++;
+                cache->index = cache->index % PANFROST_MINMAX_SIZE;
+        } else {
+                index = cache->size++;
+        }
+
+        cache->keys[index] =  ht_key;
+        cache->values[index] = value;
+
+}
+
+/* If we've been caching min/max indices and we update the index
+ * buffer, that may invalidate the min/max. Check what's been cached vs
+ * what we've written, and throw out invalid entries. */
+
+void
+panfrost_minmax_cache_invalidate(struct panfrost_minmax_cache *cache, struct pipe_transfer *transfer)
+{
+        /* Ensure there is a cache to invalidate and a write */
+        if (!cache)
+                return;
+
+        if (!(transfer->usage & PIPE_TRANSFER_WRITE))
+                return;
+
+        unsigned valid_count = 0;
+
+        for (unsigned i = 0; i < cache->size; ++i) {
+                uint64_t key = cache->keys[i];
+
+                uint32_t start = key & 0xffffffff;
+                uint32_t count = key >> 32;
+
+                /* 1D range intersection */
+                bool invalid = MAX2(transfer->box.x, start) < MIN2(transfer->box.x + transfer->box.width, start + count);
+                if (!invalid) {
+                        cache->keys[valid_count] = key;
+                        cache->values[valid_count] = cache->values[i];
+                        valid_count++;
+                }
+        }
+
+        cache->size = valid_count;
+        cache->index = 0;
+}
diff --git a/src/panfrost/shared/pan_minmax_cache.h b/src/panfrost/shared/pan_minmax_cache.h
new file mode 100644
index 00000000000..fe264370ef3
--- /dev/null
+++ b/src/panfrost/shared/pan_minmax_cache.h
@@ -0,0 +1,52 @@
+/*
+ * 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.
+ *
+ * Authors (Collabora):
+ *   Alyssa Rosenzweig <[email protected]>
+ */
+
+#ifndef H_PAN_MINMAX_CACHE
+#define H_PAN_MINMAX_CACHE
+
+#include "util/u_transfer.h"
+
+#define PANFROST_MINMAX_SIZE 64
+
+struct panfrost_minmax_cache {
+        uint64_t keys[PANFROST_MINMAX_SIZE];
+        uint64_t values[PANFROST_MINMAX_SIZE];
+        unsigned size;
+        unsigned index;
+};
+
+bool
+panfrost_minmax_cache_get(struct panfrost_minmax_cache *cache, unsigned start, unsigned count,
+                     unsigned *min_index, unsigned *max_index);
+
+void
+panfrost_minmax_cache_add(struct panfrost_minmax_cache *cache, unsigned start, unsigned count,
+                     unsigned min_index, unsigned max_index);
+
+void
+panfrost_minmax_cache_invalidate(struct panfrost_minmax_cache *cache, struct pipe_transfer *transfer);
+
+#endif