From 07a7d3627f5f888909a6b3f48d865171e7b4629a Mon Sep 17 00:00:00 2001
From: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Date: Thu, 13 Feb 2025 11:12:09 -0500
Subject: [PATCH] zink: store last index buffer

this allows skipping some draw-time ops when the same index buffer
is used repeatedly

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37318>
---
 src/gallium/drivers/zink/zink_context.c | 3 +++
 src/gallium/drivers/zink/zink_draw.cpp  | 9 ++++++---
 src/gallium/drivers/zink/zink_types.h   | 3 +++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/zink/zink_context.c b/src/gallium/drivers/zink/zink_context.c
index 5678f7da641..4073e229750 100644
--- a/src/gallium/drivers/zink/zink_context.c
+++ b/src/gallium/drivers/zink/zink_context.c
@@ -3726,6 +3726,7 @@ flush_batch(struct zink_context *ctx, bool sync)
       ctx->oom_stall = false;
       ctx->dd.bindless_bound = false;
       ctx->di.bindless_refs_dirty = true;
+      ctx->index_buffer = NULL;
       ctx->sample_locations_changed = ctx->gfx_pipeline_state.sample_locations_enabled;
       if (zink_screen(ctx->base.screen)->info.dynamic_state2_feats.extendedDynamicState2PatchControlPoints) {
          VKCTX(CmdSetPatchControlPointsEXT)(ctx->bs->cmdbuf, ctx->gfx_pipeline_state.dyn_state2.vertices_per_patch);
@@ -5346,6 +5347,8 @@ zink_context_replace_buffer_storage(struct pipe_context *pctx, struct pipe_resou
    unsigned rebind_count = num_rebinds ? rebind_buffer(ctx, d, rebind_mask, num_rebinds) : 0;
    if (rebind_count != d->bind_count[0] + d->bind_count[1])
       ctx->buffer_rebind_counter = p_atomic_inc_return(&screen->buffer_rebind_counter);
+   if (ctx->index_buffer == dst)
+      ctx->index_buffer = NULL;
 }
 
 static bool
diff --git a/src/gallium/drivers/zink/zink_draw.cpp b/src/gallium/drivers/zink/zink_draw.cpp
index 2a0be73d89f..6e944b3a584 100644
--- a/src/gallium/drivers/zink/zink_draw.cpp
+++ b/src/gallium/drivers/zink/zink_draw.cpp
@@ -387,12 +387,15 @@ zink_draw(struct pipe_context *pctx,
             zink_batch_reference_resource_move(ctx, zink_resource(index_buffer));
          else
             zink_batch_reference_resource(ctx, zink_resource(index_buffer));
-      } else {
-         index_buffer = dinfo->index.resource;
+      } else if (BATCH_CHANGED || ctx->index_buffer != dinfo->index.resource || ctx->index_size != dinfo->index_size) {
+         ctx->index_buffer = index_buffer = dinfo->index.resource;
+         ctx->index_size = dinfo->index_size;
          zink_batch_resource_usage_set(ctx->bs, zink_resource(index_buffer), false, true);
       }
       assert(index_size <= 4 && index_size != 3);
       assert(index_size != 1 || screen->info.have_EXT_index_type_uint8);
+   } else {
+      ctx->index_buffer = NULL;
    }
 
    ctx->was_line_loop = dinfo->was_line_loop;
@@ -503,7 +506,7 @@ zink_draw(struct pipe_context *pctx,
       zink_set_primitive_emulation_keys(ctx);
    }
 
-   if (index_size) {
+   if (index_buffer) {
       const VkIndexType index_type[3] = {
          VK_INDEX_TYPE_UINT8_EXT,
          VK_INDEX_TYPE_UINT16,
diff --git a/src/gallium/drivers/zink/zink_types.h b/src/gallium/drivers/zink/zink_types.h
index 48c29b77e3d..2f51a8a53ee 100644
--- a/src/gallium/drivers/zink/zink_types.h
+++ b/src/gallium/drivers/zink/zink_types.h
@@ -1925,6 +1925,9 @@ struct zink_context {
    uint32_t ds3_states;
    unsigned work_count;
 
+   struct pipe_resource *index_buffer; //last index buffer
+   unsigned index_size;
+
    uint32_t num_so_targets;
    struct pipe_stream_output_target *so_targets[PIPE_MAX_SO_BUFFERS];
    bool dirty_so_targets;