panvk/v10+: Implement nullDescriptor support

Adds support for nullDescriptors in PanVK by memsetting the relevant
descriptors to zero. This is valid for v9+.

Note that vertex/index buffers require special handling in order to rely
on out-of-bounds behavior.
For index buffers specifically, the approach is only valid for v10+, as
v9 does not have a way to specify index buffer size.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35609>

src/panfrost/vulkan/csf/panvk_vX_cmd_draw.c

@@ -311,7 +311,9 @@ prepare_vs_driver_set(struct panvk_cmd_buffer *cmdbuf,
             emit_vs_attrib(cmdbuf, i, vb_offset,
                            (struct mali_attribute_packed *)(&descs[i]));
          } else {
-            memset(&descs[i], 0, sizeof(descs[0]));
+            /* Write a NullDescriptor and rely on OOB behavior */
+            pan_cast_and_pack(&descs[i], NULL_DESCRIPTOR, cfg)
+               ;
          }
       }
 
@@ -326,15 +328,17 @@ prepare_vs_driver_set(struct panvk_cmd_buffer *cmdbuf,
 
       for (uint32_t i = 0; i < vb_count; i++) {
          const struct panvk_attrib_buf *vb = &cmdbuf->state.gfx.vb.bufs[i];
+         const bool nulldesc = (vb->address == 0 && vb->size == 0);
 
-         pan_cast_and_pack(&descs[vb_offset + i], BUFFER, cfg) {
-            if (vi->bindings_valid & BITFIELD_BIT(i)) {
+         if ((vi->bindings_valid & BITFIELD_BIT(i)) && !nulldesc) {
+            pan_cast_and_pack(&descs[vb_offset + i], BUFFER, cfg) {
                cfg.address = vb->address;
                cfg.size = vb->size;
-            } else {
-               cfg.address = 0;
-               cfg.size = 0;
             }
+         } else {
+            /* Write a NullDescriptor and rely on OOB behavior */
+            pan_cast_and_pack(&descs[vb_offset + i], NULL_DESCRIPTOR, cfg)
+               ;
          }
       }
 
@@ -2634,7 +2638,7 @@ panvk_per_arch(CmdDrawIndexedIndirect)(VkCommandBuffer commandBuffer,
    VK_FROM_HANDLE(panvk_cmd_buffer, cmdbuf, commandBuffer);
    VK_FROM_HANDLE(panvk_buffer, buffer, _buffer);
 
-   if (drawCount == 0 || cmdbuf->state.gfx.ib.size == 0)
+   if (drawCount == 0)
       return;
 
    struct panvk_draw_info draw = {
@@ -2687,7 +2691,7 @@ panvk_per_arch(CmdDrawIndexedIndirectCount)(VkCommandBuffer commandBuffer,
    VK_FROM_HANDLE(panvk_buffer, buffer, _buffer);
    VK_FROM_HANDLE(panvk_buffer, count_buffer, countBuffer);
 
-   if (maxDrawCount == 0 || cmdbuf->state.gfx.ib.size == 0)
+   if (maxDrawCount == 0)
       return;
 
    struct panvk_draw_info draw = {

src/panfrost/vulkan/panvk_vX_cmd_draw.c

@@ -872,10 +872,15 @@ panvk_per_arch(CmdBindVertexBuffers2)(VkCommandBuffer commandBuffer,
    for (uint32_t i = 0; i < bindingCount; i++) {
       VK_FROM_HANDLE(panvk_buffer, buffer, pBuffers[i]);
 
-      cmdbuf->state.gfx.vb.bufs[firstBinding + i].address =
-         panvk_buffer_gpu_ptr(buffer, pOffsets[i]);
-      cmdbuf->state.gfx.vb.bufs[firstBinding + i].size = panvk_buffer_range(
-         buffer, pOffsets[i], pSizes ? pSizes[i] : VK_WHOLE_SIZE);
+      if (buffer) {
+         cmdbuf->state.gfx.vb.bufs[firstBinding + i].address =
+            panvk_buffer_gpu_ptr(buffer, pOffsets[i]);
+         cmdbuf->state.gfx.vb.bufs[firstBinding + i].size = panvk_buffer_range(
+            buffer, pOffsets[i], pSizes ? pSizes[i] : VK_WHOLE_SIZE);
+      } else {
+         cmdbuf->state.gfx.vb.bufs[firstBinding + i].address = 0;
+         cmdbuf->state.gfx.vb.bufs[firstBinding + i].size = 0;
+      }
    }
 
    cmdbuf->state.gfx.vb.count =
@@ -899,15 +904,18 @@ panvk_per_arch(CmdBindIndexBuffer2)(VkCommandBuffer commandBuffer,
       cmdbuf->state.gfx.ib.host_addr =
          buf && buf->host_ptr ? buf->host_ptr + offset : NULL;
 #endif
-      cmdbuf->state.gfx.ib.index_size = vk_index_type_to_bytes(indexType);
    } else {
       cmdbuf->state.gfx.ib.size = 0;
-      cmdbuf->state.gfx.ib.dev_addr = 0;
+      /* In case of NullDescriptors, we need to set a non-NULL address and rely
+       * on out-of-bounds behavior against the zero size of the buffer. Note
+       * that this only works for v10+, as v9 does not have a way to specify the
+       * index buffer size. */
+      cmdbuf->state.gfx.ib.dev_addr = PAN_ARCH >= 10 ? 0x1000 : 0;
 #if PAN_ARCH < 9
       cmdbuf->state.gfx.ib.host_addr = 0;
 #endif
-      cmdbuf->state.gfx.ib.index_size = 0;
    }
+   cmdbuf->state.gfx.ib.index_size = vk_index_type_to_bytes(indexType);
 
    gfx_state_set_dirty(cmdbuf, IB);
 }

src/panfrost/vulkan/panvk_vX_descriptor_set.c

@@ -55,6 +55,20 @@ get_desc_slot_ptr(struct panvk_descriptor_set *set, uint32_t binding,
       memcpy(__dst, (desc), PANVK_DESCRIPTOR_SIZE);                            \
    } while (0)
 
+#if PAN_ARCH >= 9
+#define write_nulldesc(set, binding, elem, subdesc)                            \
+   do {                                                                        \
+      struct mali_null_descriptor_packed null_desc;                            \
+      pan_pack(&null_desc, NULL_DESCRIPTOR, cfg)                               \
+         ;                                                                     \
+      write_desc(set, binding, elem, &null_desc, (subdesc));                   \
+   } while (0)
+#else
+#define write_nulldesc(set, binding, elem, subdesc)                            \
+   do {                                                                        \
+   } while (0)
+#endif
+
 static void
 write_sampler_desc(struct panvk_descriptor_set *set,
                    const VkDescriptorImageInfo *const pImageInfo,
@@ -63,20 +77,25 @@ write_sampler_desc(struct panvk_descriptor_set *set,
    const struct panvk_descriptor_set_binding_layout *binding_layout =
       &set->layout->bindings[binding];
 
-   if (binding_layout->immutable_samplers && !write_immutable)
-      return;
-
    struct panvk_sampler *sampler;
 
    if (binding_layout->immutable_samplers) {
+      if (!write_immutable)
+         return;
       sampler = binding_layout->immutable_samplers[elem];
    } else {
-      sampler = panvk_sampler_from_handle(
-         pImageInfo ? pImageInfo->sampler : VK_NULL_HANDLE);
+      if (!pImageInfo)
+         return;
+      sampler = panvk_sampler_from_handle(pImageInfo->sampler);
    }
 
-   if (!sampler)
+   if (!sampler) {
+      for (uint8_t plane = 0; plane < binding_layout->samplers_per_desc;
+           plane++)
+         write_nulldesc(set, binding, elem,
+                        get_sampler_subdesc_info(binding_layout->type, plane));
       return;
+   }
 
    for (uint8_t plane = 0; plane < sampler->desc_count; plane++) {
       write_desc(set, binding, elem, &sampler->descs[plane],
@@ -89,26 +108,38 @@ write_image_view_desc(struct panvk_descriptor_set *set,
                       const VkDescriptorImageInfo *const pImageInfo,
                       uint32_t binding, uint32_t elem, VkDescriptorType type)
 {
-   if (pImageInfo && pImageInfo->imageView != VK_NULL_HANDLE) {
-      VK_FROM_HANDLE(panvk_image_view, view, pImageInfo->imageView);
+   if (!pImageInfo)
+      return;
 
-      uint8_t plane_count = vk_format_get_plane_count(view->vk.format);
-      for (uint8_t plane = 0; plane < plane_count; plane++) {
-         struct panvk_subdesc_info subdesc = get_tex_subdesc_info(type, plane);
+   const struct panvk_descriptor_set_binding_layout *binding_layout =
+      &set->layout->bindings[binding];
+
+   if (pImageInfo->imageView == VK_NULL_HANDLE) {
+      for (uint8_t plane = 0; plane < binding_layout->textures_per_desc;
+           plane++)
+         write_nulldesc(set, binding, elem,
+                        get_sampler_subdesc_info(binding_layout->type, plane));
+      return;
+   }
+
+   VK_FROM_HANDLE(panvk_image_view, view, pImageInfo->imageView);
+
+   uint8_t plane_count = vk_format_get_plane_count(view->vk.format);
+   for (uint8_t plane = 0; plane < plane_count; plane++) {
+      struct panvk_subdesc_info subdesc = get_tex_subdesc_info(type, plane);
 #if PAN_ARCH >= 9
-         if (type == VK_DESCRIPTOR_TYPE_STORAGE_IMAGE)
-            write_desc(set, binding, elem, &view->descs.storage_tex[plane],
-                       subdesc);
-         else
-            write_desc(set, binding, elem, &view->descs.tex[plane], subdesc);
+      if (type == VK_DESCRIPTOR_TYPE_STORAGE_IMAGE)
+         write_desc(set, binding, elem, &view->descs.storage_tex[plane],
+                    subdesc);
+      else
+         write_desc(set, binding, elem, &view->descs.tex[plane], subdesc);
 #else
-         if (type == VK_DESCRIPTOR_TYPE_STORAGE_IMAGE)
-            write_desc(set, binding, elem, &view->descs.img_attrib_buf,
-                       NO_SUBDESC);
-         else
-            write_desc(set, binding, elem, &view->descs.tex[plane], subdesc);
+      if (type == VK_DESCRIPTOR_TYPE_STORAGE_IMAGE)
+         write_desc(set, binding, elem, &view->descs.img_attrib_buf,
+                    NO_SUBDESC);
+      else
+         write_desc(set, binding, elem, &view->descs.tex[plane], subdesc);
 #endif
-      }
    }
 }
 
@@ -117,6 +148,11 @@ write_buffer_desc(struct panvk_descriptor_set *set,
                   const VkDescriptorBufferInfo *const info, uint32_t binding,
                   uint32_t elem, VkDescriptorType type)
 {
+   if (info->buffer == VK_NULL_HANDLE) {
+      write_nulldesc(set, binding, elem, NO_SUBDESC);
+      return;
+   }
+
    VK_FROM_HANDLE(panvk_buffer, buffer, info->buffer);
    const uint64_t range = panvk_buffer_range(buffer, info->offset, info->range);
    assert(range <= UINT32_MAX);
@@ -158,6 +194,11 @@ write_dynamic_buffer_desc(struct panvk_descriptor_set *set,
                           const VkDescriptorBufferInfo *const info,
                           uint32_t binding, uint32_t elem)
 {
+   if (info->buffer == VK_NULL_HANDLE) {
+      write_nulldesc(set, binding, elem, NO_SUBDESC);
+      return;
+   }
+
    VK_FROM_HANDLE(panvk_buffer, buffer, info->buffer);
    const struct panvk_descriptor_set_binding_layout *binding_layout =
       &set->layout->bindings[binding];
@@ -177,19 +218,21 @@ write_buffer_view_desc(struct panvk_descriptor_set *set,
                        const VkBufferView bufferView, uint32_t binding,
                        uint32_t elem, VkDescriptorType type)
 {
-   if (bufferView != VK_NULL_HANDLE) {
-      VK_FROM_HANDLE(panvk_buffer_view, view, bufferView);
+   if (bufferView == VK_NULL_HANDLE) {
+      write_nulldesc(set, binding, elem, NO_SUBDESC);
+      return;
+   }
+
+   VK_FROM_HANDLE(panvk_buffer_view, view, bufferView);
 
 #if PAN_ARCH < 9
-      if (type == VK_DESCRIPTOR_TYPE_STORAGE_TEXEL_BUFFER)
-         write_desc(set, binding, elem, &view->descs.img_attrib_buf,
-                    NO_SUBDESC);
-      else
-         write_desc(set, binding, elem, &view->descs.tex, NO_SUBDESC);
-#else
+   if (type == VK_DESCRIPTOR_TYPE_STORAGE_TEXEL_BUFFER)
+      write_desc(set, binding, elem, &view->descs.img_attrib_buf, NO_SUBDESC);
+   else
       write_desc(set, binding, elem, &view->descs.tex, NO_SUBDESC);
+#else
+   write_desc(set, binding, elem, &view->descs.tex, NO_SUBDESC);
 #endif
-   }
 }
 
 static void
@@ -340,6 +383,14 @@ desc_set_write_immutable_samplers(struct panvk_descriptor_set *set,
       for (uint32_t j = 0; j < array_size; j++) {
          struct panvk_sampler *sampler =
             layout->bindings[b].immutable_samplers[j];
+         if (!sampler) {
+            for (uint8_t plane = 0;
+                 plane < layout->bindings[b].samplers_per_desc; plane++)
+               write_nulldesc(
+                  set, b, j,
+                  get_sampler_subdesc_info(layout->bindings[b].type, plane));
+            continue;
+         }
          for (uint8_t plane = 0; plane < sampler->desc_count; plane++) {
             write_desc(set, b, j,
                        &sampler->descs[plane],