pvr: Handle special built-in variable loading in vertex shader

For now always allocate space for the special built-in variables
that need filling in for the vertex shader. Ideally we should get
the compiler to analyze the shader and tell the driver if they are
used so that we don't reserve and fill them needlessly.

Signed-off-by: Karmjit Mahil <Karmjit.Mahil@imgtec.com>
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21590>

diff --git a/src/imagination/vulkan/pvr_pipeline.c b/src/imagination/vulkan/pvr_pipeline.c
index 4f6ae8a..dac9152 100644 (file)
--- a/src/imagination/vulkan/pvr_pipeline.c
+++ b/src/imagination/vulkan/pvr_pipeline.c
@@ -455,6 +455,19 @@ static inline void pvr_pds_vertex_attrib_program_destroy(
 typedef struct pvr_pds_attrib_program (*const pvr_pds_attrib_programs_array_ptr)
    [PVR_PDS_VERTEX_ATTRIB_PROGRAM_COUNT];
 
+/* Indicates that the special variable is unused and has not been allocated a
+ * register.
+ */
+#define PVR_VERTEX_SPECIAL_VAR_UNUSED (-1)
+
+/* Each special variable gets allocated its own vtxin reg if used. */
+struct pvr_vertex_special_vars {
+   /* VertexIndex built-in. */
+   int16_t vertex_id_offset;
+   /* InstanceIndex built-in. */
+   int16_t instance_id_offset;
+};
+
 /* Generate and uploads a PDS program for DMAing vertex attribs into USC vertex
  * inputs. This will bake the code segment and create a template of the data
  * segment for the command buffer to fill in.
@@ -475,6 +488,7 @@ static VkResult pvr_pds_vertex_attrib_programs_create_and_upload(
    const struct pvr_pds_vertex_dma
       dma_descriptions[static const PVR_MAX_VERTEX_ATTRIB_DMAS],
    uint32_t dma_count,
+   const struct pvr_vertex_special_vars *special_vars_layout,
 
    pvr_pds_attrib_programs_array_ptr programs_out_ptr)
 {
@@ -496,6 +510,20 @@ static VkResult pvr_pds_vertex_attrib_programs_create_and_upload(
    } else {
       input.dma_list = dma_descriptions;
       input.dma_count = dma_count;
+
+      if (special_vars_layout->vertex_id_offset !=
+          PVR_VERTEX_SPECIAL_VAR_UNUSED) {
+         /* Gets filled by the HW and copied into the appropriate reg. */
+         input.flags = PVR_PDS_VERTEX_FLAGS_VERTEX_ID_REQUIRED;
+         input.vertex_id_register = special_vars_layout->vertex_id_offset;
+      }
+
+      if (special_vars_layout->instance_id_offset !=
+          PVR_VERTEX_SPECIAL_VAR_UNUSED) {
+         /* Gets filled by the HW and copied into the appropriate reg. */
+         input.flags = PVR_PDS_VERTEX_FLAGS_INSTANCE_ID_REQUIRED;
+         input.instance_id_register = special_vars_layout->instance_id_offset;
+      }
    }
 
    pvr_pds_setup_doutu(&input.usc_task_control,
@@ -504,30 +532,31 @@ static VkResult pvr_pds_vertex_attrib_programs_create_and_upload(
                        PVRX(PDSINST_DOUTU_SAMPLE_RATE_INSTANCE),
                        false);
 
-   /* TODO: If statements for all the "bRequired"s + ui32ExtraFlags. */
-
    /* Note: programs_out_ptr is a pointer to an array so this is fine. See the
     * typedef.
     */
    for (uint32_t i = 0; i < ARRAY_SIZE(*programs_out_ptr); i++) {
+      uint32_t extra_flags;
+
       switch (i) {
       case PVR_PDS_VERTEX_ATTRIB_PROGRAM_BASIC:
-         input.flags = 0;
+         extra_flags = 0;
          break;
 
       case PVR_PDS_VERTEX_ATTRIB_PROGRAM_BASE_INSTANCE:
-         input.flags = PVR_PDS_VERTEX_FLAGS_BASE_INSTANCE_VARIANT;
+         extra_flags = PVR_PDS_VERTEX_FLAGS_BASE_INSTANCE_VARIANT;
          break;
 
       case PVR_PDS_VERTEX_ATTRIB_PROGRAM_DRAW_INDIRECT:
-         /* We unset INSTANCE and set INDIRECT. */
-         input.flags = PVR_PDS_VERTEX_FLAGS_DRAW_INDIRECT_VARIANT;
+         extra_flags = PVR_PDS_VERTEX_FLAGS_DRAW_INDIRECT_VARIANT;
          break;
 
       default:
          unreachable("Invalid vertex attrib program type.");
       }
 
+      input.flags |= extra_flags;
+
       result =
          pvr_pds_vertex_attrib_program_create_and_upload(device,
                                                          allocator,
@@ -542,6 +571,8 @@ static VkResult pvr_pds_vertex_attrib_programs_create_and_upload(
 
          return result;
       }
+
+      input.flags &= ~extra_flags;
    }
 
    return VK_SUCCESS;
@@ -1813,6 +1844,32 @@ static void pvr_graphics_pipeline_alloc_vertex_inputs(
    *dma_count_out = dma_count;
 }
 
+static void pvr_graphics_pipeline_alloc_vertex_special_vars(
+   unsigned *num_vertex_input_regs,
+   struct pvr_vertex_special_vars *special_vars_layout_out)
+{
+   unsigned next_free_reg = *num_vertex_input_regs;
+   struct pvr_vertex_special_vars layout;
+
+   /* We don't support VK_KHR_shader_draw_parameters or Vulkan 1.1 so no
+    * BaseInstance, BaseVertex, DrawIndex.
+    */
+
+   /* TODO: The shader might not necessarily be using this so we'd just be
+    * wasting regs. Get the info from the compiler about whether or not the
+    * shader uses them and allocate them accordingly. For now we'll set them up
+    * regardless.
+    */
+
+   layout.vertex_id_offset = (int16_t)next_free_reg;
+   next_free_reg++;
+
+   layout.instance_id_offset = (int16_t)next_free_reg;
+   next_free_reg++;
+
+   *special_vars_layout_out = layout;
+}
+
 /* Compiles and uploads shaders and PDS programs. */
 static VkResult
 pvr_graphics_pipeline_compile(struct pvr_device *const device,
@@ -1851,6 +1908,11 @@ pvr_graphics_pipeline_compile(struct pvr_device *const device,
    rogue_vertex_inputs *vertex_input_layout;
    unsigned *vertex_input_reg_count;
 
+   /* TODO: The compiler should be making use of this to determine where
+    * specific special variables are located in the vtxin reg set.
+    */
+   struct pvr_vertex_special_vars special_vars_layout = { 0 };
+
    uint32_t sh_count[PVR_STAGE_ALLOCATION_COUNT] = { 0 };
 
    /* Setup shared build context. */
@@ -1868,6 +1930,9 @@ pvr_graphics_pipeline_compile(struct pvr_device *const device,
                                                 &vtx_dma_descriptions,
                                                 &vtx_dma_count);
 
+      pvr_graphics_pipeline_alloc_vertex_special_vars(vertex_input_reg_count,
+                                                      &special_vars_layout);
+
       for (enum pvr_stage_allocation pvr_stage =
               PVR_STAGE_ALLOCATION_VERTEX_GEOMETRY;
            pvr_stage < PVR_STAGE_ALLOCATION_COMPUTE;
@@ -2070,6 +2135,7 @@ pvr_graphics_pipeline_compile(struct pvr_device *const device,
       &ctx->stage_data.vs,
       vtx_dma_descriptions,
       vtx_dma_count,
+      &special_vars_layout,
       &gfx_pipeline->shader_state.vertex.pds_attrib_programs);
    if (result != VK_SUCCESS)
       goto err_free_frag_program;