[Mesa-dev] [PATCH] swr: fix transform feedback logic

[George Kyriazis]

The shader that is used to copy vertex data out of the vs/gs shaders to
the user-specified buffer (streamout os SO shader) was not using the
correct offsets.

Adjust the offsets that are used just for the SO shader:
- Make sure that position is handled in the same special way
  as in the vs/gs shaders
- Use the correct offset to be passed in the core
- consolidate register slot mapping logic into one function, since it's
  been calculated in 2 different places (one for calcuating the slot mask,
  and one for the register offsets themselves

Also make room for all attibutes in the backend vertex area.

Fixes:
- all vtk GL2PS tests
- 18 piglit tests (16 ext_transform_feedback tests,
  arb-quads-follow-provoking-vertex and primitive-type gl_points
---
 src/gallium/drivers/swr/swr_draw.cpp  | 11 ++++++++---
 src/gallium/drivers/swr/swr_state.cpp | 31 +++++++++++++++++++++++++++++--
 src/gallium/drivers/swr/swr_state.h   |  3 +++
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/swr/swr_draw.cpp b/src/gallium/drivers/swr/swr_draw.cpp
index 62ad3f7..218de0f 100644
--- a/src/gallium/drivers/swr/swr_draw.cpp
+++ b/src/gallium/drivers/swr/swr_draw.cpp
@@ -26,6 +26,7 @@
 #include "swr_resource.h"
 #include "swr_fence.h"
 #include "swr_query.h"
+#include "swr_state.h"
 #include "jit_api.h"
 
 #include "util/u_draw.h"
@@ -81,8 +82,11 @@ swr_draw_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
                offsets[output_buffer] = so->output[i].dst_offset;
             }
 
+            unsigned attrib_slot = so->output[i].register_index;
+            attrib_slot = swr_so_adjust_attrib(attrib_slot, ctx->vs);
+
             state.stream.decl[num].bufferIndex = output_buffer;
-            state.stream.decl[num].attribSlot = so->output[i].register_index - 1;
+            state.stream.decl[num].attribSlot = attrib_slot;
             state.stream.decl[num].componentMask =
                ((1 << so->output[i].num_components) - 1)
                << so->output[i].start_component;
@@ -130,9 +134,10 @@ swr_draw_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
    SWR_FRONTEND_STATE feState = {0};
 
    feState.vsVertexSize =
-      VERTEX_ATTRIB_START_SLOT +
+      VERTEX_ATTRIB_START_SLOT
       + ctx->vs->info.base.num_outputs
-      - (ctx->vs->info.base.writes_position ? 1 : 0);
+      - (ctx->vs->info.base.writes_position ? 1 : 0)
+      + ctx->fs->info.base.num_outputs;
 
    if (ctx->rasterizer->flatshade_first) {
       feState.provokingVertex = {1, 0, 0};
diff --git a/src/gallium/drivers/swr/swr_state.cpp b/src/gallium/drivers/swr/swr_state.cpp
index 501fdea..3e07929 100644
--- a/src/gallium/drivers/swr/swr_state.cpp
+++ b/src/gallium/drivers/swr/swr_state.cpp
@@ -345,13 +345,15 @@ swr_create_vs_state(struct pipe_context *pipe,
       // soState.streamToRasterizer not used
 
       for (uint32_t i = 0; i < stream_output->num_outputs; i++) {
+         unsigned attrib_slot = stream_output->output[i].register_index;
+         attrib_slot = swr_so_adjust_attrib(attrib_slot, swr_vs);
          swr_vs->soState.streamMasks[stream_output->output[i].stream] |=
-            1 << (stream_output->output[i].register_index - 1);
+            (1 << attrib_slot);
       }
       for (uint32_t i = 0; i < MAX_SO_STREAMS; i++) {
         swr_vs->soState.streamNumEntries[i] =
              _mm_popcnt_u32(swr_vs->soState.streamMasks[i]);
-        swr_vs->soState.vertexAttribOffset[i] = VERTEX_ATTRIB_START_SLOT; // TODO: optimize
+        swr_vs->soState.vertexAttribOffset[i] = 0;
        }
    }
 
@@ -1777,6 +1779,31 @@ swr_update_derived(struct pipe_context *pipe,
    ctx->dirty = post_update_dirty_flags;
 }
 
+unsigned
+swr_so_adjust_attrib(unsigned in_attrib,
+                     swr_vertex_shader *swr_vs)
+{
+   ubyte semantic_name;
+   unsigned attrib;
+
+   attrib = in_attrib + VERTEX_ATTRIB_START_SLOT;
+
+   if (swr_vs) {
+      semantic_name = swr_vs->info.base.output_semantic_name[in_attrib];
+      if (semantic_name == TGSI_SEMANTIC_POSITION) {
+         attrib = VERTEX_POSITION_SLOT;
+      } else {
+         for (int i = 0; i < PIPE_MAX_SHADER_OUTPUTS; i++) {
+            if (swr_vs->info.base.output_semantic_name[i] == TGSI_SEMANTIC_POSITION) {
+               attrib--;
+               break;
+            }
+         }
+      }
+   }
+
+   return attrib;
+}
 
 static struct pipe_stream_output_target *
 swr_create_so_target(struct pipe_context *pipe,
diff --git a/src/gallium/drivers/swr/swr_state.h b/src/gallium/drivers/swr/swr_state.h
index 7940a96..8cbd463 100644
--- a/src/gallium/drivers/swr/swr_state.h
+++ b/src/gallium/drivers/swr/swr_state.h
@@ -110,6 +110,9 @@ struct swr_derived_state {
 void swr_update_derived(struct pipe_context *,
                         const struct pipe_draw_info * = nullptr);
 
+unsigned swr_so_adjust_attrib(unsigned in_attrib,
+                              swr_vertex_shader *swr_vs);
+
 /*
  * Conversion functions: Convert mesa state defines to SWR.
  */
-- 
2.7.4