[Mesa-dev] [PATCH] st/mesa: Don't record garbage streamout information in the non-SSO case.

[Kenneth Graunke]

In the non-SSO case, where multiple shader stages are linked together,
we were recording garbage pipe_stream_output_info structures for all
but the last enabled geometry-processing stage.

Specifically, we were using the gl_transform_feedback_info from
shader_program->last_vert_prog (the stage whose outputs will be
recorded)...but were pairing it with the output varying mappings
from the current shader stage.  For example, a program with a VS and
GS, the VS's pipe_shader_state would have a pipe_stream_output_info
based on the GS transform feedback info, but the VS output mapping.

This generally worked out okay because only the pipe_stream_output_info
for the last stage really matters - the others can be ignored.  However,
we'd like to avoid confusing the pipe driver.  In particular, my new
driver translates the stream out information to hardware packets at
bind_{vs,tes,gs}_state() time...and was hitting asserts about garbage
varyings that didn't exist.

This patch changes st/mesa to record a blank pipe_stream_output_info
with num_outputs = 0 for all stages prior to last_vert_prog.  The last
one is captured as normal.

(In the fully-SSO case, nothing should change - each program contains
a single shader stage, so last_vert_prog *is* the current shader.)

Tested with llvmpipe (piglit's gpu profile), and freedreno (a3xx,
gpu profile with -t transform.feedback).  Fixes several hundred CTS
tests on my new driver.
---
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 20 ++++++--------------
 src/mesa/state_tracker/st_glsl_to_tgsi.h   |  7 +------
 src/mesa/state_tracker/st_program.c        | 19 ++++++++-----------
 3 files changed, 15 insertions(+), 31 deletions(-)

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index dea91c7a189..19bd46d6097 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -7467,25 +7467,17 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
 }
 
 void
-st_translate_stream_output_info(glsl_to_tgsi_visitor *glsl_to_tgsi,
-                                const ubyte outputMapping[],
-                                struct pipe_stream_output_info *so)
-{
-   if (!glsl_to_tgsi->shader_program->last_vert_prog)
-      return;
-
-   struct gl_transform_feedback_info *info =
-      glsl_to_tgsi->shader_program->last_vert_prog->sh.LinkedTransformFeedback;
-   st_translate_stream_output_info2(info, outputMapping, so);
-}
-
-void
-st_translate_stream_output_info2(struct gl_transform_feedback_info *info,
+st_translate_stream_output_info(struct gl_transform_feedback_info *info,
                                 const ubyte outputMapping[],
                                 struct pipe_stream_output_info *so)
 {
    unsigned i;
 
+   if (!info) {
+      so->num_outputs = 0;
+      return;
+   }
+
    for (i = 0; i < info->NumOutputs; i++) {
       so->output[i].register_index =
          outputMapping[info->Outputs[i].OutputRegister];
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.h b/src/mesa/state_tracker/st_glsl_to_tgsi.h
index 8ccfff9bd37..fa6c0e02712 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.h
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.h
@@ -58,12 +58,7 @@ void free_glsl_to_tgsi_visitor(struct glsl_to_tgsi_visitor *v);
 GLboolean st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog);
 
 void
-st_translate_stream_output_info(struct glsl_to_tgsi_visitor *glsl_to_tgsi,
-                                const ubyte outputMapping[],
-                                struct pipe_stream_output_info *so);
-
-void
-st_translate_stream_output_info2(struct gl_transform_feedback_info *info,
+st_translate_stream_output_info(struct gl_transform_feedback_info *info,
                                 const ubyte outputMapping[],
                                 struct pipe_stream_output_info *so);
 
diff --git a/src/mesa/state_tracker/st_program.c b/src/mesa/state_tracker/st_program.c
index af86c47b945..3bc7b0649c4 100644
--- a/src/mesa/state_tracker/st_program.c
+++ b/src/mesa/state_tracker/st_program.c
@@ -458,12 +458,9 @@ st_translate_vertex_program(struct st_context *st,
    }
 
    if (stvp->shader_program) {
-      struct gl_program *prog = stvp->shader_program->last_vert_prog;
-      if (prog) {
-         st_translate_stream_output_info2(prog->sh.LinkedTransformFeedback,
-                                          stvp->result_to_output,
-                                          &stvp->tgsi.stream_output);
-      }
+      st_translate_stream_output_info(stvp->Base.sh.LinkedTransformFeedback,
+                                      stvp->result_to_output,
+                                      &stvp->tgsi.stream_output);
 
       st_store_ir_in_disk_cache(st, &stvp->Base, true);
       return true;
@@ -505,7 +502,7 @@ st_translate_vertex_program(struct st_context *st,
                                    output_semantic_name,
                                    output_semantic_index);
 
-      st_translate_stream_output_info(stvp->glsl_to_tgsi,
+      st_translate_stream_output_info(stvp->Base.sh.LinkedTransformFeedback,
                                       stvp->result_to_output,
                                       &stvp->tgsi.stream_output);
 
@@ -1417,7 +1414,7 @@ st_translate_program_common(struct st_context *st,
    }
    ureg_destroy(ureg);
 
-   st_translate_stream_output_info(glsl_to_tgsi,
+   st_translate_stream_output_info(prog->sh.LinkedTransformFeedback,
                                    outputMapping,
                                    &out_state->stream_output);
 
@@ -1464,9 +1461,9 @@ st_translate_program_stream_output(struct gl_program *prog,
       }
    }
 
-   st_translate_stream_output_info2(prog->sh.LinkedTransformFeedback,
-                                    outputMapping,
-                                    stream_output);
+   st_translate_stream_output_info(prog->sh.LinkedTransformFeedback,
+                                   outputMapping,
+                                   stream_output);
 }
 
 /**
-- 
2.19.0