i965: Add scalar geometry shader support.

This is hidden behind INTEL_SCALAR_GS=1 for now, as we don't yet support
instanced geometry shaders, and Orbital Explorer's shader spills like
crazy.  But the infrastructure is in place, and it's largely working.

v2: Lots of rebasing.

v3: (feedback from Kristian Høgsberg)
- Handle stride and subreg_offset correctly for ATTRs; use a helper.
- Fix missing emit_shader_time_end() call.
- Delete dead code after early EOT in static vertex case to avoid
  tripping asserts in emit_shader_time_end().
- Use proper D/UD type in intexp2().
- Fix "EndPrimitve" and "to that" typos.
- Assert that invocations == 1 so we know this is missing.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
index cfb5cd9..49c1083 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
@@ -29,6 +29,7 @@
 
 #include "brw_vec4_gs_visitor.h"
 #include "gen6_gs_visitor.h"
+#include "brw_fs.h"
 
 namespace brw {
 
@@ -812,6 +813,30 @@ brw_compile_gs(const struct brw_compiler *compiler, void *log_data,
     * program.
     */
 
+   if (compiler->scalar_gs) {
+      /* TODO: Support instanced GS.  We have basically no tests... */
+      assert(prog_data->invocations == 1);
+
+      fs_visitor v(compiler, log_data, mem_ctx, &c, prog_data, shader,
+                   shader_time_index);
+      if (v.run_gs()) {
+         prog_data->base.dispatch_mode = DISPATCH_MODE_SIMD8;
+
+         fs_generator g(compiler, log_data, mem_ctx, &c.key,
+                        &prog_data->base.base, v.promoted_constants,
+                        false, "GS");
+         if (unlikely(INTEL_DEBUG & DEBUG_GS)) {
+            const char *label =
+               shader->info.label ? shader->info.label : "unnamed";
+            char *name = ralloc_asprintf(mem_ctx, "%s geometry shader %s",
+                                         label, shader->info.name);
+            g.enable_debug(name);
+         }
+         g.generate_code(v.cfg, 8);
+         return g.get_assembly(final_assembly_size);
+      }
+   }
+
    if (compiler->devinfo->gen >= 7) {
       /* Compile the geometry shader in DUAL_OBJECT dispatch mode, if we can do
        * so without spilling. If the GS invocations count > 1, then we can't use