[Mesa-dev] [PATCH 5/5] i965: Use a uniform for gl_PatchVerticesIn in the TCS on Gen8+.

[Kenneth Graunke]

We still need to recompile the passthrough shader when this value
changes, as it also affects the output vertex count.  But otherwise,
we can eliminate recompiles on Gen8+.

We probably want to do this for Gen7 as well, but that requires
rewriting the input release code to use a loop, which is a trade-off
I'd need to consider in more detail.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/drivers/dri/i965/brw_context.c | 1 +
 src/mesa/drivers/dri/i965/brw_tcs.c     | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index aad2afb..cbe0693 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -599,6 +599,7 @@ brw_initialize_context_constants(struct brw_context *brw)
       ctx->Const.MaxClipPlanes = 8;
 
    ctx->Const.LowerTessLevel = true;
+   ctx->Const.LowerTCSPatchVerticesIn = brw->gen >= 8;
    ctx->Const.LowerTESPatchVerticesIn = true;
    ctx->Const.PrimitiveRestartForPatches = true;
 
diff --git a/src/mesa/drivers/dri/i965/brw_tcs.c b/src/mesa/drivers/dri/i965/brw_tcs.c
index 83fc157..e756b37 100644
--- a/src/mesa/drivers/dri/i965/brw_tcs.c
+++ b/src/mesa/drivers/dri/i965/brw_tcs.c
@@ -339,7 +339,8 @@ brw_upload_tcs_prog(struct brw_context *brw,
 
    memset(&key, 0, sizeof(key));
 
-   key.input_vertices = ctx->TessCtrlProgram.patch_vertices;
+   if (brw->gen < 8 || !tcp)
+      key.input_vertices = ctx->TessCtrlProgram.patch_vertices;
    key.outputs_written = per_vertex_slots;
    key.patch_outputs_written = per_patch_slots;
 
@@ -391,7 +392,8 @@ brw_tcs_precompile(struct gl_context *ctx,
    brw_setup_tex_for_precompile(brw, &key.tex, prog);
 
    /* Guess that the input and output patches have the same dimensionality. */
-   key.input_vertices = shader_prog->TessCtrl.VerticesOut;
+   if (brw->gen < 8)
+      key.input_vertices = shader_prog->TessCtrl.VerticesOut;
 
    key.tes_primitive_mode =
       shader_prog->_LinkedShaders[MESA_SHADER_TESS_EVAL] ?
-- 
2.8.3