[Mesa-dev] [PATCH v2] anv: always allocate a vertex element with vertexid or instanceid

[Lionel Landwerlin]

Up to now on Gen8+ we only allocated a vertex element for
gl_InstanceIndex or gl_VertexIndex when a vertex shader uses
gl_BaseInstanceARB or gl_BaseVertexARB. This is because we would
configure the VF_SGVS packet to make the VF unit write the
gl_InstanceIndex & gl_VertexIndex values right behind the values
computed from the vertex buffers.

In the next commit we will also write the gl_DrawIDARB value. Our
backend expects to pull the gl_DrawIDARB value from the element
following the element containing gl_InstanceIndex, gl_VertexIndex,
gl_BaseInstanceARB and gl_BaseVertexARB (see
vec4_vs_visitor::setup_attributes). Therefore we need to allocate an
element for the SGVS elements as long as at least one of the SGVS
element is read by the shader. Otherwise our shader will use a
gl_DrawIDARB value pulled from the URB one element too far (most
likely garbage).

v2: Fix my english (Lionel)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 src/intel/vulkan/genX_pipeline.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 9629ca9bf9..4c1afd0319 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -94,22 +94,10 @@ emit_vertex_input(struct anv_pipeline *pipeline,
    assert((inputs_read & ((1 << VERT_ATTRIB_GENERIC0) - 1)) == 0);
    const uint32_t elements = inputs_read >> VERT_ATTRIB_GENERIC0;
    const uint32_t elements_double = double_inputs_read >> VERT_ATTRIB_GENERIC0;
-
-#if GEN_GEN >= 8
-   /* On BDW+, we only need to allocate space for base ids.  Setting up
-    * the actual vertex and instance id is a separate packet.
-    */
-   const bool needs_svgs_elem = vs_prog_data->uses_basevertex ||
-                                vs_prog_data->uses_baseinstance;
-#else
-   /* On Haswell and prior, vertex and instance id are created by using the
-    * ComponentControl fields, so we need an element for any of them.
-    */
    const bool needs_svgs_elem = vs_prog_data->uses_vertexid ||
                                 vs_prog_data->uses_instanceid ||
                                 vs_prog_data->uses_basevertex ||
                                 vs_prog_data->uses_baseinstance;
-#endif

    uint32_t elem_count = __builtin_popcount(elements) -
       __builtin_popcount(elements_double) / 2;
--
2.11.0