[Mesa-dev] [PATCH v6 2/2] anv: enable VK_EXT_shader_stencil_export

[Caio Marcelo de Oliveira Filho]

From: Gustavo Lima Chaves <gustavo.lima.chaves at intel.com>

v2:
An attempt to support SpvExecutionModeStencilRefReplacingEXT's behavior
also follows, with the interpretation to said mode being we prevent
writes to the built-in FragStencilRefEXT variable when the execution
mode isn't set.

v3:
A more cautious reading of 1db44252d01bf7539452ccc2b5210c74b8dcd573 led
me to a missing change that would stop (what I later discovered were)
GPU hangs on the CTS test written to exercize this.

v4:
Turn FragStencilRefEXT decoration usage without StencilRefReplacingEXT
mode into a warning, instead of trying to make the variable read-only.
If we are to follow the originating extension on GL, the built-in
variable in question should never be readable anyway.
---

This is the original patch from Gustavo Lima Chaves (v5 was another
rebase), with some trivial changes to rebase.

I'm updating the test on Vulkan CTS to make sure we have some coverage
of this feature; so this should only land once that gets accepted, but
is ready for review.

 src/compiler/shader_info.h         | 2 ++
 src/compiler/spirv/spirv_to_nir.c  | 4 ++++
 src/compiler/spirv/vtn_variables.c | 5 +++++
 src/intel/vulkan/anv_extensions.py | 1 +
 src/intel/vulkan/anv_pipeline.c    | 1 +
 src/intel/vulkan/genX_pipeline.c   | 1 +
 6 files changed, 14 insertions(+)

diff --git a/src/compiler/shader_info.h b/src/compiler/shader_info.h
index 81f844d36ae..e9141261e8b 100644
--- a/src/compiler/shader_info.h
+++ b/src/compiler/shader_info.h
@@ -180,6 +180,8 @@ typedef struct shader_info {
 
          bool pixel_center_integer;
 
+         bool outputs_stencil;
+
          /** gl_FragDepth layout for ARB_conservative_depth. */
          enum gl_frag_depth_layout depth_layout;
       } fs;
diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 6c0551603ea..81c5e890071 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -3577,6 +3577,10 @@ vtn_handle_execution_mode(struct vtn_builder *b, struct vtn_value *entry_point,
    case SpvExecutionModeContractionOff:
       break; /* OpenCL */
 
+   case SpvExecutionModeStencilRefReplacingEXT:
+      b->shader->info.fs.outputs_stencil = true;
+      break;
+
    default:
       vtn_fail("Unhandled execution mode");
    }
diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index 53bee1b9288..0a3108bdc43 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -1429,6 +1429,11 @@ apply_var_decoration(struct vtn_builder *b, nir_variable *nir_var,
       case SpvBuiltInSamplePosition:
          nir_var->data.origin_upper_left = b->origin_upper_left;
          break;
+      case SpvBuiltInFragStencilRefEXT:
+         if (!b->shader->info.fs.outputs_stencil)
+            vtn_warn("The StencilRefReplacingEXT mode should be declared when"
+                     " the decoration FragStencilRefEXT is used on a variable");
+         break;
       default:
          break;
       }
diff --git a/src/intel/vulkan/anv_extensions.py b/src/intel/vulkan/anv_extensions.py
index b5bee0881ce..8160864685f 100644
--- a/src/intel/vulkan/anv_extensions.py
+++ b/src/intel/vulkan/anv_extensions.py
@@ -112,6 +112,7 @@ EXTENSIONS = [
     Extension('VK_EXT_global_priority',                   1,
               'device->has_context_priority'),
     Extension('VK_EXT_shader_viewport_index_layer',       1, True),
+    Extension('VK_EXT_shader_stencil_export',             1, 'device->info.gen >= 9'),
 ]
 
 class VkVersion:
diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 8f30136b100..c37b9b96e11 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -152,6 +152,7 @@ anv_shader_compile_to_nir(struct anv_pipeline *pipeline,
          .subgroup_quad = true,
          .subgroup_shuffle = true,
          .subgroup_vote = true,
+         .stencil_export = true,
       },
    };
 
diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 6016d257584..462c59451cc 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -1600,6 +1600,7 @@ emit_3dstate_ps_extra(struct anv_pipeline *pipeline,
          ps.PixelShaderHasUAV = true;
 
 #if GEN_GEN >= 9
+      ps.PixelShaderComputesStencil = wm_prog_data->computed_stencil;
       ps.PixelShaderPullsBary    = wm_prog_data->pulls_bary;
       ps.InputCoverageMaskState  = wm_prog_data->uses_sample_mask ?
                                    ICMS_INNER_CONSERVATIVE : ICMS_NONE;
-- 
2.17.0