radv: switch to on-demand PS epilogs for GPL

RADV currently has two paths for PS epilogs:
- the first one is mostly used by GPL to compile fragment shader epilogs
  as part of the graphics pipeline. It's supposed to be optimal because
  fragment shader epilogs are compiled in the pipeline and eventually
  cached.
- the second one (the "on-demand" path) is required when some dynamic
  states are used because otherwise it's just impossible to compile the
  fragment shader. These epilogs are compiled during cmdbuf recording
  when all needed info are known, they are also cached in memory. This
  is the main path for Zink.

Having two different paths isn't ideal for maintenance but there is
another problem. On RDNA3, alpha to coverage needs to be exported as
part of MRTZ when either depth/stencil/samplemask are exported. The
problem being that with GPL, the PSO multisample state can be NULL when
the frag shader lib is created, which means that we can't know if atc
needs to be exported or not, even if it's static. The solution seems to
to always use on-demand fragment shader epilogs for GPL on RDNA3.

So far, I think that switching to on-demand PS epilogs unconditionally
for GPL shouldn't hurt performance and that will simplify a lot of
things.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26398>

src/amd/vulkan/radv_device.c

@@ -823,8 +823,10 @@ radv_CreateDevice(VkPhysicalDevice physicalDevice, const VkDeviceCreateInfo *pCr
       }
       case VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_GRAPHICS_PIPELINE_LIBRARY_FEATURES_EXT: {
          const VkPhysicalDeviceGraphicsPipelineLibraryFeaturesEXT *features = (const void *)ext;
-         if (features->graphicsPipelineLibrary)
+         if (features->graphicsPipelineLibrary) {
             vs_prologs = true;
+            ps_epilogs = true;
+         }
          break;
       }
       case VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTENDED_DYNAMIC_STATE_3_FEATURES_EXT: {

src/amd/vulkan/radv_pipeline_graphics.c

@@ -261,21 +261,32 @@ radv_format_meta_fs_key(struct radv_device *device, VkFormat format)
 }
 
 static bool
-radv_pipeline_needs_dynamic_ps_epilog(const struct radv_graphics_pipeline *pipeline)
+radv_pipeline_needs_dynamic_ps_epilog(const struct radv_graphics_pipeline *pipeline,
+                                      VkGraphicsPipelineLibraryFlagBitsEXT lib_flags)
 {
+   /* Use a PS epilog when the fragment shader is compiled without the fragment output interface. */
+   if ((pipeline->active_stages & VK_SHADER_STAGE_FRAGMENT_BIT) &&
+       (lib_flags & VK_GRAPHICS_PIPELINE_LIBRARY_FRAGMENT_SHADER_BIT_EXT) &&
+       !(lib_flags & VK_GRAPHICS_PIPELINE_LIBRARY_FRAGMENT_OUTPUT_INTERFACE_BIT_EXT))
+      return true;
+
    /* These dynamic states need to compile PS epilogs on-demand. */
-   return !!(pipeline->dynamic_states & (RADV_DYNAMIC_COLOR_BLEND_ENABLE | RADV_DYNAMIC_COLOR_WRITE_MASK |
-                                         RADV_DYNAMIC_ALPHA_TO_COVERAGE_ENABLE | RADV_DYNAMIC_COLOR_BLEND_EQUATION));
+   if (pipeline->dynamic_states & (RADV_DYNAMIC_COLOR_BLEND_ENABLE | RADV_DYNAMIC_COLOR_WRITE_MASK |
+                                   RADV_DYNAMIC_ALPHA_TO_COVERAGE_ENABLE | RADV_DYNAMIC_COLOR_BLEND_EQUATION))
+      return true;
+
+   return false;
 }
 
 static struct radv_blend_state
-radv_pipeline_init_blend_state(struct radv_graphics_pipeline *pipeline, const struct vk_graphics_pipeline_state *state)
+radv_pipeline_init_blend_state(struct radv_graphics_pipeline *pipeline, const struct vk_graphics_pipeline_state *state,
+                               VkGraphicsPipelineLibraryFlagBitsEXT lib_flags)
 {
    const struct radv_shader *ps = pipeline->base.shaders[MESA_SHADER_FRAGMENT];
    struct radv_blend_state blend = {0};
    unsigned spi_shader_col_format = 0;
 
-   if (radv_pipeline_needs_dynamic_ps_epilog(pipeline))
+   if (radv_pipeline_needs_dynamic_ps_epilog(pipeline, lib_flags))
       return blend;
 
    if (ps) {
@@ -1920,7 +1931,7 @@ radv_generate_graphics_pipeline_key(const struct radv_device *device, const stru
    if (device->primitives_generated_query)
       key.primitives_generated_query = true;
 
-   if (radv_pipeline_needs_dynamic_ps_epilog(pipeline))
+   if (radv_pipeline_needs_dynamic_ps_epilog(pipeline, lib_flags))
       key.ps.dynamic_ps_epilog = true;
 
    /* The fragment shader needs an epilog when both:
@@ -2450,7 +2461,7 @@ radv_skip_graphics_pipeline_compile(const struct radv_device *device, const stru
       return false;
 
    /* Do not skip when the PS epilog needs to be compiled. */
-   if (!radv_pipeline_needs_dynamic_ps_epilog(pipeline) && pipeline->base.shaders[MESA_SHADER_FRAGMENT] &&
+   if (!radv_pipeline_needs_dynamic_ps_epilog(pipeline, lib_flags) && pipeline->base.shaders[MESA_SHADER_FRAGMENT] &&
        pipeline->base.shaders[MESA_SHADER_FRAGMENT]->info.has_epilog && !pipeline->ps_epilog)
       return false;
 
@@ -3991,7 +4002,7 @@ radv_graphics_pipeline_init(struct radv_graphics_pipeline *pipeline, struct radv
       radv_pipeline_init_input_assembly_state(device, pipeline);
    radv_pipeline_init_dynamic_state(device, pipeline, &state, pCreateInfo);
 
-   struct radv_blend_state blend = radv_pipeline_init_blend_state(pipeline, &state);
+   struct radv_blend_state blend = radv_pipeline_init_blend_state(pipeline, &state, needed_lib_flags);
 
    /* Copy the non-compacted SPI_SHADER_COL_FORMAT which is used to emit RBPLUS state. */
    pipeline->col_format_non_compacted = blend.spi_shader_col_format;