compiler,nir: Gather needs_full_quad_helper_invocations info

This is needed on Qualcomm, where there are separate fields to enable
just 3 fragments and all 4 fragments.

Reviewed-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Reviewed-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Fixes: 264d8a6766 ("ir3: Set need_full_quad depending on info.fs.require_full_quads")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33862>

src/compiler/nir/nir_gather_info.c

@@ -827,14 +827,26 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader,
          shader->info.writes_memory = true;
 
       if (nir_intrinsic_has_semantic(instr, NIR_INTRINSIC_QUADGROUP)) {
-         if (shader->info.stage == MESA_SHADER_FRAGMENT)
+         if (shader->info.stage == MESA_SHADER_FRAGMENT) {
             shader->info.fs.needs_coarse_quad_helper_invocations = true;
+            /* For now assume that plain ddx/ddy are always coarse. This is
+             * true for most backends.
+             * TODO: Switch ddx to ddx_coarse for remaining backends.
+             */
+            if (instr->intrinsic != nir_intrinsic_ddx &&
+                instr->intrinsic != nir_intrinsic_ddy &&
+                instr->intrinsic != nir_intrinsic_ddx_coarse &&
+                instr->intrinsic != nir_intrinsic_ddy_coarse)
+               shader->info.fs.needs_full_quad_helper_invocations = true;
+         }
       } else if (nir_intrinsic_has_semantic(instr, NIR_INTRINSIC_SUBGROUP)) {
          shader->info.uses_wide_subgroup_intrinsics = true;
 
          if (shader->info.stage == MESA_SHADER_FRAGMENT &&
-             shader->info.fs.require_full_quads)
+             shader->info.fs.require_full_quads) {
             shader->info.fs.needs_coarse_quad_helper_invocations = true;
+            shader->info.fs.needs_full_quad_helper_invocations = true;
+         }
       }
 
       if (instr->intrinsic == nir_intrinsic_image_levels ||
@@ -854,6 +866,10 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader,
 static void
 gather_tex_info(nir_tex_instr *instr, nir_shader *shader)
 {
+   /* For now we assume that implicit derivatives use coarse derivatives.
+    * Drivers that need to assume otherwise might have to plumb through a
+    * property.
+    */
    if (shader->info.stage == MESA_SHADER_FRAGMENT &&
        nir_tex_instr_has_implicit_derivative(instr))
       shader->info.fs.needs_coarse_quad_helper_invocations = true;
@@ -998,6 +1014,7 @@ nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint)
       shader->info.fs.color_is_dual_source = false;
       shader->info.fs.uses_fbfetch_output = false;
       shader->info.fs.needs_coarse_quad_helper_invocations = false;
+      shader->info.fs.needs_full_quad_helper_invocations = false;
    }
    if (shader->info.stage == MESA_SHADER_TESS_CTRL) {
       shader->info.tess.tcs_same_invocation_inputs_read = 0;

src/compiler/nir/nir_print.c

@@ -2703,6 +2703,7 @@ print_shader_info(const struct shader_info *info, FILE *fp)
 
       print_nz_bool(fp, "require_full_quads", info->fs.require_full_quads);
       print_nz_bool(fp, "needs_coarse_quad_helper_invocations", info->fs.needs_coarse_quad_helper_invocations);
+      print_nz_bool(fp, "needs_full_quad_helper_invocations", info->fs.needs_full_quad_helper_invocations);
       print_nz_bool(fp, "uses_sample_qualifier", info->fs.uses_sample_qualifier);
       print_nz_bool(fp, "uses_sample_shading", info->fs.uses_sample_shading);
       print_nz_bool(fp, "early_fragment_tests", info->fs.early_fragment_tests);

src/compiler/shader_info.h

@@ -365,6 +365,15 @@ typedef struct shader_info {
           */
          bool needs_coarse_quad_helper_invocations:1;
 
+         /**
+          * True if this fragment shader requires helper invocations for all
+          * four fragments in the quad. This can be caused by all the same
+          * things as needs_coarse_quad_helper_invocations, except that coarse
+          * derivatives don't count as they usually only use 3 out of the 4
+          * fragments in a quad.
+          */
+         bool needs_full_quad_helper_invocations:1;
+
          /**
           * Whether any inputs are declared with the "sample" qualifier.
           */