pan: Remove dead code for sso_abi builder and fixed_varyings

Now that the SSO ABI is never used we can remove it with all of the
plumbing code required to find the fixed varyings bits.

Signed-off-by: Lorenzo Rossi <lorenzo.rossi@collabora.com>
Acked-by: Eric R. Smith <eric.smith@collabora.com>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38681>

src/gallium/drivers/panfrost/pan_shader.c

@@ -120,14 +120,9 @@ panfrost_shader_compile(struct panfrost_screen *screen, const nir_shader *ir,
    };
 
    /* Lower this early so the backends don't have to worry about it */
-   if (s->info.stage == MESA_SHADER_FRAGMENT) {
+   if (s->info.stage == MESA_SHADER_VERTEX) {
-      inputs.fixed_varying_mask =
-         pan_get_fixed_varying_mask(s->info.inputs_read);
-   } else if (s->info.stage == MESA_SHADER_VERTEX) {
       /* No IDVS for internal XFB shaders */
       inputs.no_idvs = s->info.has_transform_feedback_varyings;
-      inputs.fixed_varying_mask =
-         pan_get_fixed_varying_mask(s->info.outputs_written);
 
       if (s->info.has_transform_feedback_varyings) {
          NIR_PASS(_, s, nir_opt_constant_folding);
@@ -153,8 +148,6 @@ panfrost_shader_compile(struct panfrost_screen *screen, const nir_shader *ir,
       if (key->fs.clip_plane_enable) {
          NIR_PASS(_, s, nir_lower_clip_fs, key->fs.clip_plane_enable,
                   false, true);
-         inputs.fixed_varying_mask =
-            pan_get_fixed_varying_mask(s->info.inputs_read);
       }
 
       if (key->fs.line_smooth) {

src/panfrost/compiler/pan_compiler.h

@@ -116,16 +116,6 @@ struct pan_compile_inputs {
    /* Mask of UBOs that may be moved to push constants */
    uint32_t pushable_ubos;
 
-   /* Used on Valhall.
-    *
-    * Bit mask of special desktop-only varyings (e.g VARYING_SLOT_TEX0)
-    * written by the previous stage (fragment shader) or written by this
-    * stage (vertex shader). Bits are slots from gl_varying_slot.
-    *
-    * For modern APIs (GLES or VK), this should be 0.
-    */
-   uint32_t fixed_varying_mask;
-
    /* Varying layout in memory, if known */
    const struct pan_varying_layout *varying_layout;
 
@@ -268,13 +258,6 @@ pan_varying_layout_slot_at(const struct pan_varying_layout *layout,
    return slot;
 }
 
-static inline uint32_t
-pan_get_fixed_varying_mask(unsigned varyings_used)
-{
-   return (varyings_used & BITFIELD_MASK(VARYING_SLOT_VAR0)) &
-      ~VARYING_BIT_POS & ~PAN_ATTRIB_VARYING_BITS;
-}
-
 static inline void
 pan_varying_layout_require_format(const struct pan_varying_layout *layout)
 {
@@ -294,16 +277,6 @@ pan_varying_layout_require_layout(const struct pan_varying_layout *layout)
 enum pipe_format
 pan_varying_format(nir_alu_type type, unsigned ncomps);
 
-/** Builds a varying layout according to the SSO ABI we developed for OpenGL.
- *
- * This can be called on either shader stage and the two varying layouts are
- * guaranteed to match if the same fixed_varyings are passed into both.
- */
-void
-pan_build_varying_layout_sso_abi(struct pan_varying_layout *layout,
-                                 nir_shader *nir, unsigned gpu_id,
-                                 uint32_t fixed_varyings);
-
 void
 pan_build_varying_layout_compact(struct pan_varying_layout *layout,
                                  nir_shader *nir, unsigned gpu_id);

src/panfrost/compiler/pan_nir_collect_varyings.c

@@ -379,43 +379,6 @@ pan_varying_collect_formats(struct pan_varying_layout *layout, nir_shader *nir,
    layout->known |= PAN_VARYING_FORMAT_KNOWN;
 }
 
-void
-pan_build_varying_layout_sso_abi(struct pan_varying_layout *layout,
-                                 nir_shader *nir, unsigned gpu_id,
-                                 uint32_t fixed_varyings)
-{
-   pan_varying_layout_require_format(layout);
-
-   const unsigned gpu_arch = pan_arch(gpu_id);
-   unsigned generic_size_B = 0;
-   for (unsigned i = 0; i < layout->count; i++) {
-      struct pan_varying_slot *slot = &layout->slots[i];
-      if (pan_varying_slot_is_empty(slot))
-         continue;
-
-      if (slot->section != PAN_VARYING_SECTION_GENERIC) {
-         ASSERTED const struct pan_varying_slot hw_slot =
-            hw_varying_slot(gpu_arch, nir->info.stage, slot->location);
-
-         assert(memcmp(slot, &hw_slot, sizeof(*slot)) == 0);
-      } else {
-         unsigned offset =
-            bi_varying_base_bytes(slot->location, fixed_varyings);
-         assert(offset < (1 << 11));
-
-         const unsigned bit_size = nir_alu_type_get_type_size(slot->alu_type);
-         const unsigned size = slot->ncomps * (bit_size / 8);
-         generic_size_B = MAX2(generic_size_B, offset + size);
-
-         assert(slot->offset == -1);
-         assert(offset < 4096);
-         slot->offset = offset;
-      }
-   }
-   layout->generic_size_B = generic_size_B;
-   layout->known |= PAN_VARYING_LAYOUT_KNOWN;
-}
-
 void
 pan_build_varying_layout_compact(struct pan_varying_layout *layout,
                                  nir_shader *nir, unsigned gpu_id)