zink: enable tgsi texcoord pipe cap

this requires some modifications to the ntv slot remapping, as we definitely
don't want to reserve another 25% of the available slots for the (deprecated)
texcoord varyings

now we remap VARYING_SLOT_TEX[n] to the last available slots, which lets us avoid
needing to do permanent reservation, and we check to make sure that we haven't
seen the corresponding texcoord varying any time we emit a non-texcoord varying in
that slot

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5551>

src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.c

@@ -36,15 +36,15 @@ static unsigned slot_pack_map[] = {
    [VARYING_SLOT_COL0] = 0, /* input/output */
    [VARYING_SLOT_COL1] = 1, /* input/output */
    [VARYING_SLOT_FOGC] = 2, /* input/output */
-   /* TEX0-7 are translated to VAR0-7 by nir, so we don't need to reserve */
-   [VARYING_SLOT_TEX0] = UINT_MAX, /* input/output */
-   [VARYING_SLOT_TEX1] = UINT_MAX,
-   [VARYING_SLOT_TEX2] = UINT_MAX,
-   [VARYING_SLOT_TEX3] = UINT_MAX,
-   [VARYING_SLOT_TEX4] = UINT_MAX,
-   [VARYING_SLOT_TEX5] = UINT_MAX,
-   [VARYING_SLOT_TEX6] = UINT_MAX,
-   [VARYING_SLOT_TEX7] = UINT_MAX,
+   /* TEX0-7 are deprecated, so we put them at the end of the range and hope nobody uses them all */
+   [VARYING_SLOT_TEX0] = VARYING_SLOT_VAR0 - 1, /* input/output */
+   [VARYING_SLOT_TEX1] = VARYING_SLOT_VAR0 - 2,
+   [VARYING_SLOT_TEX2] = VARYING_SLOT_VAR0 - 3,
+   [VARYING_SLOT_TEX3] = VARYING_SLOT_VAR0 - 4,
+   [VARYING_SLOT_TEX4] = VARYING_SLOT_VAR0 - 5,
+   [VARYING_SLOT_TEX5] = VARYING_SLOT_VAR0 - 6,
+   [VARYING_SLOT_TEX6] = VARYING_SLOT_VAR0 - 7,
+   [VARYING_SLOT_TEX7] = VARYING_SLOT_VAR0 - 8,
 
    /* PointSize is builtin */
    [VARYING_SLOT_PSIZ] = UINT_MAX,
@@ -122,6 +122,9 @@ struct ntv_context {
    SpvId loop_break, loop_cont;
 
    SpvId front_face_var, instance_id_var, vertex_id_var;
+#ifndef NDEBUG
+   bool seen_texcoord[8]; //whether we've seen a VARYING_SLOT_TEX[n] this pass
+#endif
 };
 
 static SpvId
@@ -284,6 +287,28 @@ get_glsl_type(struct ntv_context *ctx, const struct glsl_type *type)
    unreachable("we shouldn't get here, I think...");
 }
 
+static inline unsigned
+handle_slot(struct ntv_context *ctx, unsigned slot)
+{
+   unsigned orig = slot;
+   if (slot < VARYING_SLOT_VAR0) {
+#ifndef NDEBUG
+      if (slot >= VARYING_SLOT_TEX0 && slot <= VARYING_SLOT_TEX7)
+         ctx->seen_texcoord[slot - VARYING_SLOT_TEX0] = true;
+#endif
+      slot = slot_pack_map[slot];
+      if (slot == UINT_MAX)
+         debug_printf("unhandled varying slot: %s\n", gl_varying_slot_name(orig));
+   } else {
+      slot -= VARYING_SLOT_VAR0 - NTV_MIN_RESERVED_SLOTS;
+      assert(slot <= VARYING_SLOT_VAR0 - 8 ||
+             !ctx->seen_texcoord[VARYING_SLOT_VAR0 - slot - 1]);
+
+   }
+   assert(slot < VARYING_SLOT_VAR0);
+   return slot;
+}
+
 #define HANDLE_EMIT_BUILTIN(SLOT, BUILTIN) \
       case VARYING_SLOT_##SLOT: \
          spirv_builder_emit_builtin(&ctx->builder, var_id, SpvBuiltIn##BUILTIN); \
@@ -316,13 +341,7 @@ emit_input(struct ntv_context *ctx, struct nir_variable *var)
       HANDLE_EMIT_BUILTIN(FACE, FrontFacing);
 
       default:
-         if (slot < VARYING_SLOT_VAR0) {
-            slot = slot_pack_map[slot];
-            if (slot == UINT_MAX)
-               debug_printf("unhandled varying slot: %s\n", gl_varying_slot_name(var->data.location));
-         } else
-            slot -= VARYING_SLOT_VAR0 - NTV_MIN_RESERVED_SLOTS;
-         assert(slot < VARYING_SLOT_VAR0);
+         slot = handle_slot(ctx, slot);
          spirv_builder_emit_location(&ctx->builder, var_id, slot);
       }
    } else {
@@ -378,17 +397,8 @@ emit_output(struct ntv_context *ctx, struct nir_variable *var)
          break;
 
       default:
-         if (slot < VARYING_SLOT_VAR0) {
-            slot = slot_pack_map[slot];
-            if (slot == UINT_MAX)
-               debug_printf("unhandled varying slot: %s\n", gl_varying_slot_name(var->data.location));
-         } else
-            slot -= VARYING_SLOT_VAR0 - NTV_MIN_RESERVED_SLOTS;
-         assert(slot < VARYING_SLOT_VAR0);
+         slot = handle_slot(ctx, slot);
          spirv_builder_emit_location(&ctx->builder, var_id, slot);
-         /* non-builtins get location incremented by VARYING_SLOT_VAR0 in vtn, so
-          * use driver_location for non-builtins with defined slots to avoid overlap
-          */
       }
       ctx->outputs[var->data.location] = var_id;
       ctx->so_output_gl_types[var->data.location] = var->type;
@@ -895,6 +905,8 @@ emit_so_info(struct ntv_context *ctx, unsigned max_output_location,
       if (max_output_location >= VARYING_SLOT_VAR0)
          location = max_output_location - VARYING_SLOT_VAR0 + 1 + i;
       assert(location < VARYING_SLOT_VAR0);
+      assert(location <= VARYING_SLOT_VAR0 - 8 ||
+             !ctx->seen_texcoord[VARYING_SLOT_VAR0 - location - 1]);
       spirv_builder_emit_location(&ctx->builder, var_id, location);
 
       /* note: gl_ClipDistance[4] can the 0-indexed member of VARYING_SLOT_CLIP_DIST1 here,

src/gallium/drivers/zink/zink_screen.c

@@ -95,6 +95,7 @@ zink_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 
    switch (param) {
    case PIPE_CAP_NPOT_TEXTURES:
+   case PIPE_CAP_TGSI_TEXCOORD:
       return 1;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS: