From ac339e6ace2dac59bec0db14aad0aee72d64c3d4 Mon Sep 17 00:00:00 2001
From: Lorenzo Rossi <lorenzo.rossi@collabora.com>
Date: Mon, 4 May 2026 15:24:22 +0200
Subject: [PATCH] pan/bi: Add a printing helper for pan_varying_layout

This is just something I had to type again and again to figure out
layout bugs, maybe it's better to just write it once and leave it
disabled by default. Right now it's not printing nir_alu_type since the
printing functions are private in nir_print.c and I don't want to expose
that.

Signed-off-by: Lorenzo Rossi <lorenzo.rossi@collabora.com>
Reviewed-by: Lars-Ivar Hesselberg Simonsen <lars-ivar.simonsen@arm.com>
---
 .../compiler/pan_nir_collect_varyings.c       | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/panfrost/compiler/pan_nir_collect_varyings.c b/src/panfrost/compiler/pan_nir_collect_varyings.c
index a9556b073c5..c7a43af4b7b 100644
--- a/src/panfrost/compiler/pan_nir_collect_varyings.c
+++ b/src/panfrost/compiler/pan_nir_collect_varyings.c
@@ -9,6 +9,8 @@
 #include "pan_nir.h"
 #include "panfrost/model/pan_model.h"
 
+#define DEBUG_PRINT false
+
 enum pipe_format
 pan_varying_format(nir_alu_type t, unsigned ncomps)
 {
@@ -47,6 +49,49 @@ pan_varying_format(nir_alu_type t, unsigned ncomps)
    UNREACHABLE("Invalid type");
 }
 
+static void
+pan_print_varying_layout(FILE *f, nir_shader *s,
+                         const struct pan_varying_layout *layout)
+{
+   const char *section_name[] = {
+      "POSITION",
+      "ATTRIBS",
+      "SPECIAL",
+      "GENERIC"
+   };
+
+   fprintf(f, "Layout for %s (%s):\n", s->info.name,
+           mesa_shader_stage_name(s->info.stage));
+   fprintf(f, "Known:");
+   if (layout->known == 0) {
+      fprintf(f, " empty");
+   } else {
+      if (layout->known & PAN_VARYING_FORMAT_KNOWN)
+         fprintf(f, " format");
+      if (layout->known & PAN_VARYING_LAYOUT_KNOWN)
+         fprintf(f, " layout");
+   }
+   fprintf(f, "\n");
+
+   fprintf(f, "Varying count: %d\n", layout->count);
+   if (layout->known & PAN_VARYING_LAYOUT_KNOWN)
+      fprintf(f, "Generic size (bytes): %x\n", layout->generic_size_B);
+   for (unsigned i = 0; i < layout->count; i++) {
+      const struct pan_varying_slot *slot =
+         pan_varying_layout_slot_at(layout, i);
+      if (slot == NULL)
+         continue;
+      const char *loc_name =
+         gl_varying_slot_name_for_stage(slot->location, s->info.stage);
+      fprintf(f, "%02d: %s alu=%x comps=%d", i, loc_name, slot->alu_type,
+              slot->ncomps);
+      if (layout->known & PAN_VARYING_LAYOUT_KNOWN)
+         fprintf(f, " off=%x section=%s", slot->offset,
+                 section_name[slot->section]);
+      fprintf(f, "\n");
+   }
+}
+
 struct slot_info {
    nir_alu_type type;
    bool any_highp;
@@ -359,6 +404,9 @@ pan_varying_collect_formats(struct pan_varying_layout *layout, nir_shader *nir,
    layout->count = count;
    layout->generic_size_B = 0;
    layout->known |= PAN_VARYING_FORMAT_KNOWN;
+
+   if (DEBUG_PRINT)
+      pan_print_varying_layout(stderr, nir, layout);
 }
 
 void
@@ -394,4 +442,7 @@ pan_build_varying_layout_compact(struct pan_varying_layout *layout,
    }
    layout->generic_size_B = generic_size_B;
    layout->known |= PAN_VARYING_LAYOUT_KNOWN;
+
+   if (DEBUG_PRINT)
+      pan_print_varying_layout(stderr, nir, layout);
 }