pan/mdg: Add MIDGARD_MESA_DEBUG=inorder option

Helpful to disable the scheduler when debugging, so the assembly can be
compared against the NIR directly when lost in a big dEQP test.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8973>

src/panfrost/midgard/midgard.h

@@ -34,6 +34,7 @@
 #define MIDGARD_DBG_MSGS		0x0001
 #define MIDGARD_DBG_SHADERS		0x0002
 #define MIDGARD_DBG_SHADERDB            0x0004
+#define MIDGARD_DBG_INORDER             0x0008
 
 extern int midgard_debug;
 

src/panfrost/midgard/midgard_compile.c

@@ -58,6 +58,7 @@ static const struct debug_named_value midgard_debug_options[] = {
         {"msgs",      MIDGARD_DBG_MSGS,		"Print debug messages"},
         {"shaders",   MIDGARD_DBG_SHADERS,	"Dump shaders in NIR and MIR"},
         {"shaderdb",  MIDGARD_DBG_SHADERDB,     "Prints shader-db statistics"},
+        {"inorder",   MIDGARD_DBG_INORDER,      "Disables out-of-order scheduling"},
         DEBUG_NAMED_VALUE_END
 };
 

src/panfrost/midgard/midgard_schedule.c

@@ -674,6 +674,12 @@ mir_choose_instruction(
         unsigned max_active = 0;
         unsigned max_distance = 36;
 
+#ifndef NDEBUG
+        /* Force in-order scheduling */
+        if (midgard_debug & MIDGARD_DBG_INORDER)
+                max_distance = 1;
+#endif
+
         BITSET_FOREACH_SET(i, worklist, count) {
                 max_active = MAX2(max_active, i);
         }