brw: Add brw_reg::is_grf

v2: Add a function comment. Suggested by Caio.

Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38315>

src/intel/compiler/brw/brw_opt_copy_propagation.cpp

@@ -704,8 +704,7 @@ try_copy_propagate(brw_shader &s, brw_inst *inst,
 
    const struct intel_device_info *devinfo = s.devinfo;
 
-   assert(entry->src.file == VGRF || entry->src.file == UNIFORM ||
-          entry->src.file == ATTR || entry->src.file == FIXED_GRF);
+   assert(entry->src.is_grf());
 
    /* Avoid propagating a LOAD_PAYLOAD instruction into another if there is a
     * good chance that we'll be able to eliminate the latter through register

src/intel/compiler/brw/brw_reg.h

@@ -233,6 +233,17 @@ typedef struct brw_reg {
    bool is_ip() const { return brw_reg_is_arf(*this, BRW_ARF_IP); }
    bool is_address() const;
 
+   /**
+    * These are all the things that will eventually become FIXED_GRF. The
+    * things that will live in regular registers can, for the most part, be
+    * treated the same by optimization passes.
+    */
+   bool is_grf() const
+   {
+      return file == FIXED_GRF || file == VGRF || file == ATTR ||
+             file == UNIFORM;
+   }
+
    unsigned address_slot(unsigned byte_offset) const;
 
    /**