/*
 * Copyright 2022 Google LLC
 * SPDX-License-Identifier: MIT
 */

#include "ir3.h"

/*
 * Mark (ul) on the last user of a0 before a0 is loaded again.  emit_block
 * makes sure a0 is loaded first if there is any user in the block.  This
 * allows us to process each block independently.
 *
 * Note that this must be called before passes that break the assumption, such
 * as ir3_lower_subgroups.
 */

static bool
is_reg_relative(const struct ir3_instruction *instr)
{
   foreach_dst (reg, instr) {
      if (reg->flags & IR3_REG_RELATIV)
         return true;
   }

   foreach_src (reg, instr) {
      if (reg->flags & IR3_REG_RELATIV)
         return true;
   }

   return false;
}

static bool
is_dst_a0(const struct ir3_instruction *instr)
{
   foreach_dst (reg, instr) {
      if (reg->num == regid(REG_A0, 0))
         return true;
   }

   return false;
}

bool
ir3_legalize_relative(struct ir3 *ir)
{
   foreach_block (block, &ir->block_list) {
      struct ir3_instruction *last_user = NULL;

      foreach_instr (instr, &block->instr_list) {
         if (is_reg_relative(instr))
            last_user = instr;

         /* Is it valid to have address reg loaded from a relative src (ie.
          * mova a0, c<a0.x+4>)?  This marks the load (ul), which may or may
          * not be valid.
          */
         if (last_user && is_dst_a0(instr)) {
            last_user->flags |= IR3_INSTR_UL;
            last_user = NULL;
         }
      }

      if (last_user)
         last_user->flags |= IR3_INSTR_UL;
   }

   return true;
}