intel/fs: Rename PLACEHOLDER_HALT to HALT_TARGET

It's a bit more explicit and will play more nicely with what we're about
to do.

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5071>

src/intel/compiler/brw_eu_defines.h

@@ -552,6 +552,13 @@ enum opcode {
 
    SHADER_OPCODE_INTERLOCK,
 
+   /** Target for a HALT
+    *
+    * All HALT instructions in a shader must target the same jump point and
+    * that point is denoted by a HALT_TARGET instruction.
+    */
+   SHADER_OPCODE_HALT_TARGET,
+
    VEC4_OPCODE_MOV_BYTES,
    VEC4_OPCODE_PACK_BYTES,
    VEC4_OPCODE_UNPACK_UNIFORM,
@@ -581,7 +588,6 @@ enum opcode {
    FS_OPCODE_DISCARD_JUMP,
    FS_OPCODE_SET_SAMPLE_ID,
    FS_OPCODE_PACK_HALF_2x16_SPLIT,
-   FS_OPCODE_PLACEHOLDER_HALT,
    FS_OPCODE_INTERPOLATE_AT_SAMPLE,
    FS_OPCODE_INTERPOLATE_AT_SHARED_OFFSET,
    FS_OPCODE_INTERPOLATE_AT_PER_SLOT_OFFSET,

src/intel/compiler/brw_fs.cpp

@@ -3035,21 +3035,21 @@ fs_visitor::opt_redundant_discard_jumps()
 
    bblock_t *last_bblock = cfg->blocks[cfg->num_blocks - 1];
 
-   fs_inst *placeholder_halt = NULL;
+   fs_inst *halt_target = NULL;
    foreach_inst_in_block_reverse(fs_inst, inst, last_bblock) {
-      if (inst->opcode == FS_OPCODE_PLACEHOLDER_HALT) {
+      if (inst->opcode == SHADER_OPCODE_HALT_TARGET) {
-         placeholder_halt = inst;
+         halt_target = inst;
          break;
       }
    }
 
-   if (!placeholder_halt)
+   if (!halt_target)
       return false;
 
-   /* Delete any HALTs immediately before the placeholder halt. */
+   /* Delete any HALTs immediately before the halt target. */
-   for (fs_inst *prev = (fs_inst *) placeholder_halt->prev;
+   for (fs_inst *prev = (fs_inst *) halt_target->prev;
         !prev->is_head_sentinel() && prev->opcode == FS_OPCODE_DISCARD_JUMP;
-        prev = (fs_inst *) placeholder_halt->prev) {
+        prev = (fs_inst *) halt_target->prev) {
       prev->remove(last_bblock);
       progress = true;
    }
@@ -7943,7 +7943,7 @@ fs_visitor::fixup_3src_null_dest()
  * Find the first instruction in the program that might start a region of
  * divergent control flow due to a HALT jump.  There is no
  * find_halt_control_flow_region_end(), the region of divergence extends until
- * the only FS_OPCODE_PLACEHOLDER_HALT in the program.
+ * the only SHADER_OPCODE_HALT_TARGET in the program.
  */
 static const fs_inst *
 find_halt_control_flow_region_start(const fs_visitor *v)
@@ -7952,7 +7952,7 @@ find_halt_control_flow_region_start(const fs_visitor *v)
        brw_wm_prog_data(v->prog_data)->uses_kill) {
       foreach_block_and_inst(block, fs_inst, inst, v->cfg) {
          if (inst->opcode == FS_OPCODE_DISCARD_JUMP ||
-             inst->opcode == FS_OPCODE_PLACEHOLDER_HALT)
+             inst->opcode == SHADER_OPCODE_HALT_TARGET)
             return inst;
       }
    }
@@ -8012,7 +8012,7 @@ fs_visitor::fixup_nomask_control_flow()
 
          case BRW_OPCODE_WHILE:
          case BRW_OPCODE_ENDIF:
-         case FS_OPCODE_PLACEHOLDER_HALT:
+         case SHADER_OPCODE_HALT_TARGET:
             depth++;
             break;
 
@@ -8528,7 +8528,7 @@ fs_visitor::run_fs(bool allow_spilling, bool do_rep_send)
 	 return false;
 
       if (wm_prog_data->uses_kill)
-         bld.emit(FS_OPCODE_PLACEHOLDER_HALT);
+         bld.emit(SHADER_OPCODE_HALT_TARGET);
 
       if (wm_key->alpha_test_func)
          emit_alpha_test();

src/intel/compiler/brw_fs.h

@@ -562,7 +562,7 @@ private:
                               struct brw_reg dst, struct brw_reg src,
                               unsigned swiz);
 
-   bool patch_discard_jumps_to_fb_writes();
+   bool patch_halt_jumps();
 
    const struct brw_compiler *compiler;
    void *log_data; /* Passed to compiler->*_log functions */

src/intel/compiler/brw_fs_cse.cpp

@@ -325,7 +325,7 @@ fs_visitor::opt_cse_local(const fs_live_variables &live, bblock_t *block, int &i
        * SHADER_OPCODE_FIND_LIVE_CHANNEL.
        */
       if (inst->opcode == FS_OPCODE_DISCARD_JUMP ||
-          inst->opcode == FS_OPCODE_PLACEHOLDER_HALT)
+          inst->opcode == SHADER_OPCODE_HALT_TARGET)
          aeb.make_empty();
 
       foreach_in_list_safe(aeb_entry, entry, &aeb) {

src/intel/compiler/brw_fs_generator.cpp

@@ -222,7 +222,7 @@ public:
 };
 
 bool
-fs_generator::patch_discard_jumps_to_fb_writes()
+fs_generator::patch_halt_jumps()
 {
    if (this->discard_halt_patches.is_empty())
       return false;
@@ -2529,11 +2529,11 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width,
           generate_pack_half_2x16_split(inst, dst, src[0], src[1]);
           break;
 
-      case FS_OPCODE_PLACEHOLDER_HALT:
+      case SHADER_OPCODE_HALT_TARGET:
          /* This is the place where the final HALT needs to be inserted if
           * we've emitted any discards.  If not, this will emit no code.
           */
-         if (!patch_discard_jumps_to_fb_writes()) {
+         if (!patch_halt_jumps()) {
             if (unlikely(debug_flag)) {
                disasm_info->use_tail = true;
             }

src/intel/compiler/brw_fs_scoreboard.cpp

@@ -76,7 +76,7 @@ namespace {
       case BRW_OPCODE_SYNC:
       case BRW_OPCODE_DO:
       case SHADER_OPCODE_UNDEF:
-      case FS_OPCODE_PLACEHOLDER_HALT:
+      case SHADER_OPCODE_HALT_TARGET:
       case FS_OPCODE_SCHEDULING_FENCE:
          return 0;
       default:

src/intel/compiler/brw_ir_performance.cpp

@@ -1098,7 +1098,7 @@ namespace {
          }
 
       case SHADER_OPCODE_UNDEF:
-      case FS_OPCODE_PLACEHOLDER_HALT:
+      case SHADER_OPCODE_HALT_TARGET:
       case FS_OPCODE_SCHEDULING_FENCE:
          return calculate_desc(info, unit_null, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0);
@@ -1552,7 +1552,7 @@ namespace {
 
             issue_instruction(st, s->devinfo, inst);
 
-            if (inst->opcode == FS_OPCODE_PLACEHOLDER_HALT && discard_count)
+            if (inst->opcode == SHADER_OPCODE_HALT_TARGET && discard_count)
                st.weight /= discard_weight;
 
             elapsed += (st.unit_ready[unit_fe] - clock0) * st.weight;

src/intel/compiler/brw_schedule_instructions.cpp

@@ -1047,7 +1047,7 @@ instruction_scheduler::add_dep(schedule_node *before, schedule_node *after)
 static bool
 is_scheduling_barrier(const backend_instruction *inst)
 {
-   return inst->opcode == FS_OPCODE_PLACEHOLDER_HALT ||
+   return inst->opcode == SHADER_OPCODE_HALT_TARGET ||
           inst->is_control_flow() ||
           inst->has_side_effects();
 }

src/intel/compiler/brw_shader.cpp

@@ -453,8 +453,8 @@ brw_instruction_name(const struct gen_device_info *devinfo, enum opcode op)
    case FS_OPCODE_PACK_HALF_2x16_SPLIT:
       return "pack_half_2x16_split";
 
-   case FS_OPCODE_PLACEHOLDER_HALT:
+   case SHADER_OPCODE_HALT_TARGET:
-      return "placeholder_halt";
+      return "halt_target";
 
    case FS_OPCODE_INTERPOLATE_AT_SAMPLE:
       return "interp_sample";