brw: fix Wa_22013689345 emission

2 problems :
  - not detecting null destination correctly
  - applied too late using SHADER_OPCODE_MEMORY_FENCE, when lowering
    already happened

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: mesa-stable
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34319>

src/intel/compiler/brw_compile_bs.cpp

@@ -53,7 +53,6 @@ run_bs(brw_shader &s, bool allow_spilling)
    s.assign_curb_setup();
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, allow_spilling);

src/intel/compiler/brw_compile_cs.cpp

@@ -79,7 +79,6 @@ run_cs(brw_shader &s, bool allow_spilling)
    s.assign_curb_setup();
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, allow_spilling);

src/intel/compiler/brw_compile_fs.cpp

@@ -1463,7 +1463,6 @@ run_fs(brw_shader &s, bool allow_spilling, bool do_rep_send)
       brw_assign_urb_setup(s);
 
       brw_lower_3src_null_dest(s);
-      brw_workaround_memory_fence_before_eot(s);
       brw_workaround_emit_dummy_mov_instruction(s);
 
       brw_allocate_registers(s, allow_spilling);

src/intel/compiler/brw_compile_gs.cpp

@@ -123,7 +123,6 @@ run_gs(brw_shader &s)
    brw_assign_gs_urb_setup(s);
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, true /* allow_spilling */);

src/intel/compiler/brw_compile_mesh.cpp

@@ -337,7 +337,6 @@ run_task_mesh(brw_shader &s, bool allow_spilling)
    s.assign_curb_setup();
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, allow_spilling);

src/intel/compiler/brw_compile_tcs.cpp

@@ -171,7 +171,6 @@ run_tcs(brw_shader &s)
    brw_assign_tcs_urb_setup(s);
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, true /* allow_spilling */);

src/intel/compiler/brw_compile_tes.cpp

@@ -49,7 +49,6 @@ run_tes(brw_shader &s)
    brw_assign_tes_urb_setup(s);
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, true /* allow_spilling */);

src/intel/compiler/brw_compile_vs.cpp

@@ -217,7 +217,6 @@ run_vs(brw_shader &s)
    brw_assign_vs_urb_setup(s);
 
    brw_lower_3src_null_dest(s);
-   brw_workaround_memory_fence_before_eot(s);
    brw_workaround_emit_dummy_mov_instruction(s);
 
    brw_allocate_registers(s, true /* allow_spilling */);

src/intel/compiler/brw_opt.cpp

@@ -196,6 +196,9 @@ brw_optimize(brw_shader &s)
 
    OPT(brw_lower_uniform_pull_constant_loads);
 
+   /* Do this before brw_lower_send_descriptors. */
+   OPT(brw_workaround_memory_fence_before_eot);
+
    if (OPT(brw_lower_send_descriptors)) {
       /* No need for standard copy_propagation since
        * brw_opt_address_reg_load will only optimize defs.

src/intel/compiler/brw_workaround.cpp

@@ -65,7 +65,7 @@ needs_dummy_fence(const intel_device_info *devinfo, brw_inst *inst)
    }
 
    /* Any UGM Atomic message WITHOUT return value */
-   if (lsc_opcode_is_atomic(opcode) && inst->dst.file == BAD_FILE)
+   if (lsc_opcode_is_atomic(opcode) && inst->dst.is_null())
       return true;
 
    return false;
@@ -88,6 +88,11 @@ brw_workaround_memory_fence_before_eot(brw_shader &s)
    if (!intel_needs_workaround(s.devinfo, 22013689345))
       return false;
 
+   /* Needs to happen after brw_lower_logical_sends & before
+    * brw_lower_send_descriptors.
+    */
+   assert(s.phase == BRW_SHADER_PHASE_AFTER_MIDDLE_LOWERING);
+
    foreach_block_and_inst_safe (block, brw_inst, inst, s.cfg) {
       if (!inst->eot) {
          if (needs_dummy_fence(s.devinfo, inst))
@@ -101,9 +106,15 @@ brw_workaround_memory_fence_before_eot(brw_shader &s)
       const brw_builder ubld = brw_builder(inst).uniform();
 
       brw_reg dst = ubld.vgrf(BRW_TYPE_UD);
-      brw_inst *dummy_fence = ubld.emit(SHADER_OPCODE_MEMORY_FENCE,
-                                       dst, brw_vec8_grf(0, 0),
-                                       /* commit enable */ brw_imm_ud(1));
+      brw_inst *dummy_fence = ubld.emit(SHADER_OPCODE_SEND, dst);
+
+      dummy_fence->resize_sources(4);
+      dummy_fence->src[0] = brw_imm_ud(0);
+      dummy_fence->src[1] = brw_imm_ud(0);
+      dummy_fence->src[2] = brw_vec8_grf(0, 0);
+      dummy_fence->src[3] = brw_reg();
+      dummy_fence->mlen = reg_unit(s.devinfo);
+      dummy_fence->ex_mlen = 0;
       dummy_fence->sfid = BRW_SFID_UGM;
       dummy_fence->desc = lsc_fence_msg_desc(s.devinfo, LSC_FENCE_TILE,
                                              LSC_FLUSH_TYPE_NONE_6, false);