IABSD.fr/xenocara/lib/mesa/src/intel/compiler/intel_nir_lower_conversions.c

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• Author : jsg
  Date : 2025-06-05 11:23:11
  Hash : 67d6f117
  Message : Import Mesa 25.0.7

• lib/mesa/src/intel/compiler/intel_nir_lower_conversions.c

• /*
   * Copyright © 2018 Intel Corporation
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  #include "intel_nir.h"
  #include "compiler/nir/nir_builder.h"
  
  static void
  split_conversion(nir_builder *b, nir_alu_instr *alu, nir_alu_type src_type,
                   nir_alu_type tmp_type, nir_alu_type dst_type)
  {
     b->cursor = nir_before_instr(&alu->instr);
     nir_def *src = nir_ssa_for_alu_src(b, alu, 0);
     nir_def *tmp = nir_type_convert(b, src, src_type, tmp_type, nir_rounding_mode_undef);
     nir_def *res = nir_type_convert(b, tmp, tmp_type, dst_type, nir_rounding_mode_undef);
     nir_def_replace(&alu->def, res);
  }
  
  static bool
  lower_alu_instr(nir_builder *b, nir_alu_instr *alu)
  {
     unsigned src_bit_size = nir_src_bit_size(alu->src[0].src);
     nir_alu_type src_type = nir_op_infos[alu->op].input_types[0];
     nir_alu_type src_full_type = (nir_alu_type) (src_type | src_bit_size);
  
     unsigned dst_bit_size = alu->def.bit_size;
     nir_alu_type dst_full_type = nir_op_infos[alu->op].output_type;
     nir_alu_type dst_type = nir_alu_type_get_base_type(dst_full_type);
  
     /* BDW PRM, vol02, Command Reference Instructions, mov - MOVE:
      *
      *   "There is no direct conversion from HF to DF or DF to HF.
      *    Use two instructions and F (Float) as an intermediate type.
      *
      *    There is no direct conversion from HF to Q/UQ or Q/UQ to HF.
      *    Use two instructions and F (Float) or a word integer type
      *    or a DWord integer type as an intermediate type."
      *
      * It is important that the intermediate conversion happens through a
      * 32-bit float type so we don't lose range when we convert from
      * a 64-bit integer.
      */
     if ((src_full_type == nir_type_float16 && dst_bit_size == 64) ||
         (src_bit_size == 64 && dst_full_type == nir_type_float16)) {
        split_conversion(b, alu, src_type, nir_type_float | 32,
                         dst_type | dst_bit_size);
        return true;
     }
  
     /* SKL PRM, vol 02a, Command Reference: Instructions, Move:
      *
      *   "There is no direct conversion from B/UB to DF or DF to B/UB. Use
      *    two instructions and a word or DWord intermediate type."
      *
      *   "There is no direct conversion from B/UB to Q/UQ or Q/UQ to B/UB.
      *    Use two instructions and a word or DWord intermediate integer
      *    type."
      *
      * It is important that we use a 32-bit integer matching the sign of the
      * destination as the intermediate type so we avoid any chance of rtne
      * rounding happening before the conversion to integer (which is expected
      * to round towards zero) in double to byte conversions.
      */
     if ((src_bit_size == 8 && dst_bit_size == 64) ||
         (src_bit_size == 64 && dst_bit_size == 8)) {
        split_conversion(b, alu, src_type, dst_type | 32, dst_type | dst_bit_size);
        return true;
     }
  
     return false;
  }
  
  static bool
  lower_instr(nir_builder *b, nir_instr *instr, UNUSED void *cb_data)
  {
     if (instr->type != nir_instr_type_alu)
        return false;
  
     nir_alu_instr *alu = nir_instr_as_alu(instr);
  
     if (!nir_op_infos[alu->op].is_conversion)
        return false;
  
     return lower_alu_instr(b, alu);
  }
  
  bool
  intel_nir_lower_conversions(nir_shader *shader)
  {
     return nir_shader_instructions_pass(shader, lower_instr,
                                         nir_metadata_control_flow,
                                         NULL);
  }