src/intel/compiler/brw_spirv.c

/*
 * Copyright © 2025 Intel Corporation
 * SPDX-License-Identifier: MIT
 */

#include "brw_nir.h"
#include "intel_nir.h"

#include "intel_nir.h"
#include "compiler/nir/nir_builder.h"
#include "compiler/spirv/nir_spirv.h"
#include "compiler/spirv/spirv_info.h"
#include "dev/intel_debug.h"
#include "util/u_dynarray.h"

static void
optimize(nir_shader *nir)
{
   bool progress;
   do {
      progress = false;

      NIR_PASS(progress, nir, nir_split_var_copies);
      NIR_PASS(progress, nir, nir_split_struct_vars, nir_var_function_temp);
      NIR_PASS(progress, nir, nir_lower_var_copies);
      NIR_PASS(progress, nir, nir_lower_vars_to_ssa);

      NIR_PASS(progress, nir, nir_copy_prop);
      NIR_PASS(progress, nir, nir_opt_remove_phis);
      NIR_PASS(progress, nir, nir_lower_all_phis_to_scalar);
      NIR_PASS(progress, nir, nir_opt_dce);
      NIR_PASS(progress, nir, nir_opt_dead_cf);
      NIR_PASS(progress, nir, nir_opt_cse);

      nir_opt_peephole_select_options peephole_select_options = {
         .limit = 64,
         .expensive_alu_ok = true,
      };
      NIR_PASS(progress, nir, nir_opt_peephole_select, &peephole_select_options);
      NIR_PASS(progress, nir, nir_opt_phi_precision);
      NIR_PASS(progress, nir, nir_opt_algebraic);
      NIR_PASS(progress, nir, nir_opt_constant_folding);

      NIR_PASS(progress, nir, nir_opt_deref);
      NIR_PASS(progress, nir, nir_opt_copy_prop_vars);
      NIR_PASS(progress, nir, nir_opt_undef);
      NIR_PASS(progress, nir, nir_lower_undef_to_zero);

      NIR_PASS(progress, nir, nir_opt_shrink_vectors, true);
      NIR_PASS(progress, nir, nir_opt_loop_unroll);

   } while (progress);
}

nir_shader *
brw_nir_from_spirv(void *mem_ctx, const uint32_t *spirv, size_t spirv_size)
{
   static const struct spirv_capabilities spirv_caps = {
      .Addresses = true,
      .Float16 = true,
      .Float64 = true,
      .Groups = true,
      .StorageImageWriteWithoutFormat = true,
      .Int8 = true,
      .Int16 = true,
      .Int64 = true,
      .Int64Atomics = true,
      .Kernel = true,
      .Linkage = true, /* We receive linked kernel from clc */
      .DenormFlushToZero = true,
      .DenormPreserve = true,
      .SignedZeroInfNanPreserve = true,
      .RoundingModeRTE = true,
      .RoundingModeRTZ = true,
      .GenericPointer = true,
      .GroupNonUniform = true,
      .GroupNonUniformArithmetic = true,
      .GroupNonUniformClustered = true,
      .GroupNonUniformBallot = true,
      .GroupNonUniformQuad = true,
      .GroupNonUniformShuffle = true,
      .GroupNonUniformVote = true,
      .SubgroupDispatch = true,
   };
   struct spirv_to_nir_options spirv_options = {
      .environment = NIR_SPIRV_OPENCL,
      .capabilities = &spirv_caps,
      .printf = true,
      .shared_addr_format = nir_address_format_62bit_generic,
      .global_addr_format = nir_address_format_62bit_generic,
      .temp_addr_format = nir_address_format_62bit_generic,
      .constant_addr_format = nir_address_format_64bit_global,
      .create_library = true,
   };

   assert(spirv_size % 4 == 0);

   const nir_shader_compiler_options *nir_options = &brw_scalar_nir_options;

   nir_shader *nir =
      spirv_to_nir(spirv, spirv_size / 4, NULL, 0, MESA_SHADER_KERNEL,
                   "library", &spirv_options, nir_options);
   nir_validate_shader(nir, "after spirv_to_nir");
   nir_validate_ssa_dominance(nir, "after spirv_to_nir");
   ralloc_steal(mem_ctx, nir);
   nir->info.name = ralloc_strdup(nir, "library");

   nir_fixup_is_exported(nir);

   NIR_PASS(_, nir, nir_lower_system_values);
   NIR_PASS(_, nir, nir_lower_calls_to_builtins);

   NIR_PASS(_, nir, nir_lower_variable_initializers, nir_var_function_temp);
   NIR_PASS(_, nir, nir_lower_returns);
   NIR_PASS(_, nir, nir_inline_functions);
   //nir_remove_non_exported(nir);
   NIR_PASS(_, nir, nir_copy_prop);
   NIR_PASS(_, nir, nir_opt_deref);

   /* We can't deal with constant data, get rid of it */
   nir_lower_constant_to_temp(nir);

   /* We can go ahead and lower the rest of the constant initializers.  We do
    * this here so that nir_remove_dead_variables and split_per_member_structs
    * below see the corresponding stores.
    */
   NIR_PASS(_, nir, nir_lower_variable_initializers, ~0);

   /* LLVM loves take advantage of the fact that vec3s in OpenCL are 16B
    * aligned and so it can just read/write them as vec4s.  This results in a
    * LOT of vec4->vec3 casts on loads and stores.  One solution to this
    * problem is to get rid of all vec3 variables.
    */
   NIR_PASS(_, nir, nir_lower_vec3_to_vec4,
            nir_var_shader_temp | nir_var_function_temp | nir_var_mem_shared |
               nir_var_mem_global | nir_var_mem_constant);

   /* We assign explicit types early so that the optimizer can take advantage
    * of that information and hopefully get rid of some of our memcpys.
    */
   NIR_PASS(_, nir, nir_lower_vars_to_explicit_types,
            nir_var_uniform | nir_var_shader_temp | nir_var_function_temp |
               nir_var_mem_shared | nir_var_mem_global,
            glsl_get_cl_type_size_align);

   optimize(nir);

   NIR_PASS(_, nir, nir_remove_dead_variables, nir_var_all, NULL);

   /* Lower again, this time after dead-variables to get more compact variable
    * layouts.
    */
   NIR_PASS(_, nir, nir_lower_vars_to_explicit_types,
            nir_var_shader_temp | nir_var_function_temp | nir_var_mem_shared |
               nir_var_mem_global | nir_var_mem_constant,
            glsl_get_cl_type_size_align);
   assert(nir->constant_data_size == 0);

   NIR_PASS(_, nir, nir_lower_memcpy);

   NIR_PASS(_, nir, nir_lower_explicit_io, nir_var_mem_constant,
            nir_address_format_64bit_global);

   NIR_PASS(_, nir, nir_lower_explicit_io, nir_var_uniform,
            nir_address_format_64bit_global);

   /* Note: we cannot lower explicit I/O here, because we need derefs in tact
    * for function calls into the library to work.
    */

   NIR_PASS(_, nir, nir_lower_convert_alu_types, NULL);
   NIR_PASS(_, nir, nir_opt_if, 0);
   NIR_PASS(_, nir, nir_opt_idiv_const, 16);

   optimize(nir);

   return nir;
}