amd: support load_front_face_fsign

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32791>

src/amd/compiler/aco_instruction_selection.cpp

@@ -8145,6 +8145,10 @@ visit_intrinsic(isel_context* ctx, nir_intrinsic_instr* instr)
                Operand::zero(), get_arg(ctx, ctx->args->front_face));
       break;
    }
+   case nir_intrinsic_load_front_face_fsign: {
+      bld.copy(Definition(get_ssa_temp(ctx, &instr->def)), get_arg(ctx, ctx->args->front_face));
+      break;
+   }
    case nir_intrinsic_load_view_index: {
       Temp dst = get_ssa_temp(ctx, &instr->def);
       bld.copy(Definition(dst), Operand(get_arg(ctx, ctx->args->view_index)));

src/amd/compiler/aco_instruction_selection_setup.cpp

@@ -559,6 +559,7 @@ init_context(isel_context* ctx, nir_shader* shader)
                case nir_intrinsic_load_barycentric_centroid:
                case nir_intrinsic_load_barycentric_at_offset:
                case nir_intrinsic_load_interpolated_input:
+               case nir_intrinsic_load_front_face_fsign:
                case nir_intrinsic_load_frag_coord:
                case nir_intrinsic_load_pixel_coord:
                case nir_intrinsic_load_frag_shading_rate:

src/amd/llvm/ac_nir_to_llvm.c

@@ -3045,6 +3045,9 @@ static bool visit_intrinsic(struct ac_nir_context *ctx, nir_intrinsic_instr *ins
       result = emit_float_cmp(&ctx->ac, LLVMRealOLT, ctx->ac.f32_0,
                               ac_get_arg(&ctx->ac, ctx->args->front_face));
       break;
+   case nir_intrinsic_load_front_face_fsign:
+      result = ac_get_arg(&ctx->ac, ctx->args->front_face);
+      break;
    case nir_intrinsic_load_helper_invocation:
    case nir_intrinsic_is_helper_invocation:
       result = ac_build_load_helper_invocation(&ctx->ac);

src/amd/vulkan/radv_shader_info.c

@@ -960,7 +960,8 @@ gather_shader_info_fs(const struct radv_device *device, const nir_shader *nir,
    info->ps.reads_sample_mask_in = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_SAMPLE_MASK_IN);
    info->ps.reads_sample_id = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_SAMPLE_ID);
    info->ps.reads_frag_shading_rate = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRAG_SHADING_RATE);
-   info->ps.reads_front_face = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE);
+   info->ps.reads_front_face = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE) |
+                               BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE_FSIGN);
    info->ps.reads_barycentric_model = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_BARYCENTRIC_PULL_MODEL);
    info->ps.reads_fully_covered = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FULLY_COVERED);
 

src/gallium/drivers/radeonsi/si_nir_lower_abi.c

@@ -603,9 +603,13 @@ static bool lower_intrinsic(nir_builder *b, nir_instr *instr, struct lower_abi_s
       replacement = ac_nir_load_arg(b, &args->ac, args->alpha_reference);
       break;
    case nir_intrinsic_load_front_face:
+   case nir_intrinsic_load_front_face_fsign:
       if (!key->ps.opt.force_front_face_input)
          return false;
-      replacement = nir_imm_bool(b, key->ps.opt.force_front_face_input == 1);
+      if (intrin->intrinsic == nir_intrinsic_load_front_face)
+         replacement = nir_imm_bool(b, key->ps.opt.force_front_face_input == 1);
+      else
+         replacement = nir_imm_float(b, key->ps.opt.force_front_face_input == 1 ? 1.0 : -1.0);
       break;
    case nir_intrinsic_load_barycentric_optimize_amd: {
       nir_def *prim_mask = ac_nir_load_arg(b, &args->ac, args->ac.prim_mask);

src/gallium/drivers/radeonsi/si_shader_info.c

@@ -595,7 +595,8 @@ void si_nir_scan_shader(struct si_screen *sscreen, struct nir_shader *nir,
       (BITFIELD64_BIT(VARYING_SLOT_TESS_LEVEL_INNER) |
        BITFIELD64_BIT(VARYING_SLOT_TESS_LEVEL_OUTER));
 
-   info->uses_frontface = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE);
+   info->uses_frontface = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE) |
+                          BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_FRONT_FACE_FSIGN);
    info->uses_instanceid = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_INSTANCE_ID);
    info->uses_base_vertex = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_BASE_VERTEX);
    info->uses_base_instance = BITSET_TEST(nir->info.system_values_read, SYSTEM_VALUE_BASE_INSTANCE);