mesa/src/mesa/drivers/dri/i965/brw_fs_nir.cpp

/*
 * Copyright © 2010 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 "glsl/ir.h"
#include "glsl/ir_optimization.h"
#include "glsl/nir/glsl_to_nir.h"
#include "program/prog_to_nir.h"
#include "brw_fs.h"
#include "brw_nir.h"

using namespace brw;

void
fs_visitor::emit_nir_code()
{
   nir_shader *nir = prog->nir;

   /* emit the arrays used for inputs and outputs - load/store intrinsics will
    * be converted to reads/writes of these arrays
    */

   if (nir->num_inputs > 0) {
      nir_inputs = bld.vgrf(BRW_REGISTER_TYPE_F, nir->num_inputs);
      nir_setup_inputs(nir);
   }

   if (nir->num_outputs > 0) {
      nir_outputs = bld.vgrf(BRW_REGISTER_TYPE_F, nir->num_outputs);
      nir_setup_outputs(nir);
   }

   if (nir->num_uniforms > 0) {
      nir_setup_uniforms(nir);
   }

   nir_emit_system_values(nir);

   nir_globals = ralloc_array(mem_ctx, fs_reg, nir->reg_alloc);
   foreach_list_typed(nir_register, reg, node, &nir->registers) {
      unsigned array_elems =
         reg->num_array_elems == 0 ? 1 : reg->num_array_elems;
      unsigned size = array_elems * reg->num_components;
      nir_globals[reg->index] = bld.vgrf(BRW_REGISTER_TYPE_F, size);
   }

   /* get the main function and emit it */
   nir_foreach_overload(nir, overload) {
      assert(strcmp(overload->function->name, "main") == 0);
      assert(overload->impl);
      nir_emit_impl(overload->impl);
   }
}

void
fs_visitor::nir_setup_inputs(nir_shader *shader)
{
   foreach_list_typed(nir_variable, var, node, &shader->inputs) {
      enum brw_reg_type type = brw_type_for_base_type(var->type);
      fs_reg input = offset(nir_inputs, var->data.driver_location);

      fs_reg reg;
      switch (stage) {
      case MESA_SHADER_VERTEX: {
         /* Our ATTR file is indexed by VERT_ATTRIB_*, which is the value
          * stored in nir_variable::location.
          *
          * However, NIR's load_input intrinsics use a different index - an
          * offset into a single contiguous array containing all inputs.
          * This index corresponds to the nir_variable::driver_location field.
          *
          * So, we need to copy from fs_reg(ATTR, var->location) to
          * offset(nir_inputs, var->data.driver_location).
          */
         unsigned components = var->type->without_array()->components();
         unsigned array_length = var->type->is_array() ? var->type->length : 1;
         for (unsigned i = 0; i < array_length; i++) {
            for (unsigned j = 0; j < components; j++) {
               bld.MOV(retype(offset(input, components * i + j), type),
                       offset(fs_reg(ATTR, var->data.location + i, type), j));
            }
         }
         break;
      }
      case MESA_SHADER_GEOMETRY:
      case MESA_SHADER_COMPUTE:
         unreachable("fs_visitor not used for these stages yet.");
         break;
      case MESA_SHADER_FRAGMENT:
         if (var->data.location == VARYING_SLOT_POS) {
            reg = *emit_fragcoord_interpolation(var->data.pixel_center_integer,
                                                var->data.origin_upper_left);
            emit_percomp(bld, fs_inst(BRW_OPCODE_MOV, input, reg), 0xF);
         } else {
            emit_general_interpolation(input, var->name, var->type,
                                       (glsl_interp_qualifier) var->data.interpolation,
                                       var->data.location, var->data.centroid,
                                       var->data.sample);
         }
         break;
      }
   }
}

void
fs_visitor::nir_setup_outputs(nir_shader *shader)
{
   brw_wm_prog_key *key = (brw_wm_prog_key*) this->key;

   foreach_list_typed(nir_variable, var, node, &shader->outputs) {
      fs_reg reg = offset(nir_outputs, var->data.driver_location);

      int vector_elements =
         var->type->is_array() ? var->type->fields.array->vector_elements
                               : var->type->vector_elements;

      if (stage == MESA_SHADER_VERTEX) {
         for (int i = 0; i < ALIGN(type_size(var->type), 4) / 4; i++) {
            int output = var->data.location + i;
            this->outputs[output] = offset(reg, 4 * i);
            this->output_components[output] = vector_elements;
         }
      } else if (var->data.index > 0) {
         assert(var->data.location == FRAG_RESULT_DATA0);
         assert(var->data.index == 1);
         this->dual_src_output = reg;
         this->do_dual_src = true;
      } else if (var->data.location == FRAG_RESULT_COLOR) {
         /* Writing gl_FragColor outputs to all color regions. */
         for (unsigned int i = 0; i < MAX2(key->nr_color_regions, 1); i++) {
            this->outputs[i] = reg;
            this->output_components[i] = 4;
         }
      } else if (var->data.location == FRAG_RESULT_DEPTH) {
         this->frag_depth = reg;
      } else if (var->data.location == FRAG_RESULT_SAMPLE_MASK) {
         this->sample_mask = reg;
      } else {
         /* gl_FragData or a user-defined FS output */
         assert(var->data.location >= FRAG_RESULT_DATA0 &&
                var->data.location < FRAG_RESULT_DATA0 + BRW_MAX_DRAW_BUFFERS);

         /* General color output. */
         for (unsigned int i = 0; i < MAX2(1, var->type->length); i++) {
            int output = var->data.location - FRAG_RESULT_DATA0 + i;
            this->outputs[output] = offset(reg, vector_elements * i);
            this->output_components[output] = vector_elements;
         }
      }
   }
}

void
fs_visitor::nir_setup_uniforms(nir_shader *shader)
{
   uniforms = shader->num_uniforms;
   num_direct_uniforms = shader->num_direct_uniforms;

   /* We split the uniform register file in half.  The first half is
    * entirely direct uniforms.  The second half is indirect.
    */
   param_size[0] = num_direct_uniforms;
   if (shader->num_uniforms > num_direct_uniforms)
      param_size[num_direct_uniforms] = shader->num_uniforms - num_direct_uniforms;

   if (dispatch_width != 8)
      return;

   if (shader_prog) {
      foreach_list_typed(nir_variable, var, node, &shader->uniforms) {
         /* UBO's and atomics don't take up space in the uniform file */
         if (var->interface_type != NULL || var->type->contains_atomic())
            continue;

         if (strncmp(var->name, "gl_", 3) == 0)
            nir_setup_builtin_uniform(var);
         else
            nir_setup_uniform(var);
      }
   } else {
      /* prog_to_nir doesn't create uniform variables; set param up directly. */
      for (unsigned p = 0; p < prog->Parameters->NumParameters; p++) {
         for (unsigned int i = 0; i < 4; i++) {
            stage_prog_data->param[4 * p + i] =
               &prog->Parameters->ParameterValues[p][i];
         }
      }
   }
}

void
fs_visitor::nir_setup_uniform(nir_variable *var)
{
   int namelen = strlen(var->name);

   /* The data for our (non-builtin) uniforms is stored in a series of
      * gl_uniform_driver_storage structs for each subcomponent that
      * glGetUniformLocation() could name.  We know it's been set up in the
      * same order we'd walk the type, so walk the list of storage and find
      * anything with our name, or the prefix of a component that starts with
      * our name.
      */
   unsigned index = var->data.driver_location;
   for (unsigned u = 0; u < shader_prog->NumUniformStorage; u++) {
      struct gl_uniform_storage *storage = &shader_prog->UniformStorage[u];

      if (storage->builtin)
              continue;

      if (strncmp(var->name, storage->name, namelen) != 0 ||
         (storage->name[namelen] != 0 &&
         storage->name[namelen] != '.' &&
         storage->name[namelen] != '[')) {
         continue;
      }

      unsigned slots = storage->type->component_slots();
      if (storage->array_elements)
         slots *= storage->array_elements;

      for (unsigned i = 0; i < slots; i++) {
         stage_prog_data->param[index++] = &storage->storage[i];
      }
   }

   /* Make sure we actually initialized the right amount of stuff here. */
   assert(var->data.driver_location + var->type->component_slots() == index);
}

void
fs_visitor::nir_setup_builtin_uniform(nir_variable *var)
{
   const nir_state_slot *const slots = var->state_slots;
   assert(var->state_slots != NULL);

   unsigned uniform_index = var->data.driver_location;
   for (unsigned int i = 0; i < var->num_state_slots; i++) {
      /* This state reference has already been setup by ir_to_mesa, but we'll
       * get the same index back here.
       */
      int index = _mesa_add_state_reference(this->prog->Parameters,
                                            (gl_state_index *)slots[i].tokens);

      /* Add each of the unique swizzles of the element as a parameter.
       * This'll end up matching the expected layout of the
       * array/matrix/structure we're trying to fill in.
       */
      int last_swiz = -1;
      for (unsigned int j = 0; j < 4; j++) {
         int swiz = GET_SWZ(slots[i].swizzle, j);
         if (swiz == last_swiz)
            break;
         last_swiz = swiz;

         stage_prog_data->param[uniform_index++] =
            &prog->Parameters->ParameterValues[index][swiz];
      }
   }
}

static bool
emit_system_values_block(nir_block *block, void *void_visitor)
{
   fs_visitor *v = (fs_visitor *)void_visitor;
   fs_reg *reg;

   nir_foreach_instr(block, instr) {
      if (instr->type != nir_instr_type_intrinsic)
         continue;

      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
      switch (intrin->intrinsic) {
      case nir_intrinsic_load_vertex_id:
         unreachable("should be lowered by lower_vertex_id().");

      case nir_intrinsic_load_vertex_id_zero_base:
         assert(v->stage == MESA_SHADER_VERTEX);
         reg = &v->nir_system_values[SYSTEM_VALUE_VERTEX_ID_ZERO_BASE];
         if (reg->file == BAD_FILE)
            *reg = *v->emit_vs_system_value(SYSTEM_VALUE_VERTEX_ID_ZERO_BASE);
         break;

      case nir_intrinsic_load_base_vertex:
         assert(v->stage == MESA_SHADER_VERTEX);
         reg = &v->nir_system_values[SYSTEM_VALUE_BASE_VERTEX];
         if (reg->file == BAD_FILE)
            *reg = *v->emit_vs_system_value(SYSTEM_VALUE_BASE_VERTEX);
         break;

      case nir_intrinsic_load_instance_id:
         assert(v->stage == MESA_SHADER_VERTEX);
         reg = &v->nir_system_values[SYSTEM_VALUE_INSTANCE_ID];
         if (reg->file == BAD_FILE)
            *reg = *v->emit_vs_system_value(SYSTEM_VALUE_INSTANCE_ID);
         break;

      case nir_intrinsic_load_sample_pos:
         assert(v->stage == MESA_SHADER_FRAGMENT);
         reg = &v->nir_system_values[SYSTEM_VALUE_SAMPLE_POS];
         if (reg->file == BAD_FILE)
            *reg = *v->emit_samplepos_setup();
         break;

      case nir_intrinsic_load_sample_id:
         assert(v->stage == MESA_SHADER_FRAGMENT);
         reg = &v->nir_system_values[SYSTEM_VALUE_SAMPLE_ID];
         if (reg->file == BAD_FILE)
            *reg = *v->emit_sampleid_setup();
         break;

      case nir_intrinsic_load_sample_mask_in:
         assert(v->stage == MESA_SHADER_FRAGMENT);
         assert(v->devinfo->gen >= 7);
         reg = &v->nir_system_values[SYSTEM_VALUE_SAMPLE_MASK_IN];
         if (reg->file == BAD_FILE)
            *reg = fs_reg(retype(brw_vec8_grf(v->payload.sample_mask_in_reg, 0),
                                 BRW_REGISTER_TYPE_D));
         break;

      default:
         break;
      }
   }

   return true;
}

void
fs_visitor::nir_emit_system_values(nir_shader *shader)
{
   nir_system_values = ralloc_array(mem_ctx, fs_reg, SYSTEM_VALUE_MAX);
   nir_foreach_overload(shader, overload) {
      assert(strcmp(overload->function->name, "main") == 0);
      assert(overload->impl);
      nir_foreach_block(overload->impl, emit_system_values_block, this);
   }
}

void
fs_visitor::nir_emit_impl(nir_function_impl *impl)
{
   nir_locals = reralloc(mem_ctx, nir_locals, fs_reg, impl->reg_alloc);
   foreach_list_typed(nir_register, reg, node, &impl->registers) {
      unsigned array_elems =
         reg->num_array_elems == 0 ? 1 : reg->num_array_elems;
      unsigned size = array_elems * reg->num_components;
      nir_locals[reg->index] = bld.vgrf(BRW_REGISTER_TYPE_F, size);
   }

   nir_emit_cf_list(&impl->body);
}

void
fs_visitor::nir_emit_cf_list(exec_list *list)
{
   exec_list_validate(list);
   foreach_list_typed(nir_cf_node, node, node, list) {
      switch (node->type) {
      case nir_cf_node_if:
         nir_emit_if(nir_cf_node_as_if(node));
         break;

      case nir_cf_node_loop:
         nir_emit_loop(nir_cf_node_as_loop(node));
         break;

      case nir_cf_node_block:
         nir_emit_block(nir_cf_node_as_block(node));
         break;

      default:
         unreachable("Invalid CFG node block");
      }
   }
}

void
fs_visitor::nir_emit_if(nir_if *if_stmt)
{
   /* first, put the condition into f0 */
   fs_inst *inst = bld.MOV(bld.null_reg_d(),
                            retype(get_nir_src(if_stmt->condition),
                                   BRW_REGISTER_TYPE_D));
   inst->conditional_mod = BRW_CONDITIONAL_NZ;

   bld.IF(BRW_PREDICATE_NORMAL);

   nir_emit_cf_list(&if_stmt->then_list);

   /* note: if the else is empty, dead CF elimination will remove it */
   bld.emit(BRW_OPCODE_ELSE);

   nir_emit_cf_list(&if_stmt->else_list);

   bld.emit(BRW_OPCODE_ENDIF);

   if (!try_replace_with_sel() && devinfo->gen < 6) {
      no16("Can't support (non-uniform) control flow on SIMD16\n");
   }
}

void
fs_visitor::nir_emit_loop(nir_loop *loop)
{
   if (devinfo->gen < 6) {
      no16("Can't support (non-uniform) control flow on SIMD16\n");
   }

   bld.emit(BRW_OPCODE_DO);

   nir_emit_cf_list(&loop->body);

   bld.emit(BRW_OPCODE_WHILE);
}

void
fs_visitor::nir_emit_block(nir_block *block)
{
   nir_foreach_instr(block, instr) {
      nir_emit_instr(instr);
   }
}

void
fs_visitor::nir_emit_instr(nir_instr *instr)
{
   const fs_builder abld = bld.annotate(NULL, instr);

   switch (instr->type) {
   case nir_instr_type_alu:
      nir_emit_alu(abld, nir_instr_as_alu(instr));
      break;

   case nir_instr_type_intrinsic:
      nir_emit_intrinsic(abld, nir_instr_as_intrinsic(instr));
      break;

   case nir_instr_type_tex:
      nir_emit_texture(abld, nir_instr_as_tex(instr));
      break;

   case nir_instr_type_load_const:
      /* We can hit these, but we do nothing now and use them as
       * immediates later.
       */
      break;

   case nir_instr_type_jump:
      nir_emit_jump(abld, nir_instr_as_jump(instr));
      break;

   default:
      unreachable("unknown instruction type");
   }
}

static brw_reg_type
brw_type_for_nir_type(nir_alu_type type)
{
   switch (type) {
   case nir_type_unsigned:
      return BRW_REGISTER_TYPE_UD;
   case nir_type_bool:
   case nir_type_int:
      return BRW_REGISTER_TYPE_D;
   case nir_type_float:
      return BRW_REGISTER_TYPE_F;
   default:
      unreachable("unknown type");
   }

   return BRW_REGISTER_TYPE_F;
}

bool
fs_visitor::optimize_frontfacing_ternary(nir_alu_instr *instr,
                                         const fs_reg &result)
{
   if (instr->src[0].src.is_ssa ||
       !instr->src[0].src.reg.reg ||
       !instr->src[0].src.reg.reg->parent_instr)
      return false;

   if (instr->src[0].src.reg.reg->parent_instr->type !=
       nir_instr_type_intrinsic)
      return false;

   nir_intrinsic_instr *src0 =
      nir_instr_as_intrinsic(instr->src[0].src.reg.reg->parent_instr);

   if (src0->intrinsic != nir_intrinsic_load_front_face)
      return false;

   nir_const_value *value1 = nir_src_as_const_value(instr->src[1].src);
   if (!value1 || fabsf(value1->f[0]) != 1.0f)
      return false;

   nir_const_value *value2 = nir_src_as_const_value(instr->src[2].src);
   if (!value2 || fabsf(value2->f[0]) != 1.0f)
      return false;

   fs_reg tmp = vgrf(glsl_type::int_type);

   if (devinfo->gen >= 6) {
      /* Bit 15 of g0.0 is 0 if the polygon is front facing. */
      fs_reg g0 = fs_reg(retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_W));

      /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
       *
       *    or(8)  tmp.1<2>W  g0.0<0,1,0>W  0x00003f80W
       *    and(8) dst<1>D    tmp<8,8,1>D   0xbf800000D
       *
       * and negate g0.0<0,1,0>W for (gl_FrontFacing ? -1.0 : 1.0).
       *
       * This negation looks like it's safe in practice, because bits 0:4 will
       * surely be TRIANGLES
       */

      if (value1->f[0] == -1.0f) {
         g0.negate = true;
      }

      tmp.type = BRW_REGISTER_TYPE_W;
      tmp.subreg_offset = 2;
      tmp.stride = 2;

      fs_inst *or_inst = bld.OR(tmp, g0, fs_reg(0x3f80));
      or_inst->src[1].type = BRW_REGISTER_TYPE_UW;

      tmp.type = BRW_REGISTER_TYPE_D;
      tmp.subreg_offset = 0;
      tmp.stride = 1;
   } else {
      /* Bit 31 of g1.6 is 0 if the polygon is front facing. */
      fs_reg g1_6 = fs_reg(retype(brw_vec1_grf(1, 6), BRW_REGISTER_TYPE_D));

      /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
       *
       *    or(8)  tmp<1>D  g1.6<0,1,0>D  0x3f800000D
       *    and(8) dst<1>D  tmp<8,8,1>D   0xbf800000D
       *
       * and negate g1.6<0,1,0>D for (gl_FrontFacing ? -1.0 : 1.0).
       *
       * This negation looks like it's safe in practice, because bits 0:4 will
       * surely be TRIANGLES
       */

      if (value1->f[0] == -1.0f) {
         g1_6.negate = true;
      }

      bld.OR(tmp, g1_6, fs_reg(0x3f800000));
   }
   bld.AND(retype(result, BRW_REGISTER_TYPE_D), tmp, fs_reg(0xbf800000));

   return true;
}

void
fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
{
   struct brw_wm_prog_key *fs_key = (struct brw_wm_prog_key *) this->key;
   fs_inst *inst;

   fs_reg result = get_nir_dest(instr->dest.dest);
   result.type = brw_type_for_nir_type(nir_op_infos[instr->op].output_type);

   fs_reg op[4];
   for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
      op[i] = get_nir_src(instr->src[i].src);
      op[i].type = brw_type_for_nir_type(nir_op_infos[instr->op].input_types[i]);
      op[i].abs = instr->src[i].abs;
      op[i].negate = instr->src[i].negate;
   }

   /* We get a bunch of mov's out of the from_ssa pass and they may still
    * be vectorized.  We'll handle them as a special-case.  We'll also
    * handle vecN here because it's basically the same thing.
    */
   switch (instr->op) {
   case nir_op_imov:
   case nir_op_fmov:
   case nir_op_vec2:
   case nir_op_vec3:
   case nir_op_vec4: {
      fs_reg temp = result;
      bool need_extra_copy = false;
      for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
         if (!instr->src[i].src.is_ssa &&
             instr->dest.dest.reg.reg == instr->src[i].src.reg.reg) {
            need_extra_copy = true;
            temp = bld.vgrf(result.type, 4);
            break;
         }
      }

      for (unsigned i = 0; i < 4; i++) {
         if (!(instr->dest.write_mask & (1 << i)))
            continue;

         if (instr->op == nir_op_imov || instr->op == nir_op_fmov) {
            inst = bld.MOV(offset(temp, i),
                           offset(op[0], instr->src[0].swizzle[i]));
         } else {
            inst = bld.MOV(offset(temp, i),
                           offset(op[i], instr->src[i].swizzle[0]));
         }
         inst->saturate = instr->dest.saturate;
      }

      /* In this case the source and destination registers were the same,
       * so we need to insert an extra set of moves in order to deal with
       * any swizzling.
       */
      if (need_extra_copy) {
         for (unsigned i = 0; i < 4; i++) {
            if (!(instr->dest.write_mask & (1 << i)))
               continue;

            bld.MOV(offset(result, i), offset(temp, i));
         }
      }
      return;
   }
   default:
      break;
   }

   /* At this point, we have dealt with any instruction that operates on
    * more than a single channel.  Therefore, we can just adjust the source
    * and destination registers for that channel and emit the instruction.
    */
   unsigned channel = 0;
   if (nir_op_infos[instr->op].output_size == 0) {
      /* Since NIR is doing the scalarizing for us, we should only ever see
       * vectorized operations with a single channel.
       */
      assert(_mesa_bitcount(instr->dest.write_mask) == 1);
      channel = ffs(instr->dest.write_mask) - 1;

      result = offset(result, channel);
   }

   for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
      assert(nir_op_infos[instr->op].input_sizes[i] < 2);
      op[i] = offset(op[i], instr->src[i].swizzle[channel]);
   }

   switch (instr->op) {
   case nir_op_i2f:
   case nir_op_u2f:
      inst = bld.MOV(result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_f2i:
   case nir_op_f2u:
      bld.MOV(result, op[0]);
      break;

   case nir_op_fsign: {
      /* AND(val, 0x80000000) gives the sign bit.
         *
         * Predicated OR ORs 1.0 (0x3f800000) with the sign bit if val is not
         * zero.
         */
      bld.CMP(bld.null_reg_f(), op[0], fs_reg(0.0f), BRW_CONDITIONAL_NZ);

      fs_reg result_int = retype(result, BRW_REGISTER_TYPE_UD);
      op[0].type = BRW_REGISTER_TYPE_UD;
      result.type = BRW_REGISTER_TYPE_UD;
      bld.AND(result_int, op[0], fs_reg(0x80000000u));

      inst = bld.OR(result_int, result_int, fs_reg(0x3f800000u));
      inst->predicate = BRW_PREDICATE_NORMAL;
      if (instr->dest.saturate) {
         inst = bld.MOV(result, result);
         inst->saturate = true;
      }
      break;
   }

   case nir_op_isign:
      /*  ASR(val, 31) -> negative val generates 0xffffffff (signed -1).
       *               -> non-negative val generates 0x00000000.
       *  Predicated OR sets 1 if val is positive.
       */
      bld.CMP(bld.null_reg_d(), op[0], fs_reg(0), BRW_CONDITIONAL_G);
      bld.ASR(result, op[0], fs_reg(31));
      inst = bld.OR(result, result, fs_reg(1));
      inst->predicate = BRW_PREDICATE_NORMAL;
      break;

   case nir_op_frcp:
      inst = bld.emit(SHADER_OPCODE_RCP, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fexp2:
      inst = bld.emit(SHADER_OPCODE_EXP2, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_flog2:
      inst = bld.emit(SHADER_OPCODE_LOG2, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fsin:
      inst = bld.emit(SHADER_OPCODE_SIN, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fcos:
      inst = bld.emit(SHADER_OPCODE_COS, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fddx:
      if (fs_key->high_quality_derivatives) {
         inst = bld.emit(FS_OPCODE_DDX_FINE, result, op[0]);
      } else {
         inst = bld.emit(FS_OPCODE_DDX_COARSE, result, op[0]);
      }
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fddx_fine:
      inst = bld.emit(FS_OPCODE_DDX_FINE, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fddx_coarse:
      inst = bld.emit(FS_OPCODE_DDX_COARSE, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fddy:
      if (fs_key->high_quality_derivatives) {
         inst = bld.emit(FS_OPCODE_DDY_FINE, result, op[0],
                         fs_reg(fs_key->render_to_fbo));
      } else {
         inst = bld.emit(FS_OPCODE_DDY_COARSE, result, op[0],
                         fs_reg(fs_key->render_to_fbo));
      }
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fddy_fine:
      inst = bld.emit(FS_OPCODE_DDY_FINE, result, op[0],
                      fs_reg(fs_key->render_to_fbo));
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fddy_coarse:
      inst = bld.emit(FS_OPCODE_DDY_COARSE, result, op[0],
                      fs_reg(fs_key->render_to_fbo));
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fadd:
   case nir_op_iadd:
      inst = bld.ADD(result, op[0], op[1]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fmul:
      inst = bld.MUL(result, op[0], op[1]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_imul:
      bld.MUL(result, op[0], op[1]);
      break;

   case nir_op_imul_high:
   case nir_op_umul_high: {
      if (devinfo->gen >= 7)
         no16("SIMD16 explicit accumulator operands unsupported\n");

      struct brw_reg acc = retype(brw_acc_reg(dispatch_width), result.type);

      fs_inst *mul = bld.MUL(acc, op[0], op[1]);
      bld.MACH(result, op[0], op[1]);

      /* Until Gen8, integer multiplies read 32-bits from one source, and
       * 16-bits from the other, and relying on the MACH instruction to
       * generate the high bits of the result.
       *
       * On Gen8, the multiply instruction does a full 32x32-bit multiply,
       * but in order to do a 64x64-bit multiply we have to simulate the
       * previous behavior and then use a MACH instruction.
       *
       * FINISHME: Don't use source modifiers on src1.
       */
      if (devinfo->gen >= 8) {
         assert(mul->src[1].type == BRW_REGISTER_TYPE_D ||
                mul->src[1].type == BRW_REGISTER_TYPE_UD);
         if (mul->src[1].type == BRW_REGISTER_TYPE_D) {
            mul->src[1].type = BRW_REGISTER_TYPE_W;
            mul->src[1].stride = 2;
         } else {
            mul->src[1].type = BRW_REGISTER_TYPE_UW;
            mul->src[1].stride = 2;
         }
      }
      break;
   }

   case nir_op_idiv:
   case nir_op_udiv:
      bld.emit(SHADER_OPCODE_INT_QUOTIENT, result, op[0], op[1]);
      break;

   case nir_op_uadd_carry: {
      if (devinfo->gen >= 7)
         no16("SIMD16 explicit accumulator operands unsupported\n");

      struct brw_reg acc = retype(brw_acc_reg(dispatch_width),
                                  BRW_REGISTER_TYPE_UD);

      bld.ADDC(bld.null_reg_ud(), op[0], op[1]);
      bld.MOV(result, fs_reg(acc));
      break;
   }

   case nir_op_usub_borrow: {
      if (devinfo->gen >= 7)
         no16("SIMD16 explicit accumulator operands unsupported\n");

      struct brw_reg acc = retype(brw_acc_reg(dispatch_width),
                                  BRW_REGISTER_TYPE_UD);

      bld.SUBB(bld.null_reg_ud(), op[0], op[1]);
      bld.MOV(result, fs_reg(acc));
      break;
   }

   case nir_op_umod:
      bld.emit(SHADER_OPCODE_INT_REMAINDER, result, op[0], op[1]);
      break;

   case nir_op_flt:
   case nir_op_ilt:
   case nir_op_ult:
      bld.CMP(result, op[0], op[1], BRW_CONDITIONAL_L);
      break;

   case nir_op_fge:
   case nir_op_ige:
   case nir_op_uge:
      bld.CMP(result, op[0], op[1], BRW_CONDITIONAL_GE);
      break;

   case nir_op_feq:
   case nir_op_ieq:
      bld.CMP(result, op[0], op[1], BRW_CONDITIONAL_Z);
      break;

   case nir_op_fne:
   case nir_op_ine:
      bld.CMP(result, op[0], op[1], BRW_CONDITIONAL_NZ);
      break;

   case nir_op_inot:
      if (devinfo->gen >= 8) {
         resolve_source_modifiers(&op[0]);
      }
      bld.NOT(result, op[0]);
      break;
   case nir_op_ixor:
      if (devinfo->gen >= 8) {
         resolve_source_modifiers(&op[0]);
         resolve_source_modifiers(&op[1]);
      }
      bld.XOR(result, op[0], op[1]);
      break;
   case nir_op_ior:
      if (devinfo->gen >= 8) {
         resolve_source_modifiers(&op[0]);
         resolve_source_modifiers(&op[1]);
      }
      bld.OR(result, op[0], op[1]);
      break;
   case nir_op_iand:
      if (devinfo->gen >= 8) {
         resolve_source_modifiers(&op[0]);
         resolve_source_modifiers(&op[1]);
      }
      bld.AND(result, op[0], op[1]);
      break;

   case nir_op_fdot2:
   case nir_op_fdot3:
   case nir_op_fdot4:
   case nir_op_bany2:
   case nir_op_bany3:
   case nir_op_bany4:
   case nir_op_ball2:
   case nir_op_ball3:
   case nir_op_ball4:
   case nir_op_ball_fequal2:
   case nir_op_ball_iequal2:
   case nir_op_ball_fequal3:
   case nir_op_ball_iequal3:
   case nir_op_ball_fequal4:
   case nir_op_ball_iequal4:
   case nir_op_bany_fnequal2:
   case nir_op_bany_inequal2:
   case nir_op_bany_fnequal3:
   case nir_op_bany_inequal3:
   case nir_op_bany_fnequal4:
   case nir_op_bany_inequal4:
      unreachable("Lowered by nir_lower_alu_reductions");

   case nir_op_fnoise1_1:
   case nir_op_fnoise1_2:
   case nir_op_fnoise1_3:
   case nir_op_fnoise1_4:
   case nir_op_fnoise2_1:
   case nir_op_fnoise2_2:
   case nir_op_fnoise2_3:
   case nir_op_fnoise2_4:
   case nir_op_fnoise3_1:
   case nir_op_fnoise3_2:
   case nir_op_fnoise3_3:
   case nir_op_fnoise3_4:
   case nir_op_fnoise4_1:
   case nir_op_fnoise4_2:
   case nir_op_fnoise4_3:
   case nir_op_fnoise4_4:
      unreachable("not reached: should be handled by lower_noise");

   case nir_op_ldexp:
      unreachable("not reached: should be handled by ldexp_to_arith()");

   case nir_op_fsqrt:
      inst = bld.emit(SHADER_OPCODE_SQRT, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_frsq:
      inst = bld.emit(SHADER_OPCODE_RSQ, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_b2i:
      bld.AND(result, op[0], fs_reg(1));
      break;
   case nir_op_b2f:
      bld.AND(retype(result, BRW_REGISTER_TYPE_UD), op[0], fs_reg(0x3f800000u));
      break;

   case nir_op_f2b:
      bld.CMP(result, op[0], fs_reg(0.0f), BRW_CONDITIONAL_NZ);
      break;
   case nir_op_i2b:
      bld.CMP(result, op[0], fs_reg(0), BRW_CONDITIONAL_NZ);
      break;

   case nir_op_ftrunc:
      inst = bld.RNDZ(result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fceil: {
      op[0].negate = !op[0].negate;
      fs_reg temp = vgrf(glsl_type::float_type);
      bld.RNDD(temp, op[0]);
      temp.negate = true;
      inst = bld.MOV(result, temp);
      inst->saturate = instr->dest.saturate;
      break;
   }
   case nir_op_ffloor:
      inst = bld.RNDD(result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_ffract:
      inst = bld.FRC(result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_fround_even:
      inst = bld.RNDE(result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fmin:
   case nir_op_imin:
   case nir_op_umin:
      if (devinfo->gen >= 6) {
         inst = bld.emit(BRW_OPCODE_SEL, result, op[0], op[1]);
         inst->conditional_mod = BRW_CONDITIONAL_L;
      } else {
         bld.CMP(bld.null_reg_d(), op[0], op[1], BRW_CONDITIONAL_L);
         inst = bld.SEL(result, op[0], op[1]);
         inst->predicate = BRW_PREDICATE_NORMAL;
      }
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fmax:
   case nir_op_imax:
   case nir_op_umax:
      if (devinfo->gen >= 6) {
         inst = bld.emit(BRW_OPCODE_SEL, result, op[0], op[1]);
         inst->conditional_mod = BRW_CONDITIONAL_GE;
      } else {
         bld.CMP(bld.null_reg_d(), op[0], op[1], BRW_CONDITIONAL_GE);
         inst = bld.SEL(result, op[0], op[1]);
         inst->predicate = BRW_PREDICATE_NORMAL;
      }
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_pack_snorm_2x16:
   case nir_op_pack_snorm_4x8:
   case nir_op_pack_unorm_2x16:
   case nir_op_pack_unorm_4x8:
   case nir_op_unpack_snorm_2x16:
   case nir_op_unpack_snorm_4x8:
   case nir_op_unpack_unorm_2x16:
   case nir_op_unpack_unorm_4x8:
   case nir_op_unpack_half_2x16:
   case nir_op_pack_half_2x16:
      unreachable("not reached: should be handled by lower_packing_builtins");

   case nir_op_unpack_half_2x16_split_x:
      inst = bld.emit(FS_OPCODE_UNPACK_HALF_2x16_SPLIT_X, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;
   case nir_op_unpack_half_2x16_split_y:
      inst = bld.emit(FS_OPCODE_UNPACK_HALF_2x16_SPLIT_Y, result, op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_fpow:
      inst = bld.emit(SHADER_OPCODE_POW, result, op[0], op[1]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_bitfield_reverse:
      bld.BFREV(result, op[0]);
      break;

   case nir_op_bit_count:
      bld.CBIT(result, op[0]);
      break;

   case nir_op_ufind_msb:
   case nir_op_ifind_msb: {
      bld.FBH(retype(result, BRW_REGISTER_TYPE_UD), op[0]);

      /* FBH counts from the MSB side, while GLSL's findMSB() wants the count
       * from the LSB side. If FBH didn't return an error (0xFFFFFFFF), then
       * subtract the result from 31 to convert the MSB count into an LSB count.
       */

      bld.CMP(bld.null_reg_d(), result, fs_reg(-1), BRW_CONDITIONAL_NZ);
      fs_reg neg_result(result);
      neg_result.negate = true;
      inst = bld.ADD(result, neg_result, fs_reg(31));
      inst->predicate = BRW_PREDICATE_NORMAL;
      break;
   }

   case nir_op_find_lsb:
      bld.FBL(result, op[0]);
      break;

   case nir_op_ubitfield_extract:
   case nir_op_ibitfield_extract:
      bld.BFE(result, op[2], op[1], op[0]);
      break;
   case nir_op_bfm:
      bld.BFI1(result, op[0], op[1]);
      break;
   case nir_op_bfi:
      bld.BFI2(result, op[0], op[1], op[2]);
      break;

   case nir_op_bitfield_insert:
      unreachable("not reached: should be handled by "
                  "lower_instructions::bitfield_insert_to_bfm_bfi");

   case nir_op_ishl:
      bld.SHL(result, op[0], op[1]);
      break;
   case nir_op_ishr:
      bld.ASR(result, op[0], op[1]);
      break;
   case nir_op_ushr:
      bld.SHR(result, op[0], op[1]);
      break;

   case nir_op_pack_half_2x16_split:
      bld.emit(FS_OPCODE_PACK_HALF_2x16_SPLIT, result, op[0], op[1]);
      break;

   case nir_op_ffma:
      inst = bld.MAD(result, op[2], op[1], op[0]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_flrp:
      inst = bld.LRP(result, op[0], op[1], op[2]);
      inst->saturate = instr->dest.saturate;
      break;

   case nir_op_bcsel:
      if (optimize_frontfacing_ternary(instr, result))
         return;

      bld.CMP(bld.null_reg_d(), op[0], fs_reg(0), BRW_CONDITIONAL_NZ);
      inst = bld.SEL(result, op[1], op[2]);
      inst->predicate = BRW_PREDICATE_NORMAL;
      break;

   default:
      unreachable("unhandled instruction");
   }

   /* If we need to do a boolean resolve, replace the result with -(x & 1)
    * to sign extend the low bit to 0/~0
    */
   if (devinfo->gen <= 5 &&
       (instr->instr.pass_flags & BRW_NIR_BOOLEAN_MASK) == BRW_NIR_BOOLEAN_NEEDS_RESOLVE) {
      fs_reg masked = vgrf(glsl_type::int_type);
      bld.AND(masked, result, fs_reg(1));
      masked.negate = true;
      bld.MOV(retype(result, BRW_REGISTER_TYPE_D), masked);
   }
}

static fs_reg
fs_reg_for_nir_reg(fs_visitor *v, nir_register *nir_reg,
                   unsigned base_offset, nir_src *indirect)
{
   fs_reg reg;
   if (nir_reg->is_global)
      reg = v->nir_globals[nir_reg->index];
   else
      reg = v->nir_locals[nir_reg->index];

   reg = offset(reg, base_offset * nir_reg->num_components);
   if (indirect) {
      int multiplier = nir_reg->num_components * (v->dispatch_width / 8);

      reg.reladdr = new(v->mem_ctx) fs_reg(v->vgrf(glsl_type::int_type));
      v->bld.MUL(*reg.reladdr, v->get_nir_src(*indirect),
                 fs_reg(multiplier));
   }

   return reg;
}

fs_reg
fs_visitor::get_nir_src(nir_src src)
{
   if (src.is_ssa) {
      assert(src.ssa->parent_instr->type == nir_instr_type_load_const);
      nir_load_const_instr *load = nir_instr_as_load_const(src.ssa->parent_instr);
      fs_reg reg = bld.vgrf(BRW_REGISTER_TYPE_D, src.ssa->num_components);

      for (unsigned i = 0; i < src.ssa->num_components; ++i)
         bld.MOV(offset(reg, i), fs_reg(load->value.i[i]));

      return reg;
   } else {
      fs_reg reg = fs_reg_for_nir_reg(this, src.reg.reg, src.reg.base_offset,
                                      src.reg.indirect);

      /* to avoid floating-point denorm flushing problems, set the type by
       * default to D - instructions that need floating point semantics will set
       * this to F if they need to
       */
      return retype(reg, BRW_REGISTER_TYPE_D);
   }
}

fs_reg
fs_visitor::get_nir_dest(nir_dest dest)
{
   return fs_reg_for_nir_reg(this, dest.reg.reg, dest.reg.base_offset,
                             dest.reg.indirect);
}

void
fs_visitor::emit_percomp(const fs_builder &bld, const fs_inst &inst,
                         unsigned wr_mask)
{
   for (unsigned i = 0; i < 4; i++) {
      if (!((wr_mask >> i) & 1))
         continue;

      fs_inst *new_inst = new(mem_ctx) fs_inst(inst);
      new_inst->dst = offset(new_inst->dst, i);
      for (unsigned j = 0; j < new_inst->sources; j++)
         if (new_inst->src[j].file == GRF)
            new_inst->src[j] = offset(new_inst->src[j], i);

      bld.emit(new_inst);
   }
}

void
fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr)
{
   fs_reg dest;
   if (nir_intrinsic_infos[instr->intrinsic].has_dest)
      dest = get_nir_dest(instr->dest);

   bool has_indirect = false;

   switch (instr->intrinsic) {
   case nir_intrinsic_discard:
   case nir_intrinsic_discard_if: {
      /* We track our discarded pixels in f0.1.  By predicating on it, we can
       * update just the flag bits that aren't yet discarded.  If there's no
       * condition, we emit a CMP of g0 != g0, so all currently executing
       * channels will get turned off.
       */
      fs_inst *cmp;
      if (instr->intrinsic == nir_intrinsic_discard_if) {
         cmp = bld.CMP(bld.null_reg_f(), get_nir_src(instr->src[0]),
                       fs_reg(0), BRW_CONDITIONAL_Z);
      } else {
         fs_reg some_reg = fs_reg(retype(brw_vec8_grf(0, 0),
                                       BRW_REGISTER_TYPE_UW));
         cmp = bld.CMP(bld.null_reg_f(), some_reg, some_reg, BRW_CONDITIONAL_NZ);
      }
      cmp->predicate = BRW_PREDICATE_NORMAL;
      cmp->flag_subreg = 1;

      if (devinfo->gen >= 6) {
         emit_discard_jump();
      }
      break;
   }

   case nir_intrinsic_atomic_counter_inc:
   case nir_intrinsic_atomic_counter_dec:
   case nir_intrinsic_atomic_counter_read: {
      unsigned surf_index = prog_data->binding_table.abo_start +
                            (unsigned) instr->const_index[0];
      fs_reg offset = fs_reg(get_nir_src(instr->src[0]));

      switch (instr->intrinsic) {
         case nir_intrinsic_atomic_counter_inc:
            emit_untyped_atomic(BRW_AOP_INC, surf_index, dest, offset,
                                fs_reg(), fs_reg());
            break;
         case nir_intrinsic_atomic_counter_dec:
            emit_untyped_atomic(BRW_AOP_PREDEC, surf_index, dest, offset,
                                fs_reg(), fs_reg());
            break;
         case nir_intrinsic_atomic_counter_read:
            emit_untyped_surface_read(surf_index, dest, offset);
            break;
         default:
            unreachable("Unreachable");
      }
      break;
   }

   case nir_intrinsic_load_front_face:
      bld.MOV(retype(dest, BRW_REGISTER_TYPE_D),
              *emit_frontfacing_interpolation());
      break;

   case nir_intrinsic_load_vertex_id:
      unreachable("should be lowered by lower_vertex_id()");

   case nir_intrinsic_load_vertex_id_zero_base: {
      fs_reg vertex_id = nir_system_values[SYSTEM_VALUE_VERTEX_ID_ZERO_BASE];
      assert(vertex_id.file != BAD_FILE);
      dest.type = vertex_id.type;
      bld.MOV(dest, vertex_id);
      break;
   }

   case nir_intrinsic_load_base_vertex: {
      fs_reg base_vertex = nir_system_values[SYSTEM_VALUE_BASE_VERTEX];
      assert(base_vertex.file != BAD_FILE);
      dest.type = base_vertex.type;
      bld.MOV(dest, base_vertex);
      break;
   }

   case nir_intrinsic_load_instance_id: {
      fs_reg instance_id = nir_system_values[SYSTEM_VALUE_INSTANCE_ID];
      assert(instance_id.file != BAD_FILE);
      dest.type = instance_id.type;
      bld.MOV(dest, instance_id);
      break;
   }

   case nir_intrinsic_load_sample_mask_in: {
      fs_reg sample_mask_in = nir_system_values[SYSTEM_VALUE_SAMPLE_MASK_IN];
      assert(sample_mask_in.file != BAD_FILE);
      dest.type = sample_mask_in.type;
      bld.MOV(dest, sample_mask_in);
      break;
   }

   case nir_intrinsic_load_sample_pos: {
      fs_reg sample_pos = nir_system_values[SYSTEM_VALUE_SAMPLE_POS];
      assert(sample_pos.file != BAD_FILE);
      dest.type = sample_pos.type;
      bld.MOV(dest, sample_pos);
      bld.MOV(offset(dest, 1), offset(sample_pos, 1));
      break;
   }

   case nir_intrinsic_load_sample_id: {
      fs_reg sample_id = nir_system_values[SYSTEM_VALUE_SAMPLE_ID];
      assert(sample_id.file != BAD_FILE);
      dest.type = sample_id.type;
      bld.MOV(dest, sample_id);
      break;
   }

   case nir_intrinsic_load_uniform_indirect:
      has_indirect = true;
      /* fallthrough */
   case nir_intrinsic_load_uniform: {
      unsigned index = instr->const_index[0];

      fs_reg uniform_reg;
      if (index < num_direct_uniforms) {
         uniform_reg = fs_reg(UNIFORM, 0);
      } else {
         uniform_reg = fs_reg(UNIFORM, num_direct_uniforms);
         index -= num_direct_uniforms;
      }

      for (unsigned j = 0; j < instr->num_components; j++) {
         fs_reg src = offset(retype(uniform_reg, dest.type), index);
         if (has_indirect)
            src.reladdr = new(mem_ctx) fs_reg(get_nir_src(instr->src[0]));
         index++;

         bld.MOV(dest, src);
         dest = offset(dest, 1);
      }
      break;
   }

   case nir_intrinsic_load_ubo_indirect:
      has_indirect = true;
      /* fallthrough */
   case nir_intrinsic_load_ubo: {
      nir_const_value *const_index = nir_src_as_const_value(instr->src[0]);
      fs_reg surf_index;

      if (const_index) {
         surf_index = fs_reg(stage_prog_data->binding_table.ubo_start +
                             const_index->u[0]);
      } else {
         /* The block index is not a constant. Evaluate the index expression
          * per-channel and add the base UBO index; we have to select a value
          * from any live channel.
          */
         surf_index = vgrf(glsl_type::uint_type);
         bld.ADD(surf_index, get_nir_src(instr->src[0]),
                 fs_reg(stage_prog_data->binding_table.ubo_start));
         bld.emit_uniformize(surf_index, surf_index);

         /* Assume this may touch any UBO. It would be nice to provide
          * a tighter bound, but the array information is already lowered away.
          */
         brw_mark_surface_used(prog_data,
                               stage_prog_data->binding_table.ubo_start +
                               shader_prog->NumUniformBlocks - 1);
      }

      if (has_indirect) {
         /* Turn the byte offset into a dword offset. */
         fs_reg base_offset = vgrf(glsl_type::int_type);
         bld.SHR(base_offset, retype(get_nir_src(instr->src[1]),
                                     BRW_REGISTER_TYPE_D),
                 fs_reg(2));

         unsigned vec4_offset = instr->const_index[0] / 4;
         for (int i = 0; i < instr->num_components; i++)
            VARYING_PULL_CONSTANT_LOAD(bld, offset(dest, i), surf_index,
                                       base_offset, vec4_offset + i);
      } else {
         fs_reg packed_consts = vgrf(glsl_type::float_type);
         packed_consts.type = dest.type;

         fs_reg const_offset_reg((unsigned) instr->const_index[0] & ~15);
         bld.emit(FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD, packed_consts,
                  surf_index, const_offset_reg);

         for (unsigned i = 0; i < instr->num_components; i++) {
            packed_consts.set_smear(instr->const_index[0] % 16 / 4 + i);

            /* The std140 packing rules don't allow vectors to cross 16-byte
             * boundaries, and a reg is 32 bytes.
             */
            assert(packed_consts.subreg_offset < 32);

            bld.MOV(dest, packed_consts);
            dest = offset(dest, 1);
         }
      }
      break;
   }

   case nir_intrinsic_load_input_indirect:
      has_indirect = true;
      /* fallthrough */
   case nir_intrinsic_load_input: {
      unsigned index = 0;
      for (unsigned j = 0; j < instr->num_components; j++) {
         fs_reg src = offset(retype(nir_inputs, dest.type),
                             instr->const_index[0] + index);
         if (has_indirect)
            src.reladdr = new(mem_ctx) fs_reg(get_nir_src(instr->src[0]));
         index++;

         bld.MOV(dest, src);
         dest = offset(dest, 1);
      }
      break;
   }

   /* Handle ARB_gpu_shader5 interpolation intrinsics
    *
    * It's worth a quick word of explanation as to why we handle the full
    * variable-based interpolation intrinsic rather than a lowered version
    * with like we do for other inputs.  We have to do that because the way
    * we set up inputs doesn't allow us to use the already setup inputs for
    * interpolation.  At the beginning of the shader, we go through all of
    * the input variables and do the initial interpolation and put it in
    * the nir_inputs array based on its location as determined in
    * nir_lower_io.  If the input isn't used, dead code cleans up and
    * everything works fine.  However, when we get to the ARB_gpu_shader5
    * interpolation intrinsics, we need to reinterpolate the input
    * differently.  If we used an intrinsic that just had an index it would
    * only give us the offset into the nir_inputs array.  However, this is
    * useless because that value is post-interpolation and we need
    * pre-interpolation.  In order to get the actual location of the bits
    * we get from the vertex fetching hardware, we need the variable.
    */
   case nir_intrinsic_interp_var_at_centroid:
   case nir_intrinsic_interp_var_at_sample:
   case nir_intrinsic_interp_var_at_offset: {
      /* in SIMD16 mode, the pixel interpolator returns coords interleaved
       * 8 channels at a time, same as the barycentric coords presented in
       * the FS payload. this requires a bit of extra work to support.
       */
      no16("interpolate_at_* not yet supported in SIMD16 mode.");

      fs_reg dst_xy = bld.vgrf(BRW_REGISTER_TYPE_F, 2);

      /* For most messages, we need one reg of ignored data; the hardware
       * requires mlen==1 even when there is no payload. in the per-slot
       * offset case, we'll replace this with the proper source data.
       */
      fs_reg src = vgrf(glsl_type::float_type);
      int mlen = 1;     /* one reg unless overriden */
      fs_inst *inst;

      switch (instr->intrinsic) {
      case nir_intrinsic_interp_var_at_centroid:
         inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_CENTROID,
                         dst_xy, src, fs_reg(0u));
         break;

      case nir_intrinsic_interp_var_at_sample: {
         /* XXX: We should probably handle non-constant sample id's */
         nir_const_value *const_sample = nir_src_as_const_value(instr->src[0]);
         assert(const_sample);
         unsigned msg_data = const_sample ? const_sample->i[0] << 4 : 0;
         inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_SAMPLE, dst_xy, src,
                         fs_reg(msg_data));
         break;
      }

      case nir_intrinsic_interp_var_at_offset: {
         nir_const_value *const_offset = nir_src_as_const_value(instr->src[0]);

         if (const_offset) {
            unsigned off_x = MIN2((int)(const_offset->f[0] * 16), 7) & 0xf;
            unsigned off_y = MIN2((int)(const_offset->f[1] * 16), 7) & 0xf;

            inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_SHARED_OFFSET, dst_xy, src,
                            fs_reg(off_x | (off_y << 4)));
         } else {
            src = vgrf(glsl_type::ivec2_type);
            fs_reg offset_src = retype(get_nir_src(instr->src[0]),
                                       BRW_REGISTER_TYPE_F);
            for (int i = 0; i < 2; i++) {
               fs_reg temp = vgrf(glsl_type::float_type);
               bld.MUL(temp, offset(offset_src, i), fs_reg(16.0f));
               fs_reg itemp = vgrf(glsl_type::int_type);
               bld.MOV(itemp, temp);  /* float to int */

               /* Clamp the upper end of the range to +7/16.
                * ARB_gpu_shader5 requires that we support a maximum offset
                * of +0.5, which isn't representable in a S0.4 value -- if
                * we didn't clamp it, we'd end up with -8/16, which is the
                * opposite of what the shader author wanted.
                *
                * This is legal due to ARB_gpu_shader5's quantization
                * rules:
                *
                * "Not all values of <offset> may be supported; x and y
                * offsets may be rounded to fixed-point values with the
                * number of fraction bits given by the
                * implementation-dependent constant
                * FRAGMENT_INTERPOLATION_OFFSET_BITS"
                */
               set_condmod(BRW_CONDITIONAL_L,
                           bld.SEL(offset(src, i), itemp, fs_reg(7)));
            }

            mlen = 2;
            inst = bld.emit(FS_OPCODE_INTERPOLATE_AT_PER_SLOT_OFFSET, dst_xy, src,
                            fs_reg(0u));
         }
         break;
      }

      default:
         unreachable("Invalid intrinsic");
      }

      inst->mlen = mlen;
      inst->regs_written = 2; /* 2 floats per slot returned */
      inst->pi_noperspective = instr->variables[0]->var->data.interpolation ==
                               INTERP_QUALIFIER_NOPERSPECTIVE;

      for (unsigned j = 0; j < instr->num_components; j++) {
         fs_reg src = interp_reg(instr->variables[0]->var->data.location, j);
         src.type = dest.type;

         bld.emit(FS_OPCODE_LINTERP, dest, dst_xy, src);
         dest = offset(dest, 1);
      }
      break;
   }

   case nir_intrinsic_store_output_indirect:
      has_indirect = true;
      /* fallthrough */
   case nir_intrinsic_store_output: {
      fs_reg src = get_nir_src(instr->src[0]);
      unsigned index = 0;
      for (unsigned j = 0; j < instr->num_components; j++) {
         fs_reg new_dest = offset(retype(nir_outputs, src.type),
                                  instr->const_index[0] + index);
         if (has_indirect)
            src.reladdr = new(mem_ctx) fs_reg(get_nir_src(instr->src[1]));
         index++;
         bld.MOV(new_dest, src);
         src = offset(src, 1);
      }
      break;
   }

   default:
      unreachable("unknown intrinsic");
   }
}

void
fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
{
   unsigned sampler = instr->sampler_index;
   fs_reg sampler_reg(sampler);

   /* FINISHME: We're failing to recompile our programs when the sampler is
    * updated.  This only matters for the texture rectangle scale parameters
    * (pre-gen6, or gen6+ with GL_CLAMP).
    */
   int texunit = prog->SamplerUnits[sampler];

   int gather_component = instr->component;

   bool is_rect = instr->sampler_dim == GLSL_SAMPLER_DIM_RECT;

   bool is_cube_array = instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE &&
                        instr->is_array;

   int lod_components = 0, offset_components = 0;

   fs_reg coordinate, shadow_comparitor, lod, lod2, sample_index, mcs, tex_offset;

   for (unsigned i = 0; i < instr->num_srcs; i++) {
      fs_reg src = get_nir_src(instr->src[i].src);
      switch (instr->src[i].src_type) {
      case nir_tex_src_bias:
         lod = retype(src, BRW_REGISTER_TYPE_F);
         break;
      case nir_tex_src_comparitor:
         shadow_comparitor = retype(src, BRW_REGISTER_TYPE_F);
         break;
      case nir_tex_src_coord:
         switch (instr->op) {
         case nir_texop_txf:
         case nir_texop_txf_ms:
            coordinate = retype(src, BRW_REGISTER_TYPE_D);
            break;
         default:
            coordinate = retype(src, BRW_REGISTER_TYPE_F);
            break;
         }
         break;
      case nir_tex_src_ddx:
         lod = retype(src, BRW_REGISTER_TYPE_F);
         lod_components = nir_tex_instr_src_size(instr, i);
         break;
      case nir_tex_src_ddy:
         lod2 = retype(src, BRW_REGISTER_TYPE_F);
         break;
      case nir_tex_src_lod:
         switch (instr->op) {
         case nir_texop_txs:
            lod = retype(src, BRW_REGISTER_TYPE_UD);
            break;
         case nir_texop_txf:
            lod = retype(src, BRW_REGISTER_TYPE_D);
            break;
         default:
            lod = retype(src, BRW_REGISTER_TYPE_F);
            break;
         }
         break;
      case nir_tex_src_ms_index:
         sample_index = retype(src, BRW_REGISTER_TYPE_UD);
         break;
      case nir_tex_src_offset:
         tex_offset = retype(src, BRW_REGISTER_TYPE_D);
         if (instr->is_array)
            offset_components = instr->coord_components - 1;
         else
            offset_components = instr->coord_components;
         break;
      case nir_tex_src_projector:
         unreachable("should be lowered");

      case nir_tex_src_sampler_offset: {
         /* Figure out the highest possible sampler index and mark it as used */
         uint32_t max_used = sampler + instr->sampler_array_size - 1;
         if (instr->op == nir_texop_tg4 && devinfo->gen < 8) {
            max_used += stage_prog_data->binding_table.gather_texture_start;
         } else {
            max_used += stage_prog_data->binding_table.texture_start;
         }
         brw_mark_surface_used(prog_data, max_used);

         /* Emit code to evaluate the actual indexing expression */
         sampler_reg = vgrf(glsl_type::uint_type);
         bld.ADD(sampler_reg, src, fs_reg(sampler));
         bld.emit_uniformize(sampler_reg, sampler_reg);
         break;
      }

      default:
         unreachable("unknown texture source");
      }
   }

   if (instr->op == nir_texop_txf_ms) {
      if (devinfo->gen >= 7 &&
          key_tex->compressed_multisample_layout_mask & (1 << sampler)) {
         mcs = emit_mcs_fetch(coordinate, instr->coord_components, sampler_reg);
      } else {
         mcs = fs_reg(0u);
      }
   }

   for (unsigned i = 0; i < 3; i++) {
      if (instr->const_offset[i] != 0) {
         assert(offset_components == 0);
         tex_offset = fs_reg(brw_texture_offset(instr->const_offset, 3));
         break;
      }
   }

   enum glsl_base_type dest_base_type;
   switch (instr->dest_type) {
   case nir_type_float:
      dest_base_type = GLSL_TYPE_FLOAT;
      break;
   case nir_type_int:
      dest_base_type = GLSL_TYPE_INT;
      break;
   case nir_type_unsigned:
      dest_base_type = GLSL_TYPE_UINT;
      break;
   default:
      unreachable("bad type");
   }

   const glsl_type *dest_type =
      glsl_type::get_instance(dest_base_type, nir_tex_instr_dest_size(instr),
                              1);

   ir_texture_opcode op;
   switch (instr->op) {
   case nir_texop_lod: op = ir_lod; break;
   case nir_texop_query_levels: op = ir_query_levels; break;
   case nir_texop_tex: op = ir_tex; break;
   case nir_texop_tg4: op = ir_tg4; break;
   case nir_texop_txb: op = ir_txb; break;
   case nir_texop_txd: op = ir_txd; break;
   case nir_texop_txf: op = ir_txf; break;
   case nir_texop_txf_ms: op = ir_txf_ms; break;
   case nir_texop_txl: op = ir_txl; break;
   case nir_texop_txs: op = ir_txs; break;
   default:
      unreachable("unknown texture opcode");
   }

   emit_texture(op, dest_type, coordinate, instr->coord_components,
                shadow_comparitor, lod, lod2, lod_components, sample_index,
                tex_offset, mcs, gather_component,
                is_cube_array, is_rect, sampler, sampler_reg, texunit);

   fs_reg dest = get_nir_dest(instr->dest);
   dest.type = this->result.type;
   unsigned num_components = nir_tex_instr_dest_size(instr);
   emit_percomp(bld, fs_inst(BRW_OPCODE_MOV, dest, this->result),
                (1 << num_components) - 1);
}

void
fs_visitor::nir_emit_jump(const fs_builder &bld, nir_jump_instr *instr)
{
   switch (instr->type) {
   case nir_jump_break:
      bld.emit(BRW_OPCODE_BREAK);
      break;
   case nir_jump_continue:
      bld.emit(BRW_OPCODE_CONTINUE);
      break;
   case nir_jump_return:
   default:
      unreachable("unknown jump");
   }
}