text: /*
   * Copyright © 2015 Red Hat
   *
   * 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 "nir.h"
  #include "nir_control_flow.h"
  
  /* Secret Decoder Ring:
   *   clone_foo():
   *        Allocate and clone a foo.
   *   __clone_foo():
   *        Clone body of foo (ie. parent class, embedded struct, etc)
   */
  
  typedef struct {
     /* True if we are cloning an entire shader. */
     bool global_clone;
  
     /* If true allows the clone operation to fall back to the original pointer
      * if no clone pointer is found in the remap table.  This allows us to
      * clone a loop body without having to add srcs from outside the loop to
      * the remap table. This is useful for loop unrolling.
      */
     bool allow_remap_fallback;
  
     /* maps orig ptr -> cloned ptr: */
     struct hash_table *remap_table;
  
     /* List of phi sources. */
     struct list_head phi_srcs;
  
     /* new shader object, used as memctx for just about everything else: */
     nir_shader *ns;
  } clone_state;
  
  static void
  init_clone_state(clone_state *state, struct hash_table *remap_table,
                   bool global, bool allow_remap_fallback)
  {
     state->global_clone = global;
     state->allow_remap_fallback = allow_remap_fallback;
  
     if (remap_table) {
        state->remap_table = remap_table;
     } else {
        state->remap_table = _mesa_pointer_hash_table_create(NULL);
     }
  
     list_inithead(&state->phi_srcs);
  }
  
  static void
  free_clone_state(clone_state *state)
  {
     _mesa_hash_table_destroy(state->remap_table, NULL);
  }
  
  static inline void *
  _lookup_ptr(clone_state *state, const void *ptr, bool global)
  {
     struct hash_entry *entry;
  
     if (!ptr)
        return NULL;
  
     if (!state->global_clone && global)
        return (void *)ptr;
  
     entry = _mesa_hash_table_search(state->remap_table, ptr);
     if (!entry) {
        assert(state->allow_remap_fallback);
        return (void *)ptr;
     }
  
     return entry->data;
  }
  
  static void
  add_remap(clone_state *state, void *nptr, const void *ptr)
  {
     _mesa_hash_table_insert(state->remap_table, ptr, nptr);
  }
  
  static void *
  remap_local(clone_state *state, const void *ptr)
  {
     return _lookup_ptr(state, ptr, false);
  }
  
  static void *
  remap_global(clone_state *state, const void *ptr)
  {
     return _lookup_ptr(state, ptr, true);
  }
  
  static nir_register *
  remap_reg(clone_state *state, const nir_register *reg)
  {
     return _lookup_ptr(state, reg, false);
  }
  
  static nir_variable *
  remap_var(clone_state *state, const nir_variable *var)
  {
     return _lookup_ptr(state, var, nir_variable_is_global(var));
  }
  
  nir_constant *
  nir_constant_clone(const nir_constant *c, nir_variable *nvar)
  {
     nir_constant *nc = ralloc(nvar, nir_constant);
  
     memcpy(nc->values, c->values, sizeof(nc->values));
     nc->num_elements = c->num_elements;
     nc->elements = ralloc_array(nvar, nir_constant *, c->num_elements);
     for (unsigned i = 0; i < c->num_elements; i++) {
        nc->elements[i] = nir_constant_clone(c->elements[i], nvar);
     }
  
     return nc;
  }
  
  /* NOTE: for cloning nir_variables, bypass nir_variable_create to avoid
   * having to deal with locals and globals separately:
   */
  nir_variable *
  nir_variable_clone(const nir_variable *var, nir_shader *shader)
  {
     nir_variable *nvar = rzalloc(shader, nir_variable);
  
     nvar->type = var->type;
     nvar->name = ralloc_strdup(nvar, var->name);
     nvar->data = var->data;
     nvar->num_state_slots = var->num_state_slots;
     if (var->num_state_slots) {
        nvar->state_slots = ralloc_array(nvar, nir_state_slot, var->num_state_slots);
        memcpy(nvar->state_slots, var->state_slots,
               var->num_state_slots * sizeof(nir_state_slot));
     }
     if (var->constant_initializer) {
        nvar->constant_initializer =
           nir_constant_clone(var->constant_initializer, nvar);
     }
     nvar->interface_type = var->interface_type;
  
     nvar->num_members = var->num_members;
     if (var->num_members) {
        nvar->members = ralloc_array(nvar, struct nir_variable_data,
                                     var->num_members);
        memcpy(nvar->members, var->members,
               var->num_members * sizeof(*var->members));
     }
  
     return nvar;
  }
  
  static nir_variable *
  clone_variable(clone_state *state, const nir_variable *var)
  {
     nir_variable *nvar = nir_variable_clone(var, state->ns);
     add_remap(state, nvar, var);
  
     return nvar;
  }
  
  /* clone list of nir_variable: */
  static void
  clone_var_list(clone_state *state, struct exec_list *dst,
                 const struct exec_list *list)
  {
     exec_list_make_empty(dst);
     foreach_list_typed(nir_variable, var, node, list) {
        nir_variable *nvar = clone_variable(state, var);
        exec_list_push_tail(dst, &nvar->node);
     }
  }
  
  /* NOTE: for cloning nir_registers, bypass nir_global/local_reg_create()
   * to avoid having to deal with locals and globals separately:
   */
  static nir_register *
  clone_register(clone_state *state, const nir_register *reg)
  {
     nir_register *nreg = rzalloc(state->ns, nir_register);
     add_remap(state, nreg, reg);
  
     nreg->num_components = reg->num_components;
     nreg->bit_size = reg->bit_size;
     nreg->num_array_elems = reg->num_array_elems;
     nreg->index = reg->index;
     nreg->name = ralloc_strdup(nreg, reg->name);
  
     /* reconstructing uses/defs/if_uses handled by nir_instr_insert() */
     list_inithead(&nreg->uses);
     list_inithead(&nreg->defs);
     list_inithead(&nreg->if_uses);
  
     return nreg;
  }
  
  /* clone list of nir_register: */
  static void
  clone_reg_list(clone_state *state, struct exec_list *dst,
                 const struct exec_list *list)
  {
     exec_list_make_empty(dst);
     foreach_list_typed(nir_register, reg, node, list) {
        nir_register *nreg = clone_register(state, reg);
        exec_list_push_tail(dst, &nreg->node);
     }
  }
  
  static void
  __clone_src(clone_state *state, void *ninstr_or_if,
              nir_src *nsrc, const nir_src *src)
  {
     nsrc->is_ssa = src->is_ssa;
     if (src->is_ssa) {
        nsrc->ssa = remap_local(state, src->ssa);
     } else {
        nsrc->reg.reg = remap_reg(state, src->reg.reg);
        if (src->reg.indirect) {
           nsrc->reg.indirect = ralloc(ninstr_or_if, nir_src);
           __clone_src(state, ninstr_or_if, nsrc->reg.indirect, src->reg.indirect);
        }
        nsrc->reg.base_offset = src->reg.base_offset;
     }
  }
  
  static void
  __clone_dst(clone_state *state, nir_instr *ninstr,
              nir_dest *ndst, const nir_dest *dst)
  {
     ndst->is_ssa = dst->is_ssa;
     if (dst->is_ssa) {
        nir_ssa_dest_init(ninstr, ndst, dst->ssa.num_components,
                          dst->ssa.bit_size, dst->ssa.name);
        add_remap(state, &ndst->ssa, &dst->ssa);
     } else {
        ndst->reg.reg = remap_reg(state, dst->reg.reg);
        if (dst->reg.indirect) {
           ndst->reg.indirect = ralloc(ninstr, nir_src);
           __clone_src(state, ninstr, ndst->reg.indirect, dst->reg.indirect);
        }
        ndst->reg.base_offset = dst->reg.base_offset;
     }
  }
  
  nir_alu_instr *
  nir_alu_instr_clone(nir_shader *shader, const nir_alu_instr *orig)
  {
     nir_alu_instr *clone = nir_alu_instr_create(shader, orig->op);
  
     clone->exact = orig->exact;
  
     for (unsigned i = 0; i < nir_op_infos[orig->op].num_inputs; i++)
        nir_alu_src_copy(&clone->src[i], &orig->src[i], clone);
  
     nir_ssa_dest_init(&clone->instr,
                       &clone->dest.dest,
                       orig->dest.dest.ssa.num_components,
                       orig->dest.dest.ssa.bit_size,
                       orig->dest.dest.ssa.name);
     clone->dest.write_mask = orig->dest.write_mask;
  
     return clone;
  }
  
  static nir_alu_instr *
  clone_alu(clone_state *state, const nir_alu_instr *alu)
  {
     nir_alu_instr *nalu = nir_alu_instr_create(state->ns, alu->op);
     nalu->exact = alu->exact;
     nalu->no_signed_wrap = alu->no_signed_wrap;
     nalu->no_unsigned_wrap = alu->no_unsigned_wrap;
  
     __clone_dst(state, &nalu->instr, &nalu->dest.dest, &alu->dest.dest);
     nalu->dest.saturate = alu->dest.saturate;
     nalu->dest.write_mask = alu->dest.write_mask;
  
     for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) {
        __clone_src(state, &nalu->instr, &nalu->src[i].src, &alu->src[i].src);
        nalu->src[i].negate = alu->src[i].negate;
        nalu->src[i].abs = alu->src[i].abs;
        memcpy(nalu->src[i].swizzle, alu->src[i].swizzle,
               sizeof(nalu->src[i].swizzle));
     }
  
     return nalu;
  }
  
  static nir_deref_instr *
  clone_deref_instr(clone_state *state, const nir_deref_instr *deref)
  {
     nir_deref_instr *nderef =
        nir_deref_instr_create(state->ns, deref->deref_type);
  
     __clone_dst(state, &nderef->instr, &nderef->dest, &deref->dest);
  
     nderef->mode = deref->mode;
     nderef->type = deref->type;
  
     if (deref->deref_type == nir_deref_type_var) {
        nderef->var = remap_var(state, deref->var);
        return nderef;
     }
  
     __clone_src(state, &nderef->instr, &nderef->parent, &deref->parent);
  
     switch (deref->deref_type) {
     case nir_deref_type_struct:
        nderef->strct.index = deref->strct.index;
        break;
  
     case nir_deref_type_array:
     case nir_deref_type_ptr_as_array:
        __clone_src(state, &nderef->instr,
                    &nderef->arr.index, &deref->arr.index);
        break;
  
     case nir_deref_type_array_wildcard:
        /* Nothing to do */
        break;
  
     case nir_deref_type_cast:
        nderef->cast.ptr_stride = deref->cast.ptr_stride;
        break;
  
     default:
        unreachable("Invalid instruction deref type");
     }
  
     return nderef;
  }
  
  static nir_intrinsic_instr *
  clone_intrinsic(clone_state *state, const nir_intrinsic_instr *itr)
  {
     nir_intrinsic_instr *nitr =
        nir_intrinsic_instr_create(state->ns, itr->intrinsic);
  
     unsigned num_srcs = nir_intrinsic_infos[itr->intrinsic].num_srcs;
  
     if (nir_intrinsic_infos[itr->intrinsic].has_dest)
        __clone_dst(state, &nitr->instr, &nitr->dest, &itr->dest);
  
     nitr->num_components = itr->num_components;
     memcpy(nitr->const_index, itr->const_index, sizeof(nitr->const_index));
  
     for (unsigned i = 0; i < num_srcs; i++)
        __clone_src(state, &nitr->instr, &nitr->src[i], &itr->src[i]);
  
     return nitr;
  }
  
  static nir_load_const_instr *
  clone_load_const(clone_state *state, const nir_load_const_instr *lc)
  {
     nir_load_const_instr *nlc =
        nir_load_const_instr_create(state->ns, lc->def.num_components,
                                    lc->def.bit_size);
  
     memcpy(&nlc->value, &lc->value, sizeof(*nlc->value) * lc->def.num_components);
  
     add_remap(state, &nlc->def, &lc->def);
  
     return nlc;
  }
  
  static nir_ssa_undef_instr *
  clone_ssa_undef(clone_state *state, const nir_ssa_undef_instr *sa)
  {
     nir_ssa_undef_instr *nsa =
        nir_ssa_undef_instr_create(state->ns, sa->def.num_components,
                                   sa->def.bit_size);
  
     add_remap(state, &nsa->def, &sa->def);
  
     return nsa;
  }
  
  static nir_tex_instr *
  clone_tex(clone_state *state, const nir_tex_instr *tex)
  {
     nir_tex_instr *ntex = nir_tex_instr_create(state->ns, tex->num_srcs);
  
     ntex->sampler_dim = tex->sampler_dim;
     ntex->dest_type = tex->dest_type;
     ntex->op = tex->op;
     __clone_dst(state, &ntex->instr, &ntex->dest, &tex->dest);
     for (unsigned i = 0; i < ntex->num_srcs; i++) {
        ntex->src[i].src_type = tex->src[i].src_type;
        __clone_src(state, &ntex->instr, &ntex->src[i].src, &tex->src[i].src);
     }
     ntex->coord_components = tex->coord_components;
     ntex->is_array = tex->is_array;
     ntex->is_shadow = tex->is_shadow;
     ntex->is_new_style_shadow = tex->is_new_style_shadow;
     ntex->component = tex->component;
     memcpy(ntex->tg4_offsets, tex->tg4_offsets, sizeof(tex->tg4_offsets));
  
     ntex->texture_index = tex->texture_index;
     ntex->texture_array_size = tex->texture_array_size;
     ntex->sampler_index = tex->sampler_index;
  
     ntex->texture_non_uniform = tex->texture_non_uniform;
     ntex->sampler_non_uniform = tex->sampler_non_uniform;
  
     return ntex;
  }
  
  static nir_phi_instr *
  clone_phi(clone_state *state, const nir_phi_instr *phi, nir_block *nblk)
  {
     nir_phi_instr *nphi = nir_phi_instr_create(state->ns);
  
     __clone_dst(state, &nphi->instr, &nphi->dest, &phi->dest);
  
     /* Cloning a phi node is a bit different from other instructions.  The
      * sources of phi instructions are the only time where we can use an SSA
      * def before it is defined.  In order to handle this, we just copy over
      * the sources from the old phi instruction directly and then fix them up
      * in a second pass once all the instrutions in the function have been
      * properly cloned.
      *
      * In order to ensure that the copied sources (which are the same as the
      * old phi instruction's sources for now) don't get inserted into the old
      * shader's use-def lists, we have to add the phi instruction *before* we
      * set up its sources.
      */
     nir_instr_insert_after_block(nblk, &nphi->instr);
  
     foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
        nir_phi_src *nsrc = ralloc(nphi, nir_phi_src);
  
        /* Just copy the old source for now. */
        memcpy(nsrc, src, sizeof(*src));
  
        /* Since we're not letting nir_insert_instr handle use/def stuff for us,
         * we have to set the parent_instr manually.  It doesn't really matter
         * when we do it, so we might as well do it here.
         */
        nsrc->src.parent_instr = &nphi->instr;
  
        /* Stash it in the list of phi sources.  We'll walk this list and fix up
         * sources at the very end of clone_function_impl.
         */
        list_add(&nsrc->src.use_link, &state->phi_srcs);
  
        exec_list_push_tail(&nphi->srcs, &nsrc->node);
     }
  
     return nphi;
  }
  
  static nir_jump_instr *
  clone_jump(clone_state *state, const nir_jump_instr *jmp)
  {
     nir_jump_instr *njmp = nir_jump_instr_create(state->ns, jmp->type);
  
     return njmp;
  }
  
  static nir_call_instr *
  clone_call(clone_state *state, const nir_call_instr *call)
  {
     nir_function *ncallee = remap_global(state, call->callee);
     nir_call_instr *ncall = nir_call_instr_create(state->ns, ncallee);
  
     for (unsigned i = 0; i < ncall->num_params; i++)
        __clone_src(state, ncall, &ncall->params[i], &call->params[i]);
  
     return ncall;
  }
  
  static nir_instr *
  clone_instr(clone_state *state, const nir_instr *instr)
  {
     switch (instr->type) {
     case nir_instr_type_alu:
        return &clone_alu(state, nir_instr_as_alu(instr))->instr;
     case nir_instr_type_deref:
        return &clone_deref_instr(state, nir_instr_as_deref(instr))->instr;
     case nir_instr_type_intrinsic:
        return &clone_intrinsic(state, nir_instr_as_intrinsic(instr))->instr;
     case nir_instr_type_load_const:
        return &clone_load_const(state, nir_instr_as_load_const(instr))->instr;
     case nir_instr_type_ssa_undef:
        return &clone_ssa_undef(state, nir_instr_as_ssa_undef(instr))->instr;
     case nir_instr_type_tex:
        return &clone_tex(state, nir_instr_as_tex(instr))->instr;
     case nir_instr_type_phi:
        unreachable("Cannot clone phis with clone_instr");
     case nir_instr_type_jump:
        return &clone_jump(state, nir_instr_as_jump(instr))->instr;
     case nir_instr_type_call:
        return &clone_call(state, nir_instr_as_call(instr))->instr;
     case nir_instr_type_parallel_copy:
        unreachable("Cannot clone parallel copies");
     default:
        unreachable("bad instr type");
        return NULL;
     }
  }
  
  static nir_block *
  clone_block(clone_state *state, struct exec_list *cf_list, const nir_block *blk)
  {
     /* Don't actually create a new block.  Just use the one from the tail of
      * the list.  NIR guarantees that the tail of the list is a block and that
      * no two blocks are side-by-side in the IR;  It should be empty.
      */
     nir_block *nblk =
        exec_node_data(nir_block, exec_list_get_tail(cf_list), cf_node.node);
     assert(nblk->cf_node.type == nir_cf_node_block);
     assert(exec_list_is_empty(&nblk->instr_list));
  
     /* We need this for phi sources */
     add_remap(state, nblk, blk);
  
     nir_foreach_instr(instr, blk) {
        if (instr->type == nir_instr_type_phi) {
           /* Phi instructions are a bit of a special case when cloning because
            * we don't want inserting the instruction to automatically handle
            * use/defs for us.  Instead, we need to wait until all the
            * blocks/instructions are in so that we can set their sources up.
            */
           clone_phi(state, nir_instr_as_phi(instr), nblk);
        } else {
           nir_instr *ninstr = clone_instr(state, instr);
           nir_instr_insert_after_block(nblk, ninstr);
        }
     }
  
     return nblk;
  }
  
  static void
  clone_cf_list(clone_state *state, struct exec_list *dst,
                const struct exec_list *list);
  
  static nir_if *
  clone_if(clone_state *state, struct exec_list *cf_list, const nir_if *i)
  {
     nir_if *ni = nir_if_create(state->ns);
     ni->control = i->control;
  
     __clone_src(state, ni, &ni->condition, &i->condition);
  
     nir_cf_node_insert_end(cf_list, &ni->cf_node);
  
     clone_cf_list(state, &ni->then_list, &i->then_list);
     clone_cf_list(state, &ni->else_list, &i->else_list);
  
     return ni;
  }
  
  static nir_loop *
  clone_loop(clone_state *state, struct exec_list *cf_list, const nir_loop *loop)
  {
     nir_loop *nloop = nir_loop_create(state->ns);
     nloop->control = loop->control;
     nloop->partially_unrolled = loop->partially_unrolled;
  
     nir_cf_node_insert_end(cf_list, &nloop->cf_node);
  
     clone_cf_list(state, &nloop->body, &loop->body);
  
     return nloop;
  }
  
  /* clone list of nir_cf_node: */
  static void
  clone_cf_list(clone_state *state, struct exec_list *dst,
                const struct exec_list *list)
  {
     foreach_list_typed(nir_cf_node, cf, node, list) {
        switch (cf->type) {
        case nir_cf_node_block:
           clone_block(state, dst, nir_cf_node_as_block(cf));
           break;
        case nir_cf_node_if:
           clone_if(state, dst, nir_cf_node_as_if(cf));
           break;
        case nir_cf_node_loop:
           clone_loop(state, dst, nir_cf_node_as_loop(cf));
           break;
        default:
           unreachable("bad cf type");
        }
     }
  }
  
  /* After we've cloned almost everything, we have to walk the list of phi
   * sources and fix them up.  Thanks to loops, the block and SSA value for a
   * phi source may not be defined when we first encounter it.  Instead, we
   * add it to the phi_srcs list and we fix it up here.
   */
  static void
  fixup_phi_srcs(clone_state *state)
  {
     list_for_each_entry_safe(nir_phi_src, src, &state->phi_srcs, src.use_link) {
        src->pred = remap_local(state, src->pred);
  
        /* Remove from this list */
        list_del(&src->src.use_link);
  
        if (src->src.is_ssa) {
           src->src.ssa = remap_local(state, src->src.ssa);
           list_addtail(&src->src.use_link, &src->src.ssa->uses);
        } else {
           src->src.reg.reg = remap_reg(state, src->src.reg.reg);
           list_addtail(&src->src.use_link, &src->src.reg.reg->uses);
        }
     }
     assert(list_is_empty(&state->phi_srcs));
  }
  
  void
  nir_cf_list_clone(nir_cf_list *dst, nir_cf_list *src, nir_cf_node *parent,
                    struct hash_table *remap_table)
  {
     exec_list_make_empty(&dst->list);
     dst->impl = src->impl;
  
     if (exec_list_is_empty(&src->list))
        return;
  
     clone_state state;
     init_clone_state(&state, remap_table, false, true);
  
     /* We use the same shader */
     state.ns = src->impl->function->shader;
  
     /* The control-flow code assumes that the list of cf_nodes always starts
      * and ends with a block.  We start by adding an empty block.
      */
     nir_block *nblk = nir_block_create(state.ns);
     nblk->cf_node.parent = parent;
     exec_list_push_tail(&dst->list, &nblk->cf_node.node);
  
     clone_cf_list(&state, &dst->list, &src->list);
  
     fixup_phi_srcs(&state);
  }
  
  static nir_function_impl *
  clone_function_impl(clone_state *state, const nir_function_impl *fi)
  {
     nir_function_impl *nfi = nir_function_impl_create_bare(state->ns);
  
     clone_var_list(state, &nfi->locals, &fi->locals);
     clone_reg_list(state, &nfi->registers, &fi->registers);
     nfi->reg_alloc = fi->reg_alloc;
  
     assert(list_is_empty(&state->phi_srcs));
  
     clone_cf_list(state, &nfi->body, &fi->body);
  
     fixup_phi_srcs(state);
  
     /* All metadata is invalidated in the cloning process */
     nfi->valid_metadata = 0;
  
     return nfi;
  }
  
  nir_function_impl *
  nir_function_impl_clone(nir_shader *shader, const nir_function_impl *fi)
  {
     clone_state state;
     init_clone_state(&state, NULL, false, false);
  
     state.ns = shader;
  
     nir_function_impl *nfi = clone_function_impl(&state, fi);
  
     free_clone_state(&state);
  
     return nfi;
  }
  
  static nir_function *
  clone_function(clone_state *state, const nir_function *fxn, nir_shader *ns)
  {
     assert(ns == state->ns);
     nir_function *nfxn = nir_function_create(ns, fxn->name);
  
     /* Needed for call instructions */
     add_remap(state, nfxn, fxn);
  
     nfxn->num_params = fxn->num_params;
     if (fxn->num_params) {
             nfxn->params = ralloc_array(state->ns, nir_parameter, fxn->num_params);
             memcpy(nfxn->params, fxn->params, sizeof(nir_parameter) * fxn->num_params);
     }
     nfxn->is_entrypoint = fxn->is_entrypoint;
  
     /* At first glance, it looks like we should clone the function_impl here.
      * However, call instructions need to be able to reference at least the
      * function and those will get processed as we clone the function_impls.
      * We stop here and do function_impls as a second pass.
      */
  
     return nfxn;
  }
  
  nir_shader *
  nir_shader_clone(void *mem_ctx, const nir_shader *s)
  {
     clone_state state;
     init_clone_state(&state, NULL, true, false);
  
     nir_shader *ns = nir_shader_create(mem_ctx, s->info.stage, s->options, NULL);
     state.ns = ns;
  
     clone_var_list(&state, &ns->uniforms, &s->uniforms);
     clone_var_list(&state, &ns->inputs,   &s->inputs);
     clone_var_list(&state, &ns->outputs,  &s->outputs);
     clone_var_list(&state, &ns->shared,   &s->shared);
     clone_var_list(&state, &ns->globals,  &s->globals);
     clone_var_list(&state, &ns->system_values, &s->system_values);
  
     /* Go through and clone functions */
     foreach_list_typed(nir_function, fxn, node, &s->functions)
        clone_function(&state, fxn, ns);
  
     /* Only after all functions are cloned can we clone the actual function
      * implementations.  This is because nir_call_instrs need to reference the
      * functions of other functions and we don't know what order the functions
      * will have in the list.
      */
     nir_foreach_function(fxn, s) {
        nir_function *nfxn = remap_global(&state, fxn);
        nfxn->impl = clone_function_impl(&state, fxn->impl);
        nfxn->impl->function = nfxn;
     }
  
     ns->info = s->info;
     ns->info.name = ralloc_strdup(ns, ns->info.name);
     if (ns->info.label)
        ns->info.label = ralloc_strdup(ns, ns->info.label);
  
     ns->num_inputs = s->num_inputs;
     ns->num_uniforms = s->num_uniforms;
     ns->num_outputs = s->num_outputs;
     ns->num_shared = s->num_shared;
     ns->scratch_size = s->scratch_size;
  
     ns->constant_data_size = s->constant_data_size;
     if (s->constant_data_size > 0) {
        ns->constant_data = ralloc_size(ns, s->constant_data_size);
        memcpy(ns->constant_data, s->constant_data, s->constant_data_size);
     }
  
     free_clone_state(&state);
  
     return ns;
  }
  
  /** Overwrites dst and replaces its contents with src
   *
   * Everything ralloc parented to dst and src itself (but not its children)
   * will be freed.
   *
   * This should only be used by test code which needs to swap out shaders with
   * a cloned or deserialized version.
   */
  void
  nir_shader_replace(nir_shader *dst, nir_shader *src)
  {
     /* Delete all of dest's ralloc children */
     void *dead_ctx = ralloc_context(NULL);
     ralloc_adopt(dead_ctx, dst);
     ralloc_free(dead_ctx);
  
     /* Re-parent all of src's ralloc children to dst */
     ralloc_adopt(dst, src);
  
     memcpy(dst, src, sizeof(*dst));
  
     /* We have to move all the linked lists over separately because we need the
      * pointers in the list elements to point to the lists in dst and not src.
      */
     exec_list_move_nodes_to(&src->uniforms,      &dst->uniforms);
     exec_list_move_nodes_to(&src->inputs,        &dst->inputs);
     exec_list_move_nodes_to(&src->outputs,       &dst->outputs);
     exec_list_move_nodes_to(&src->shared,        &dst->shared);
     exec_list_move_nodes_to(&src->globals,       &dst->globals);
     exec_list_move_nodes_to(&src->system_values, &dst->system_values);
  
     /* Now move the functions over.  This takes a tiny bit more work */
     exec_list_move_nodes_to(&src->functions, &dst->functions);
     nir_foreach_function(function, dst)
        function->shader = dst;
  
     ralloc_free(src);
  }
  