src/compiler/glsl/lower_subroutine.cpp

   1 /*
   2  * Copyright © 2015 Red Hat
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * \file lower_subroutine.cpp
  26  *
  27  * lowers subroutines to an if ladder.
  28  */
  29
  30 #include "compiler/glsl_types.h"
  31 #include "glsl_parser_extras.h"
  32 #include "ir.h"
  33 #include "ir_builder.h"
  34
  35 using namespace ir_builder;
  36 namespace {
  37
  38 class lower_subroutine_visitor : public ir_hierarchical_visitor {
  39 public:
  40    lower_subroutine_visitor(struct _mesa_glsl_parse_state *state)
  41       : state(state)
  42    {
  43       this->progress = false;
  44    }
  45
  46    ir_visitor_status visit_leave(ir_call *);
  47    ir_call *call_clone(ir_call *call, ir_function_signature *callee);
  48    bool progress;
  49    struct _mesa_glsl_parse_state *state;
  50 };
  51
  52 }
  53
  54 bool
  55 lower_subroutine(exec_list *instructions, struct _mesa_glsl_parse_state *state)
  56 {
  57    lower_subroutine_visitor v(state);
  58    visit_list_elements(&v, instructions);
  59    return v.progress;
  60 }
  61
  62 ir_call *
  63 lower_subroutine_visitor::call_clone(ir_call *call, ir_function_signature *callee)
  64 {
  65    void *mem_ctx = ralloc_parent(call);
  66    ir_dereference_variable *new_return_ref = NULL;
  67    if (call->return_deref != NULL)
  68       new_return_ref = call->return_deref->clone(mem_ctx, NULL);
  69
  70    exec_list new_parameters;
  71
  72    foreach_in_list(ir_instruction, ir, &call->actual_parameters) {
  73       new_parameters.push_tail(ir->clone(mem_ctx, NULL));
  74    }
  75
  76    return new(mem_ctx) ir_call(callee, new_return_ref, &new_parameters);
  77 }
  78
  79 ir_visitor_status
  80 lower_subroutine_visitor::visit_leave(ir_call *ir)
  81 {
  82    if (!ir->sub_var)
  83       return visit_continue;
  84
  85    void *mem_ctx = ralloc_parent(ir);
  86    ir_if *last_branch = NULL;
  87
  88    for (int s = this->state->num_subroutines - 1; s >= 0; s--) {
  89       ir_rvalue *var;
  90       ir_constant *lc = new(mem_ctx)ir_constant(s);
  91       ir_function *fn = this->state->subroutines[s];
  92       bool is_compat = false;
  93
  94       for (int i = 0; i < fn->num_subroutine_types; i++) {
  95          if (ir->sub_var->type->without_array() == fn->subroutine_types[i]) {
  96             is_compat = true;
  97             break;
  98          }
  99       }
 100       if (is_compat == false)
 101          continue;
 102
 103       if (ir->array_idx != NULL)
 104          var = ir->array_idx->clone(mem_ctx, NULL);
 105       else
 106          var = new(mem_ctx) ir_dereference_variable(ir->sub_var);
 107
 108       ir_function_signature *sub_sig =
 109          fn->exact_matching_signature(this->state,
 110                                       &ir->actual_parameters);
 111
 112       ir_call *new_call = call_clone(ir, sub_sig);
 113       if (!last_branch)
 114          last_branch = if_tree(equal(subr_to_int(var), lc), new_call);
 115       else
 116          last_branch = if_tree(equal(subr_to_int(var), lc), new_call, last_branch);
 117    }
 118    if (last_branch)
 119       ir->insert_before(last_branch);
 120    ir->remove();
 121
 122    return visit_continue;
 123 }