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  1. /*
  2.  * Copyright © 2010 Intel Corporation
  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 ir_function_can_inline.cpp
  26.  *
  27.  * Determines if we can inline a function call using ir_function_inlining.cpp.
  28.  *
  29.  * The primary restriction is that we can't return from the function
  30.  * other than as the last instruction.  We could potentially work
  31.  * around this for some constructs by flattening control flow and
  32.  * moving the return to the end, or by using breaks from a do {} while
  33.  * (0) loop surrounding the function body.
  34.  */
  35.  
  36. #include "ir.h"
  37.  
  38. class ir_function_can_inline_visitor : public ir_hierarchical_visitor {
  39. public:
  40.    ir_function_can_inline_visitor()
  41.    {
  42.       this->num_returns = 0;
  43.    }
  44.  
  45.    virtual ir_visitor_status visit_enter(ir_return *);
  46.  
  47.    int num_returns;
  48. };
  49.  
  50. ir_visitor_status
  51. ir_function_can_inline_visitor::visit_enter(ir_return *ir)
  52. {
  53.    (void) ir;
  54.    this->num_returns++;
  55.    return visit_continue;
  56. }
  57.  
  58. bool
  59. can_inline(ir_call *call)
  60. {
  61.    ir_function_can_inline_visitor v;
  62.    const ir_function_signature *callee = call->callee;
  63.    if (!callee->is_defined)
  64.       return false;
  65.  
  66.    v.run((exec_list *) &callee->body);
  67.  
  68.    /* If the function is empty (no last instruction) or does not end with a
  69.     * return statement, we need to count the implicit return.
  70.     */
  71.    ir_instruction *last = (ir_instruction *)callee->body.get_tail();
  72.    if (last == NULL || !last->as_return())
  73.       v.num_returns++;
  74.  
  75.    return v.num_returns == 1;
  76. }
  77.