workbench/libs/mesa/src/glsl/ir_function_can_inline.cpp

   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->get_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 }