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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