gcc源代码分析，build_pointer_type ()函数分析

标签：gcc   源代码   分析   

      function = build (ADDR_EXPR, build_pointer_type (TREE_TYPE (function)),
            function);

继续分析上篇文章的这句。

/* Constructors for pointer, array and function types.
   (RECORD_TYPE, UNION_TYPE and ENUMERAL_TYPE nodes are
   constructed by language-dependent code, not here.)  */

/* Construct, lay out and return the type of pointers to TO_TYPE.
   If such a type has already been constructed, reuse it.  */

tree
build_pointer_type (to_type)
     tree to_type;
{
  register tree t = TYPE_POINTER_TO (to_type);

/* 下面是debug_tree(to_type);的结果

 <function_type 956e8
    type <integer_type 824d0 int permanent SI
        size <integer_cst 8254c literal permanent 4
        align 32 size_unit 8 sep_unit 32 symtab 0
        sep <integer_cst 8251c literal permanent -2147483648 precision 32 min <integer_cst 8251c -2147483648>
        max <integer_cst 82534 literal permanent 2147483647
        pointer_to_this <pointer_type 88b4c> chain <integer_type 825bc* char>
    permanent EP
    size <integer_cst 82dd8 type <integer_type 82848* unsigned int> literal permanent 8
    align 32 size_unit 8 sep_unit 0 symtab 0
    arg-types <tree_list 95698 permanent
        value <pointer_type 9117c type <integer_type 91130* char>
            permanent unsigned SI size <integer_cst 8254c 4>
            align 32 size_unit 8 sep_unit 32 symtab 0
            chain <function_type 912c0>
    chain <function_type 959b0>
*/

  register struct obstack *ambient_obstack = current_obstack;
  register struct obstack *ambient_saveable_obstack = saveable_obstack;

  /* First, if we already have a type for pointers to TO_TYPE, use it.  */

  if (t)
    return t;

  /* We need a new one.  If TO_TYPE is permanent, make this permanent too.  */
  if (TREE_PERMANENT (to_type))
    {
      current_obstack = &permanent_obstack;
      saveable_obstack = &permanent_obstack;
    }

  t = make_node (POINTER_TYPE);

/*下面是debug_tree(t);的结果

 <pointer_type 98f48 permanent VOID
    align 1 size_unit 1 sep_unit 0 symtab 0
*/

  TREE_TYPE (t) = to_type;

/*下面是debug_tree(t);的结果

/*

 <function_type 956e8
    type <integer_type 824d0 int permanent SI
        size <integer_cst 8254c literal permanent 4
        align 32 size_unit 8 sep_unit 32 symtab 0
        sep <integer_cst 8251c literal permanent -2147483648 precision 32 min <integer_cst 8251c -2147483648>
        max <integer_cst 82534 literal permanent 2147483647
        pointer_to_this <pointer_type 88b4c> chain <integer_type 825bc* char>
    permanent EP
    size <integer_cst 82dd8 type <integer_type 82848* unsigned int> literal permanent 8
    align 32 size_unit 8 sep_unit 0 symtab 0
    arg-types <tree_list 95698 permanent
        value <pointer_type 9117c type <integer_type 91130* char>
            permanent unsigned SI size <integer_cst 8254c 4>
            align 32 size_unit 8 sep_unit 32 symtab 0
            chain <function_type 912c0>
    pointer_to_this <pointer_type 98f48> chain <function_type 959b0>

*/

 <pointer_type 98f48
    type <function_type 956e8
        type <integer_type 824d0 int permanent SI
            size <integer_cst 8254c literal permanent 4
            align 32 size_unit 8 sep_unit 32 symtab 0
            sep <integer_cst 8251c literal permanent -2147483648 precision 32 min <integer_cst 8251c -2147483648>
            max <integer_cst 82534 literal permanent 2147483647
            pointer_to_this <pointer_type 88b4c> chain <integer_type 825bc* char>
        permanent EP
        size <integer_cst 82dd8 literal permanent 8
        align 32 size_unit 8 sep_unit 0 symtab 0
        arg-types <tree_list 95698 permanent value <pointer_type 9117c>
        pointer_to_this <pointer_type 98f48> chain <function_type 959b0>
    permanent unsigned SI size <integer_cst 8254c 4>
    align 32 size_unit 8 sep_unit 32 symtab 0

gcc源代码分析，build_pointer_type ()函数分析

标签：gcc   源代码   分析   

原文地址：http://blog.csdn.net/oldlinux/article/details/42607771