标签：gcc   源代码   分析   

tree.def 中第0x3d个元素是

DEFTREECODE (CALL_EXPR, "call_expr", "e", 3)

下面是debug_tree()函数的结果，可以看出expand_expr()函数到gen_rtx()函数的调用过程！

expand_expr code = 3d
 <call_expr 840f0
    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>
    volatile
    arg 0 <addr_expr 84090
        type <pointer_type 98f48 type <function_type 956e8>
            permanent unsigned SI size <integer_cst 8254c 4>
            align 32 size_unit 8 sep_unit 32 symtab 0
       
        arg 0 <function_decl 95740 printf type <function_type 956e8>
            external public permanent used QI file /usr/include/stdio.h line 214
            align 1 size_unit 1 offset 0 chain <function_decl 954d8 ungetc>
    arg 1 <tree_list 83270
        value <nop_expr 840d8 type <pointer_type 9117c>
            literal
            arg 0 <nop_expr 840c0 type <pointer_type 88a44>
                literal
                arg 0 <addr_expr 840a8 type <pointer_type 94f58>
                    literal
                    arg 0 <string_cst 84014 type <array_type 94ef4>
                        static literal "Hello, world!
"(nil)

expand_expr code = 71
 <nop_expr 840d8
    type <pointer_type 9117c
        type <integer_type 91130 char readonly permanent QI
            size <integer_cst 82638 literal permanent 1
            align 8 size_unit 8 sep_unit 8 symtab 0
            sep <integer_cst 82608 literal permanent -128 precision 8 min <integer_cst 82608 -128>
            max <integer_cst 82620 literal permanent 127
            pointer_to_this <pointer_type 9117c>
        permanent unsigned SI
        size <integer_cst 8254c literal permanent 4
        align 32 size_unit 8 sep_unit 32 symtab 0
        chain <function_type 912c0>
    literal
    arg 0 <nop_expr 840c0
        type <pointer_type 88a44 type <integer_type 825bc char>
            permanent unsigned SI size <integer_cst 8254c 4>
            align 32 size_unit 8 sep_unit 32 symtab 0
            chain <array_type 88a90>
        literal
        arg 0 <addr_expr 840a8 type <pointer_type 94f58>
            literal
            arg 0 <string_cst 84014 type <array_type 94ef4>
                static literal "Hello, world!
"
expand_expr code = 71
 <nop_expr 840c0
    type <pointer_type 88a44
        type <integer_type 825bc char permanent QI
            size <integer_cst 82638 literal permanent 1
            align 8 size_unit 8 sep_unit 8 symtab 0
            sep <integer_cst 82608 literal permanent -128 precision 8 min <integer_cst 82608 -128>
            max <integer_cst 82620 literal permanent 127
            pointer_to_this <pointer_type 88a44> chain <integer_type 826a8 long int>
        permanent unsigned SI
        size <integer_cst 8254c literal permanent 4
        align 32 size_unit 8 sep_unit 32 symtab 0
        chain <array_type 88a90>
    literal
    arg 0 <addr_expr 840a8
        type <pointer_type 94f58 type <array_type 94ef4>
            unsigned SI size <integer_cst 8254c 4>
            align 32 size_unit 8 sep_unit 32 symtab 0
        literal
        arg 0 <string_cst 84014 type <array_type 94ef4>
            static literal "Hello, world!
"
expand_expr code = 74
 <addr_expr 840a8
    type <pointer_type 94f58
        type <array_type 94ef4 type <integer_type 825bc char>
            BLK
            size <integer_cst 94f40 literal 15
            align 8 size_unit 8 sep_unit 8 symtab 0
            sep <integer_cst 82638 literal permanent 1 domain <integer_type 94ea8>
            pointer_to_this <pointer_type 94f58> chain <pointer_type 94f58>
        unsigned SI
        size <integer_cst 8254c literal permanent 4
        align 32 size_unit 8 sep_unit 32 symtab 0
    literal
    arg 0 <string_cst 84014 type <array_type 94ef4>
        static literal "Hello, world!
"
expand_expr code = 26
 <string_cst 84014
    type <array_type 94ef4
        type <integer_type 825bc char permanent QI
            size <integer_cst 82638 literal permanent 1
            align 8 size_unit 8 sep_unit 8 symtab 0
            sep <integer_cst 82608 literal permanent -128 precision 8 min <integer_cst 82608 -128>
            max <integer_cst 82620 literal permanent 127
            pointer_to_this <pointer_type 88a44> chain <integer_type 826a8 long int>
        BLK
        size <integer_cst 94f40 literal 15
        align 8 size_unit 8 sep_unit 8 symtab 0 sep <integer_cst 82638 1>
        domain <integer_type 94ea8 SI
            size <integer_cst 8254c literal permanent 4
            align 32 size_unit 8 sep_unit 32 symtab 0
            sep <integer_cst 84048 literal 0 precision 32 min <integer_cst 84048 0>
            max <integer_cst 84078 literal 14
        pointer_to_this <pointer_type 94f58> chain <pointer_type 94f58>
    static literal "Hello, world!
"

(symbol_ref:SI ("*LC0"))

(mem:BLK (symbol_ref:SI ("*LC0")))

(pre_dec:SI (reg:SI 7))

(mem:SI (pre_dec:SI (reg:SI 7)))

(set (mem:SI (pre_dec:SI (reg:SI 7)))
   (symbol_ref:SI ("*LC0")))

(insn_list 6 (nil))

(insn_list 2 (insn_list 6 (nil)))

(sequence[ ] )

(reg:SI 0)

(const_int 4)
emit_call_1 funexp symbol_ref

(mem:QI (symbol_ref/v:SI ("printf")))

(call (mem:QI (symbol_ref/v:SI ("printf")))
   (const_int 4))

(set (reg:SI 0)
   (call (mem:QI (symbol_ref/v:SI ("printf")))
       (const_int 4)))
emit_call_insn

gcc源代码分析，debug_tree()函数的利用

标签：gcc   源代码   分析   

原文地址：http://blog.csdn.net/oldlinux/article/details/42403479