? ? ? ? ?在linux下開發難免會用到gcc編譯。GCC（GNU Compiler Collection。GNU編譯器套裝），是由 GNU 開發的編程語言編譯器。它是GNU編譯器套裝以GPL許可證所發行的自由軟件，也是 GNU計劃的關鍵部分。

使用GCC編譯程序時,編譯過程能夠被細分為四個階段:
◆ 預處理(Pre-Processing)
◆ 編譯(Compiling)
◆ 匯編(Assembling)
◆ 鏈接(Linking)

1、預處理 對源碼文件里的文件包括(include)、預編譯語句(如宏定義define等)進行分析，編譯選項為gcc -E *.c

#define DEBUG "debug"int main() {char *a = DEBUG;return 1; }經過上面的預處理后，能夠看到DEBUG被替換成了提前定義的內容

# 1 "hello.c" # 1 "<built-in>" # 1 "<command-line>" # 1 "hello.c"int main() {char *a = "debug";return 1; }2、編譯?調用cc1進行編譯，使用gcc -S選項就能夠生成匯編代碼，這個階段依據輸入文件生成以.o為后綴的目標文件。生成的匯編代碼例如以下：

.file "hello.c".section .rodata .LC0:.string "debug".text .globl main.type main, @function main: .LFB0:.cfi_startprocpushq %rbp.cfi_def_cfa_offset 16.cfi_offset 6, -16movq %rsp, %rbp.cfi_def_cfa_register 6movq $.LC0, -8(%rbp)movl $1, %eaxleave.cfi_def_cfa 7, 8ret.cfi_endproc .LFE0:.size main, .-main.ident "GCC: (GNU) 4.4.6 20110731 (Red Hat 4.4.6-3)".section .note.GNU-stack,"",@progbits3、匯編 ?匯編過程是針對匯編語言的步驟，調用as進行工作。一般來講，.S為后綴的匯編語言源碼文件和匯編、.s為后綴的匯編語言文件經過預編譯和匯編之后都生成以.o為后綴的目標文件。此過程生成ELF格式的目標代碼，使用gcc -c進行匯編

使用readelf -a hello.o能夠看到具體的elf信息

ELF Header:Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 Class: ELF64Data: 2's complement, little endianVersion: 1 (current)OS/ABI: UNIX - System VABI Version: 0Type: REL (Relocatable file)Machine: Advanced Micro Devices X86-64Version: 0x1Entry point address: 0x0Start of program headers: 0 (bytes into file)Start of section headers: 296 (bytes into file)Flags: 0x0Size of this header: 64 (bytes)Size of program headers: 0 (bytes)Number of program headers: 0Size of section headers: 64 (bytes)Number of section headers: 13Section header string table index: 10Section Headers:[Nr] Name Type Address OffsetSize EntSize Flags Link Info Align[ 0] NULL 0000000000000000 000000000000000000000000 0000000000000000 0 0 0[ 1] .text PROGBITS 0000000000000000 000000400000000000000013 0000000000000000 AX 0 0 4[ 2] .rela.text RELA 0000000000000000 000005680000000000000018 0000000000000018 11 1 8[ 3] .data PROGBITS 0000000000000000 000000540000000000000000 0000000000000000 WA 0 0 4[ 4] .bss NOBITS 0000000000000000 000000540000000000000000 0000000000000000 WA 0 0 4[ 5] .rodata PROGBITS 0000000000000000 000000540000000000000006 0000000000000000 A 0 0 1[ 6] .comment PROGBITS 0000000000000000 0000005a000000000000002d 0000000000000001 MS 0 0 1[ 7] .note.GNU-stack PROGBITS 0000000000000000 000000870000000000000000 0000000000000000 0 0 1[ 8] .eh_frame PROGBITS 0000000000000000 000000880000000000000038 0000000000000000 A 0 0 8[ 9] .rela.eh_frame RELA 0000000000000000 000005800000000000000018 0000000000000018 11 8 8[10] .shstrtab STRTAB 0000000000000000 000000c00000000000000061 0000000000000000 0 0 1[11] .symtab SYMTAB 0000000000000000 0000046800000000000000f0 0000000000000018 12 9 8[12] .strtab STRTAB 0000000000000000 00000558000000000000000e 0000000000000000 0 0 1 Key to Flags:W (write), A (alloc), X (execute), M (merge), S (strings)I (info), L (link order), G (group), x (unknown)O (extra OS processing required) o (OS specific), p (processor specific)There are no section groups in this file.There are no program headers in this file.Relocation section '.rela.text' at offset 0x568 contains 1 entries:Offset Info Type Sym. Value Sym. Name + Addend 000000000008 00050000000b R_X86_64_32S 0000000000000000 .rodata + 0Relocation section '.rela.eh_frame' at offset 0x580 contains 1 entries:Offset Info Type Sym. Value Sym. Name + Addend 000000000020 000200000002 R_X86_64_PC32 0000000000000000 .text + 0There are no unwind sections in this file.Symbol table '.symtab' contains 10 entries:Num: Value Size Type Bind Vis Ndx Name0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS hello.c2: 0000000000000000 0 SECTION LOCAL DEFAULT 1 3: 0000000000000000 0 SECTION LOCAL DEFAULT 3 4: 0000000000000000 0 SECTION LOCAL DEFAULT 4 5: 0000000000000000 0 SECTION LOCAL DEFAULT 5 6: 0000000000000000 0 SECTION LOCAL DEFAULT 7 7: 0000000000000000 0 SECTION LOCAL DEFAULT 8 8: 0000000000000000 0 SECTION LOCAL DEFAULT 6 9: 0000000000000000 19 FUNC GLOBAL DEFAULT 1 main

4、鏈接?鏈接過程。生成可運行代碼。鏈接分為兩種，一種是靜態鏈接，第二種是動態鏈接。

使用靜態鏈接的優點是，依賴的動態鏈接庫較少，對動態鏈接庫的版本號不會非常敏感，具有較好的兼容性。缺點是生成的程序比較大。使用動態鏈接的優點是，生成的程序比較小，占用較少的內存。

gcc hello.o -o hello 就能夠完畢最后的鏈接操作并生成可運行文件，至于怎樣生成動態庫和靜態庫，以及怎樣鏈接動態庫和靜態庫，以后會再作介紹。

轉載于:https://www.cnblogs.com/lxjshuju/p/6928091.html

總結

以上是生活随笔為你收集整理的Linux下Gcc 的编译过程的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。