生成有详细信息的汇编文件

例子

#include <stdio.h>

int main(void)
{
  int i;

  for (i = 0; i < 10; i++)
    printf("%d ", i);
  putchar ('\n');

  return 0;
}

技巧

使用-fverbose-asm选项就可以生成带有详细信息的汇编文件：

$ gcc -S -fverbose-asm foo.c
$ cat foo.s
    .file    "foo.c"
# GNU C (Ubuntu/Linaro 4.6.3-1ubuntu5) version 4.6.3 (x86_64-linux-gnu)
#    compiled by GNU C version 4.6.3, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9
# GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
# options passed:  -imultilib . -imultiarch x86_64-linux-gnu foo.c
# -mtune=generic -march=x86-64 -fverbose-asm -fstack-protector
# options enabled:  -fasynchronous-unwind-tables -fauto-inc-dec
# -fbranch-count-reg -fcommon -fdelete-null-pointer-checks -fdwarf2-cfi-asm
# -fearly-inlining -feliminate-unused-debug-types -ffunction-cse -fgcse-lm
# -fident -finline-functions-called-once -fira-share-save-slots
# -fira-share-spill-slots -fivopts -fkeep-static-consts
# -fleading-underscore -fmath-errno -fmerge-debug-strings
# -fmove-loop-invariants -fpeephole -fprefetch-loop-arrays
# -freg-struct-return -fsched-critical-path-heuristic
# -fsched-dep-count-heuristic -fsched-group-heuristic -fsched-interblock
# -fsched-last-insn-heuristic -fsched-rank-heuristic -fsched-spec
# -fsched-spec-insn-heuristic -fsched-stalled-insns-dep -fshow-column
# -fsigned-zeros -fsplit-ivs-in-unroller -fstack-protector
# -fstrict-volatile-bitfields -ftrapping-math -ftree-cselim -ftree-forwprop
# -ftree-loop-if-convert -ftree-loop-im -ftree-loop-ivcanon
# -ftree-loop-optimize -ftree-parallelize-loops= -ftree-phiprop -ftree-pta
# -ftree-reassoc -ftree-scev-cprop -ftree-slp-vectorize
# -ftree-vect-loop-version -funit-at-a-time -funwind-tables
# -fvect-cost-model -fverbose-asm -fzero-initialized-in-bss
# -m128bit-long-double -m64 -m80387 -maccumulate-outgoing-args
# -malign-stringops -mfancy-math-387 -mfp-ret-in-387 -mglibc -mieee-fp
# -mmmx -mno-sse4 -mpush-args -mred-zone -msse -msse2 -mtls-direct-seg-refs

# Compiler executable checksum: 75e879ed14f91af504f4150eadeaa0e6

    .section    .rodata
.LC0:
    .string    "%d "
    .text
    .globl    main
    .type    main, @function
main:
.LFB0:
    .cfi_startproc
    pushq    %rbp    #
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp    #,
    .cfi_def_cfa_register 6
    subq    $16, %rsp    #,
    movl    $0, -4(%rbp)    #, i
    jmp    .L2    #
.L3:
    movl    $.LC0, %eax    #, D.2049
    movl    -4(%rbp), %edx    # i, tmp62
    movl    %edx, %esi    # tmp62,
    movq    %rax, %rdi    # D.2049,
    movl    $0, %eax    #,
    call    printf    #
    addl    $1, -4(%rbp)    #, i
.L2:
    cmpl    $9, -4(%rbp)    #, i
    jle    .L3    #,
    movl    $10, %edi    #,
    call    putchar    #
    movl    $0, %eax    #, D.2050
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size    main, .-main
    .ident    "GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3"
    .section    .note.GNU-stack,"",@progbits

可以看到，在汇编文件中给出了gcc所使用的具体选项，以及汇编指令操作数所对应的源程序（或中间代码）中的变量。

详情参见gcc手册

贡献者

xmj