from c to asm using (g)objdump

explanation.md

• execution

  $ gcc -g -c if_else.c
  $ gcc -g -c switch.c
  
  $ objdump -d -M intel -S if_else.o > if_else.asm  # Linux
  $ objdump -d -M intel -S switch.o > switch.asm
  
  $ gobjdump -d -M intel -S if_else.o > if_else.asm # OS X
  $ gobjdump -d -M intel -S switch.o > switch.asm
  

• installation

  $ brew install binutils # OS X
  ==> Downloading https://homebrew.bintray.com/bottles/binutils-2.25.yosemite.bottle.tar.gz
  ######################################################################## 100.0%
  ==> Pouring binutils-2.25.yosemite.bottle.tar.gz
  🍺  /usr/local/Cellar/binutils/2.25: 107 files, 140M
  

if_else.c

#include <stdio.h>

int main(int argc, char* argv[])  {
  int i, cnt = 0;
  for ( i = 0; i < 100000000; ++i )  {
    int j = i % 3;
    if ( j == 0 ) {
    } else if ( j == 1 )  {
      cnt += 1;
    } else  {
      cnt += 1;
    }
  }
  return 0;
}

switch.c

#include <stdio.h>

int main(int argc, char* argv[])  {
  int i, cnt = 0;
  for ( i = 0; i < 100000000; ++i )  {
    int j = i % 3;
    switch ( j )  {
      case 0:
        break;
      case 1:
        cnt += 1;
        break;
      default:
        cnt += 1;
        break;
    }
  }
  return 0;
}