Code Index 6 released

This time, I focus on for loop and repeating code.

FunctionLength

Test code:

void test_xxxxx_speed(int x){
  x+=x;
  x+=x;
  ... (repeat xxx times)
  x+=x;
  return x;  
}

Samsung Galaxy Note 2 run:

Linux OpenJDK 7 run:

com.luzi82.codeindex.FunctionLength START
test_00001_speed: 10.3M lines, 96.8ns/line
test_00010_speed: 103M lines, 9.67ns/line
test_00100_speed: 658M lines, 1.52ns/line
test_01000_speed: 1.33G lines, 751ps/line
test_10000_speed: 141M lines, 7.06ns/line
com.luzi82.codeindex.FunctionLength END

Observation:

• In Android, more repeating code is good.
• In OpenJDK, 1000 repeating code is good, 10000 repeating code is bad.
• Compiler does not allow me to do 100000 repeating code.

ForLoop

Test code:

void test_forloop_xxx_yy(){
  // when xxx=imm, use i--
  // when xxx=ipp, use i++
  // when xxx=mmi, use --i
  // when xxx=ppi, use ++i
  // when yy=gt/lt, use > / <
  // when yy=ne, use !=
  for(int i=0;i<1000;++i){
    x+=x;
  }
  return x;  
}

void test_repeat(){
  x+=x;
  x+=x;
  ... (repeat 1000 times)
  x+=x;
  return x;  
}

Samsung Galaxy Note 2 run:

Linux OpenJDK 7 run:

com.luzi82.codeindex.ForLoop START
test_forloop_imm_gt: 10.5G line/s, 94.6ps/line
test_forloop_imm_ne: 10.0G line/s, 99.4ps/line
test_forloop_ipp_lt: 10.5G line/s, 95.1ps/line
test_forloop_ipp_ne: 10.2G line/s, 98.0ps/line
test_forloop_mmi_gt: 10.0G line/s, 99.7ps/line
test_forloop_mmi_ne: 10.1G line/s, 98.8ps/line
test_forloop_ppi_lt: 10.4G line/s, 95.4ps/line
test_forloop_ppi_ne: 10.0G line/s, 99.0ps/line
test_repeat: 1.32G line/s, 759ps/line
com.luzi82.codeindex.ForLoop END

Observation:

• In for-loop, using i++ / ++i / i-- / --i does not affect much.
• In for-loop, using i<MAX / i!=MAX does not affect much.
• In Android, repeating code is faster.
• In OpenJDK, for-loop is faster.