Why Java is running faster than C here?

I expect javac is defaulting to some higher level of optimization than your C compiler. When I compile with -O3 here, the C is way faster:

C with -O3:

real    0m0.003s
user    0m0.000s
sys     0m0.002s

Your java program:

real    0m0.294s
user    0m0.269s
sys     0m0.051s

Some more details; without optimization, the C compiles to:

0000000100000f18 pushq %rbp
0000000100000f19 movq %rsp,%rbp
0000000100000f1c movl %edi,0xec(%rbp)
0000000100000f1f movq %rsi,0xe0(%rbp)
0000000100000f23 movl $0x00000000,0xfc(%rbp)
0000000100000f2a incl 0xfc(%rbp)
0000000100000f2d movl $0x80000000,%eax
0000000100000f32 cmpl %eax,0xfc(%rbp)
0000000100000f35 jne  0x00000f2a
0000000100000f37 movl $0x00000000,%eax
0000000100000f3c leave
0000000100000f3d ret

With optimization (-O3), it looks like this:

0000000100000f30 pushq %rbp
0000000100000f31 movq %rsp,%rbp
0000000100000f34 xorl %eax,%eax
0000000100000f36 leave
0000000100000f37 ret

As you can see, the entire loop has been removed. javap -c Loop gave me this output for the java bytecode:

public static void main(java.lang.String[]);
  Code:
   0:   iconst_0
   1:   istore_1
   2:   iload_1
   3:   iinc    1, 1
   6:   ldc #2; //int 2147483647
   8:   if_icmpge   14
   11:  goto    2
   14:  return

}

It appears the loop is compiled in, I guess something happens at runtime to speed that one up. (As others have mentioned, the JIT compiler squashes out the loop.)

My guess is that the JIT is optimizing away the empty loop.

Update: The Java Performance Tuning article Followup to Empty Loop Benchmark seems to support that, along with the other answers here that point out that the C code needs to also be optimized in order to make a meaningful comparison. Key quote:

Had I chosen to use the client mode 1.4.1 JVM (client is the default mode), the loops would not be optimized away. Had I chosen to use Microsoft's C++ compiler, the C version would take no time. Clearly, the choice of compiler is critical.

There are some things you need to control for here:

• the startup of the JVM is nontrivial compared to startup of a compiled C program
• your loop isn't doing anything, and the compiler probably knows that
• JIT compilers often produce better code than a non-optimised C compiler