mfence on i686 with volatile?

[Dennis Byrne]

I am not observing any fences in the output from PrintAssembly.  The
following java produces the following assembly, regardless of whether
or not I make v and v2 volatile.

class HelloWorld extends Thread{
  public static int v = 0;
  public static int v2 = 1;
  public static void main(String[] args){
	new HelloWorld().start();
	new HelloWorld().start();
  }
  public void run() {
       for(int i = 0; i < 1000000; i++){
		v += 333;
		v2 += v;
       }
       System.out.println(v);
       System.out.println(v2);
  }
}


  0x02e33d30: mov	%eax,-0x3000(%esp) ;
  0x02e33d37: push	%ebp               	        ;
  0x02e33d38: mov	%esp,%ebp          	;
  0x02e33d3a: sub	$0x28,%esp         	;
  0x02e33d3d: mov	$0x0,%esi          	;
  0x02e33d42: jmp	0x02e33d7a         	;
  0x02e33d47: nop				        ;
  0x02e33d48: mov	$0x95ba5348,%edx   	;

  0x02e33d4d: mov	0x1b8(%edx),%ecx   	;
  0x02e33d53: add	$0x14d,%ecx        	; v += 333
  0x02e33d59: mov	%ecx,0x1b8(%edx)   	;
  0x02e33d5f: mov	0x1bc(%edx),%ecx   	;
  0x02e33d65: mov	0x1b8(%edx),%edi   	;
  0x02e33d6b: add	%edi,%ecx          	; v2 += v
  0x02e33d6d: mov	%ecx,0x1bc(%edx)   	;
  0x02e33d73: inc	%esi               	        ; i++
                                        	;
                                        	;
                                        	; - HelloWorld::run at 31 (line 12)


-- 
Dennis Byrne