status of inter-class inlining in Java?

[Andrew Haley <aph at redhat dot com>]

Nathanael Nerode writes:
 > Consider the following sort of potential situation in libgcj:
 > 
 > class System {
 >   public static final foo() {
 >     B.foo();
 >   }
 > }
 > 
 > class VMSystem {
 >   static final foo() {
 >     ...
 >   }
 > }
 > 
 > Preferably VMSystem.foo should be inlined into System.foo during compilation.
 > (This would make it reasonable to merge a bunch more with Classpath, and
 > would more generally help with the indirection penalty caused by the rampant
 > forwarding methods used in much of Java.)
 > 
 > >From what I can tell, however, this doesn't seem to happen.

It works for me.


public class b
{
  public static int vvalue()
  {
    return 25;
  }
}


import b;

public class a
{
  public static void main (String[] argv)
  {
    System.out.println (b.vvalue());
  }
}


gcj a.java b.java -o bar -O3

Results in


a.main(java.lang.String[]):
.LFB4:
        pushl   %ebp
.LCFI9:
        movl    %esp, %ebp
.LCFI10:
        pushl   %ebx
.LCFI11:
        subl    20, %esp
.LCFI12:
        movl    a.class$, (%esp)
        call    _Jv_InitClass
        movl    java.lang.System.class$, (%esp)
        call    _Jv_InitClass
        movl    java.lang.System.out, %ebx
        movl    b.class$, (%esp)
        call    _Jv_InitClass
        movl    25, %edx
        movl    (%ebx), %eax
        movl    %edx, 4(%esp)
        movl    %ebx, (%esp)
        call    *100(%eax)
        addl    20, %esp
        popl    %ebx
        popl    %ebp
        ret

Andrew.