2.95/3.x regression in the compilation of computed gotos?

[duchier@ps.uni-sb.de]

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Guys,

I'd like to get your opinion on the difference in how gcc 2.95 and
3.3.2 compile the line of code below (where PC has type void**):

	goto ** (PC += 1);

2.95:

	addl $4,%eax
        jmp *(%eax)

3.3.2:

	addl $4,%ecx
        movl (%ecx),%edx
        jmp *%edx

Isn't this a regression?

I attach below the short program used to illustrate this difference.
It reflects in a simplified manner what happens in our emulator for
mozart/oz threaded bytecode.


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void* program[2];
int counter = 0;

#define DISPATCH(N) goto **(PC+=N)

void foo (void** PC)
{
  if (PC==0) {
    program[0] = && one;
    program[1] = && two;
    return;
  }
  DISPATCH(0);
 one:
  counter += 3;
  DISPATCH(1);
 two:
  counter += 5;
  DISPATCH(1);
}

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Cheers,

-- 
Denys Duchier - Équipe Calligramme - LORIA, Nancy, France