Clemens Kolbitsch wrote:
> /* XXX: index == 4 is always invalid */
> if (havesib && (index != 4 || scale != 0)) {
> #ifdef TARGET_X86_64
> if (s->aflag == 2) {
> gen_op_addq_A0_reg_sN(scale, index);
> } else
> #endif
> {
> /// !!!!!!!!!! this does the evil !!!!!!!!!!!!!!
> gen_op_addl_A0_reg_sN(scale, index);
> }
> }
This is indeed a bug. Avi's explained why it doesn't trigger in
normal code.
When the index register is 4, which normally means %esp, in the SIB
encoding it means "no index". Independent of the shift (scale).
So it should say:
/* index == 4 means no index. */
if (havesib && index != 4) {
But that said, I'm not sure if this line from earlier breaks the test:
index = ((code >> 3) & 7) | REX_X(s);
When is REX_X(s) not zero, and does it break the index != 4 test?
-- Jamie
