GCC trunk SPEC2000 performance

[law@redhat.com]

In message <200206202029.QAA24412@makai.watson.ibm.com>, David Edelsohn writes:
 > >>>>> Graham Stott writes:
 > 
 > Graham> That all depends if a MEM rtx should ever appear in x_regno_reg_rtx[
 > ]
 > 
 > Graham> I can't tell for sure because there's no comment describing this fie
 > ld
 > Graham> in integrate.h and a quick grep is not conclusive most of the uses I
 > Graham> examined implied it was always a REG rtx but in a few cases there is
 > Graham> code such as
 > 
 > Graham> if (GET_CODE (regno_reg_rtx[regno]) != REG)
 > 
 > Graham> which tends to imply it might sometimes not be a REG rtx.
 > 
 > 	reload1.c has the comment:
 > 
 >   /* If the reg got changed to a MEM at rtl-generation time,
 >      ignore it.  */
 >   if (GET_CODE (regno_reg_rtx[i]) != REG)
 >     return;
 > 
 > which strongly implies that the array can contain MEMs created at RTL
 > generation, so assuming that the array only contains REGs is incorrect.
Quite possibly.  Though do you see why nobody's reviewed the patch -- Jan
didn't provide any of this kind of technical information which is crucial
to knowing if his patch is correct or not.

And even if we have now decided that MEMs can appear in the reg array, then
we need to have that documented in comments as it's certainly counterintuitive.

jeff