Uttam Pawar wrote:
> Hi All,
>
> I found following code snippet in file, trunk/gcc/loop-unroll.c
>
> 1814 /* Locate in EXPR the expression corresponding to the location
> recorded 1815 in IVTS, and return a pointer to the RTX for this
> location. */ 1816
> 1817 static rtx *
> 1818 get_ivts_expr (rtx expr, struct iv_to_split *ivts)
> 1819 {
> 1820 unsigned i;
> 1821 rtx *ret = &expr;
> 1822
> 1823 for (i = 0; i < ivts->n_loc; i++)
> 1824 ret = &XEXP (*ret, ivts->loc[i]);
> 1825
> 1826 return ret;
> 1827 }
>
> at line 1821, what is the point of taking address of a stack variable?
> and returning it, if the 'condition' in for loop fails. Is this done
> intentionally or is it an error?
The point is that it's only taking that pointer as the start of a linkedlist
chain down which it intends to run. As long as the loop runs at least once,
ret will point to a real rtx somewhere in heap memory. It would be a bug to
call get_ivts_expr if ivts->n_loc was zero, and it certainly wouldn't hurt to
add a gcc_assert() to that effect, but have you actually seen this routine
called with zero n_loc, or is it adequately guarded by the logic of the call
sites?
cheers,
DaveK
--
Can't think of a witty .sigline today....
