Richard Guenther <[email protected]> skribis:
> On Mon, Oct 8, 2012 at 3:32 PM, Ludovic Courtès <[email protected]> wrote:
>> Richard Guenther <[email protected]> skribis:
>>
>>> On Mon, Oct 8, 2012 at 1:42 PM, Ludovic Courtès <[email protected]> wrote:
>>>> Richard Guenther <[email protected]> skribis:
>>>>
>>>>> On Mon, Oct 8, 2012 at 11:58 AM, Ludovic Courtès <[email protected]> wrote:
>>>>>> Richard Guenther <[email protected]> skribis:
>>>>>>
>>>>>>> At -O0 no virtual operands are produced. TODO_rebuild_alias only
>>>>>>> computes
>>>>>>> points-to sets which are in itself not useful.
>>>>>>>
>>>>>>> What do you want to achieve with TODO_rebuild_alias?
>>>>>>
>>>>>> I basically want to use ‘ptr_derefs_may_alias_p’ in this particular pass.
>>>>>
>>>>> That should work.
>>>>
>>>> It actually does, except that ‘ptr_derefs_may_alias_p’ returns true for
>>>> two SSA names in cases like this:
>>>>
>>>> double *p, *q;
>>>> p = malloc (123);
>>>> q = malloc (234);
>>>>
>>>> (Where ‘malloc’ has the ‘malloc’ attribute.)
>>>>
>>>> For some reason, there’s no such false positive when using
>>>> TODO_rebuild_alias.
>>>
>>> Well, "that should work" means it works non-conservatively with
>>> TODO_rebuild_alias, of course.
>>
>> Right. :-) So how can I get maximum accuracy, while avoid the assertion
>> failure on -O0?
>
> You have to analyze the assert more. From the backtrace I cannot see
> anything suspicious.
The assert in ‘make_decl_rtl’ is:
gcc_assert (TREE_CODE (decl) != VAR_DECL
|| TREE_STATIC (decl)
|| TREE_PUBLIC (decl)
|| DECL_EXTERNAL (decl)
|| DECL_REGISTER (decl));
Upon inspection, ‘decl’ is VAR_DECL, but has all 4 flags above cleared.
In my example source file, the assertion is hit here:
numbers.c: In function ‘scm_c_make_polar’:
numbers.c:8728:10: internal compiler error: in make_decl_rtl, at varasm.c:1163
That line in numbers.c reads this:
sincos (ang, &s, &c);
And indeed, the dump of my pass (with -ftree-dump-all) reads this:
;; Function scm_c_make_polar (scm_c_make_polar)
Now a gimple register: D.26884
No longer having address taken: s
No longer having address taken: c
Symbols to be put in SSA form
{ s c D.26884 }
Incremental SSA update started at block: 0
Number of blocks in CFG: 8
Number of blocks to update: 7 ( 88%)
So it looks like there’s additional state corresponding to these
variables that needs updating?
Thanks,
Ludo’.
