We need to rebuild frequency after vrp, otherwise the following code
in tree-ssa-threadupdate.c will make the frequency larger than
upper-bound.
/* Excessive jump threading may make frequencies large enough so
the computation overflows. */
if (rd->dup_blocks[0]->frequency < BB_FREQ_MAX * 2)
rd->dup_blocks[0]->frequency += EDGE_FREQUENCY (e);
This is referring to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61384
Thanks,
Dehao
On Mon, Jun 2, 2014 at 9:13 AM, Jan Hubicka <hubi...@ucw.cz> wrote:
>> This patch rebuilds frequency after vrp.
>
> Why do you need to rebuild frequency after VRP? I always tought it may be
> useful to do VRP as early optimization (modulo to compile time costs),
> but I do not think we should unconditionally rebuild frequencies like this...
>
> Honza
>>
>> Bootstrapped and testing on-going. OK for trunk if test pass?
>>
>> Thanks,
>> Dehao
>>
>> gcc/ChangeLog:
>> 2014-06-02 Dehao Chen <de...@google.com>
>>
>> PR tree-optimization/61384
>> * tree-vrp.c (execute_vrp): rebuild frequency after vrp.
>>
>> gcc/testsuite/ChangeLog:
>> 2014-06-02 Dehao Chen <de...@google.com>
>>
>> PR tree-optimization/61384
>> * gcc.dg/pr61384.c: New testcase.
>>
>> Index: gcc/testsuite/gcc.dg/pr61384.c
>> ===================================================================
>> --- gcc/testsuite/gcc.dg/pr61384.c (revision 0)
>> +++ gcc/testsuite/gcc.dg/pr61384.c (revision 0)
>> @@ -0,0 +1,32 @@
>> +/* PR tree-optimization/61384 */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O3" } */
>> +
>> +int a, b, d, e, g, h;
>> +static int c = 1, f[5];
>> +
>> +int
>> +fn1 (int p1, int p2)
>> +{
>> + return p1 && p2 && p2;
>> +}
>> +
>> +void
>> +fn2 ()
>> +{
>> + for (d = 0; d < 1; d++)
>> + {
>> + g = f[0];
>> + e = 0;
>> + h = fn1 (1, (a && c) ^ b);
>> + }
>> + for (; e < 5; e++)
>> + f[e] = 1;
>> +}
>> +
>> +int
>> +main ()
>> +{
>> + fn2 ();
>> + return 0;
>> +}
>>
>> Index: gcc/tree-vrp.c
>> ===================================================================
>> --- gcc/tree-vrp.c (revision 211137)
>> +++ gcc/tree-vrp.c (working copy)
>> @@ -9794,7 +9794,7 @@ execute_vrp (void)
>>
>> scev_finalize ();
>> loop_optimizer_finalize ();
>> - return 0;
>> + return TODO_rebuild_frequencies;
>> }
>>
>> namespace {
