On 21 April 2016 at 11:03, Richard Biener <richard.guent...@gmail.com> wrote:
> On Wed, Apr 20, 2016 at 5:08 PM, Bin Cheng <bin.ch...@arm.com> wrote:
>> Hi,
>> As reported in PR70715, GCC failed to prove no-overflows of IV(&p[n]) for
>> simple example like:
>> int
>> foo (char *p, unsigned n)
>> {
>> while(n--)
>> {
>> p[n]='A';
>> }
>> return 0;
>> }
>> Actually, code has already been added to handle this form loops when fixing
>> PR68529. Problem with this case is loop niter analyzer records control_IV
>> with its base expanded by calling expand_simple_operations. This patch
>> simply adds code expanding BASE before we check its equality against
>> control_IV.base. In the long run, we might want to remove the use of
>> expand_simple_operations.
>>
>> Bootstrap and test on x86_64. Is it OK?
>
Hi Bin,
On ARM and AArch64 bare-metal toolchains, this causes
FAIL: gcc.dg/tree-ssa/minmax-2.c scan-tree-dump optimized "__builtin_fmin"
Christophe
> Ok.
>
> Richard.
>
>> Thanks,
>> bin
>>
>>
>> 2016-04-20 Bin Cheng <bin.ch...@arm.com>
>>
>> PR tree-optimization/70715
>> * tree-ssa-loop-niter.c (loop_exits_before_overflow): Check equality
>> after expanding BASE using expand_simple_operations.
