llvm dev - Mar 2017 - Instruction Combine Cast (fptrunc (floor x)) -> (floor (fptrunc x))

Hi,

I have a test case would fail due to instruction combine cast
from floor to floorf.

double d = 1024.0 - 1.0 / 32768.0;
extern double floor(double);
extern float floorf(float);
extern void abort();

int main() {

    float f1 = (float)floor(d);

    if ((int)f1 != 1023)
      abort ();

    return 0;
}

My question is: Is the transformation legal for this case?

Thanks,
Shiva

Hi Shiva,

Thanks for reporting this. It looks like a bug to me (from r292855). Can 
you file a bug report? Matt, can you fix this?

  -Hal

On 03/16/2017 10:08 PM, Shiva Chen via llvm-dev wrote:
> Hi,
>
> I have a test case would fail due to instruction combine cast
> from floor to floorf.
>
> double d = 1024.0 - 1.0 / 32768.0;
> extern double floor(double);
> extern float floorf(float);
> extern void abort();
>
> int main() {
>
>      float f1 = (float)floor(d);
>
>      if ((int)f1 != 1023)
>        abort ();
>
>      return 0;
> }
>
> My question is: Is the transformation legal for this case?
>
> Thanks,
> Shiva
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory

> On Mar 17, 2017, at 06:31, Hal Finkel via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi Shiva,
> 
> Thanks for reporting this. It looks like a bug to me (from r292855). Can
you file a bug report? Matt, can you fix this?
> 
> -Hal
https://reviews.llvm.org/D31107