[Bug tree-optimization/66823] New: -ftree-loop-if-convert-stores miscompiles gfortran.dg/elemental_optional_args_3.f90

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66823

            Bug ID: 66823
           Summary: -ftree-loop-if-convert-stores miscompiles
                    gfortran.dg/elemental_optional_args_3.f90
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---
            Target: i?86-*-*

On x86_64 with -m32/-ftree-loop-if-convert-stores I see

FAIL: gfortran.dg/elemental_optional_args_3.f90   -O3 -fomit-frame-pointer 
execution test
FAIL: gfortran.dg/elemental_optional_args_3.f90   -O3 -fomit-frame-pointer
-funroll-loops  execution test
FAIL: gfortran.dg/elemental_optional_args_3.f90   -O3 -fomit-frame-pointer
-funroll-all-loops -finline-functions  execution test
FAIL: gfortran.dg/elemental_optional_args_3.f90   -O3 -g  execution test

if-conversion changes

 if (p != 0)
  val = *p;
 else
  val = 1;

to

 tem = *p;
 val = p != 0 ? tem : 1;