| Issue |
139754
|
| Summary |
[flang] Behavior of gfortran test depends on optimization level: pr117797.f90
|
| Labels |
flang
|
| Assignees |
|
| Reporter |
tarunprabhu
|
Steps to reproduce:
Assuming that the [LLVM test suite](https://github.com/llvm/llvm-test-suite) is checked out in ./llvm-test-suite, compile the test at various optimization levels
```
$ flang -o a0.out -O0 ./llvm-test-suite/Fortran/gfortran/regression/pr117797.f90
$ flang -o a1.out -O1 ./llvm-test-suite/Fortran/gfortran/regression/pr117797.f90
$ flang -o a2.out -O2 ./llvm-test-suite/Fortran/gfortran/regression/pr117797.f90
$ flang -o a3.out -O3 ./llvm-test-suite/Fortran/gfortran/regression/pr117797.f90
$ flang -o alto.out -flto=auto ./llvm-test-suite/Fortran/gfortran/regression/pr117797.f90
```
When these are run, the executables created with `-O0` and `-flto=auto` encounter a `STOP` statement in the code, but those compiled with optimizations do not.
```
$ ./a0.out
Fortran STOP: code 2
$ ./a1.out
$ ./a2.out
$ ./a3.out
$ ./alto.out
Fortran STOP: code 2
```
Expected behavior: The stop message should never be printed.
What follows is a slightly reduced code that reproduces this behavior. If the `class default` branch of the `select` statement is removed, the `STOP` message is printed at all optimization levels.
```
module foo
type, public :: any_matrix
class(*), allocatable :: value(:,:)
end type
contains
function bar(this) result(uptr)
class(any_matrix), target, intent(in) :: this
class(*), pointer :: uptr(:,:)
uptr => this%value ! Seg. fault in trans-array.cc(gfc_get_array_span) here
end function
function build(this) result (res)
class(*) :: this(:,:)
type(any_matrix) :: res
res%value = this
end function
function evaluate (this) result (res)
class(*) :: this(:,:)
character(len = 2, kind = 1), allocatable :: res(:)
select type (ans => this)
type is (character(*))
res = reshape (ans, [4])
type is (integer)
allocate (res (8))
write (res, '(i2)') ans
class default
res = ['no','t ','OK','!!']
end select
end
end module
use foo
class(*), allocatable :: up (:, :)
integer :: i(2,2) = reshape ([1,2,3,4], [2,2])
up = bar (build (i))
if (any (evaluate (up) /= [' 1',' 2',' 3',' 4'])) stop 2
deallocate (up)
end
```
The cases in the `SELECT` statement seem to have an effect on the behavior. Removing only the `character(*)` case results in correct behavior at all optimization levels. Removing only the `class default` cases causes the error to occur only at `-O0` but not at any other optimization level.
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