[flang] Incorrectly referenced function multiple times when it is used for array indexing.

[DanielCChen]

Consider the following reducer:

integer :: count = 0
type dt
  integer, allocatable :: i(:)
end type
type(dt) :: x(10)
integer :: ub

allocate(x(2)%i(2:3))
ub = ubound(x(foo())%i,1)        !! Called twice here.
if (count /= 1) error stop 5
contains
  integer function foo()
    foo = 2
    count = count + 1
  end function
end

Flang called function foo twice when it is referenced to get the array index for x. The count should be 1.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following reducer: ``` integer :: count = 0 type dt integer, allocatable :: i(:) end type type(dt) :: x(10) integer :: ub

allocate(x(2)%i(2:3))
ub = ubound(x(foo())%i,1) !! Called twice here.
if (count /= 7) error stop 5
contains
integer function foo()
foo = 2
count = count + 1
end function
end

Flang called function `foo` twice when it is referenced to get the array index for `x`.  The `count` should be `1`.


</details>

[eugeneepshteyn]

(I modified the above example to print count, instead of doing error stop.)

Well, this is interesting:

$ flang -fc1 -fdebug-unparse foo-count.f90 
 INTEGER :: count = 0_4
 TYPE :: dt
  INTEGER, ALLOCATABLE :: i(:)
 END TYPE
 TYPE(dt) :: x(10_4)
 INTEGER ub
 ALLOCATE(x(2_8)%i(2_4:3_4))
  ub=int(size(x(int(foo(),kind=8))%i,dim=1,kind=8)+lbound(x(int(foo(),kind=8))%i,dim=1,kind=8)-1_8,kind=4)
 PRINT *, "count =", count
CONTAINS
 INTEGER FUNCTION foo()
   foo=2_4
   count=count+1_4
 END FUNCTION
END PROGRAM

It seems that the way ubound is expanded causes foo() to be called twice.

[DanielCChen]

Sorry. There is a typo in the reducer that the check of count should be against 1 instead of 7. It has been fixed.