[flang][debug] Missing upper bound for adjustable array

[jiel-nv]

Consider the following code,

subroutine bar(adj, n, m)
  integer n, m
  real*8 adj(n:m)
  adj(n) = 7
end subroutine

program test
  real*8 foo(100)
  call bar(foo, 101, 200)
  print *, foo(1)
end program

flang version 20.0.0 (https://github.com/llvm/llvm-project a2fb70523ac310af6d8a4d9663dfe7c9cd370c53)
Compile with Flang, no upper bound info in GDB

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4         adj(n) = 7
(gdb) ptype adj
type = real (101:*)

Compile with GFortran gives,

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4         adj(n) = 7
(gdb) ptype adj
type = real(kind=8) (101:200)

The problem is that neither DW_AT_upper_bound nor DW_AT_count is emitted for array adj in the DWARF.

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: JL (jieljiel)

Consider the following code, ``` subroutine bar(adj, n, m) integer n, m real*8 adj(n:m) adj(n) = 7 end subroutine

program test
real*8 foo(100)
call bar(foo, 101, 200)
print *, foo(1)
end program

`flang version 20.0.0 (https://github.com/llvm/llvm-project a2fb70523ac310af6d8a4d9663dfe7c9cd370c53)`
Compile with flang, no upper bound info in gdb

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4 adj(n) = 7
(gdb) ptype adj
type = real (101:*)

Compile with gfortran gives,

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4 adj(n) = 7
(gdb) ptype adj
type = real(kind=8) (101:200)

The problem is that neither DW_AT_upper_bound nor DW_AT_count is emitted for array `adj` in the DWARF.

</details>

[llvmbot]

@llvm/issue-subscribers-flang-ir

Author: JL (jieljiel)

Consider the following code, ``` subroutine bar(adj, n, m) integer n, m real*8 adj(n:m) adj(n) = 7 end subroutine

program test
real*8 foo(100)
call bar(foo, 101, 200)
print *, foo(1)
end program

`flang version 20.0.0 (https://github.com/llvm/llvm-project a2fb70523ac310af6d8a4d9663dfe7c9cd370c53)`
Compile with flang, no upper bound info in gdb

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4 adj(n) = 7
(gdb) ptype adj
type = real (101:*)

Compile with gfortran gives,

Breakpoint 1, bar (adj=..., n=101, m=200) at bug.f90:4
4 adj(n) = 7
(gdb) ptype adj
type = real(kind=8) (101:200)

The problem is that neither DW_AT_upper_bound nor DW_AT_count is emitted for array `adj` in the DWARF.

</details>

[abidh]

It seems that flang is generating the expected debug information but backend drops one of the the artificial variable that contains the extent of the array. I also noticed that if I just add a print statement at the end of bar function as shown below, the debug information is not dropped and the bounds are shown correctly by the debugger.

subroutine bar(adj, n, m)
  integer n, m
  real*8 adj(n:m)
  adj(n) = 7
  print *, adj
end subroutine