Different dynamical array debug info 7.2 vs. 8.0

[Yao Qi <qiyaoltc at gmail dot com>]

Hi,
I observed that gfortran 7.2 and 8.0 generate different debug info for
dynamical array.  Here is a case simplified from gdb test case
gdb.fortran/vla-datatypes.f90

$ cat vla-datatypes.f90 
program vla_primitives
  integer, allocatable    :: intvla(:, :, :)
  logical                 :: l

  allocate (intvla (11,22,33))

  l = allocated(intvla)                   ! vlas-allocated
  intvla(:,:,:) = 1
  intvla(5,5,5) = 42                      ! vlas-initialized
end program vla_primitives


In gcc 8.0, the intvla debug info is,

 <2><b2>: Abbrev Number: 10 (DW_TAG_variable)
    <b3>   DW_AT_name        : (indirect string, offset: 0xcb): intvla
    <b7>   DW_AT_decl_file   : 1
    <b8>   DW_AT_decl_line   : 2
    <b9>   DW_AT_type        : <0x127>
    <bd>   DW_AT_location    : 3 byte block: 91 e0 7e   (DW_OP_fbreg: -160)

 <1><127>: Abbrev Number: 14 (DW_TAG_array_type)
    <128>   DW_AT_ordering    : 1       (column major)
    <129>   DW_AT_data_location: 4 byte block: 97 23 8 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 8; DW_OP_deref)
    <12e>   DW_AT_allocated   : 6 byte block: 97 23 8 6 30 2e   (DW_OP_push_object_address; DW_OP_plus_uconst: 8; DW_OP_deref; DW_OP_lit0; DW_OP_ne)
    <135>   DW_AT_type        : <0x7b>
    <139>   DW_AT_sibling     : <0x174>
 <2><13d>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <13e>   DW_AT_lower_bound : 4 byte block: 97 23 28 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 40; DW_OP_deref)
    <143>   DW_AT_upper_bound : 4 byte block: 97 23 30 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 48; DW_OP_deref)
    <148>   DW_AT_byte_stride : 6 byte block: 97 23 20 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 32; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><14f>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <150>   DW_AT_lower_bound : 4 byte block: 97 23 40 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 64; DW_OP_deref)
    <155>   DW_AT_upper_bound : 4 byte block: 97 23 48 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 72; DW_OP_deref)
    <15a>   DW_AT_byte_stride : 6 byte block: 97 23 38 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 56; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><161>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <162>   DW_AT_lower_bound : 4 byte block: 97 23 58 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 88; DW_OP_deref)
    <167>   DW_AT_upper_bound : 4 byte block: 97 23 60 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 96; DW_OP_deref)
    <16c>   DW_AT_byte_stride : 6 byte block: 97 23 50 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 80; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><173>: Abbrev Number: 0

In gcc 7.2, it is,

 <2><b2>: Abbrev Number: 10 (DW_TAG_variable)
    <b3>   DW_AT_name        : (indirect string, offset: 0x12): intvla
    <b7>   DW_AT_decl_file   : 1
    <b8>   DW_AT_decl_line   : 2
    <b9>   DW_AT_type        : <0x127>
    <bd>   DW_AT_location    : 3 byte block: 91 e0 7e   (DW_OP_fbreg: -160)

 <1><127>: Abbrev Number: 14 (DW_TAG_array_type)
    <128>   DW_AT_ordering    : 1       (column major)
    <129>   DW_AT_data_location: 2 byte block: 97 6     (DW_OP_push_object_address; DW_OP_deref)
    <12c>   DW_AT_allocated   : 4 byte block: 97 6 30 2e        (DW_OP_push_object_address; DW_OP_deref; DW_OP_lit0; DW_OP_ne)
    <131>   DW_AT_type        : <0x7b>
    <135>   DW_AT_sibling     : <0x170>
 <2><139>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <13a>   DW_AT_lower_bound : 4 byte block: 97 23 20 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 32; DW_OP_deref)
    <13f>   DW_AT_upper_bound : 4 byte block: 97 23 28 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 40; DW_OP_deref)
    <144>   DW_AT_byte_stride : 6 byte block: 97 23 18 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 24; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><14b>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <14c>   DW_AT_lower_bound : 4 byte block: 97 23 38 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 56; DW_OP_deref)
    <151>   DW_AT_upper_bound : 4 byte block: 97 23 40 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 64; DW_OP_deref)
    <156>   DW_AT_byte_stride : 6 byte block: 97 23 30 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 48; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><15d>: Abbrev Number: 15 (DW_TAG_subrange_type)
    <15e>   DW_AT_lower_bound : 4 byte block: 97 23 50 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 80; DW_OP_deref)
    <163>   DW_AT_upper_bound : 4 byte block: 97 23 58 6        (DW_OP_push_object_address; DW_OP_plus_uconst: 88; DW_OP_deref)
    <168>   DW_AT_byte_stride : 6 byte block: 97 23 48 6 34 1e  (DW_OP_push_object_address; DW_OP_plus_uconst: 72; DW_OP_deref; DW_OP_lit4; DW_OP_mul)
 <2><16f>: Abbrev Number:

Attributes DW_AT_data_location and DW_AT_allocated are different.  There
is an extra "DW_OP_plus_uconst: 8" generated by gcc 8.0.  Is it
intended or expected?  gfortran 8.0 causes many gdb.fotran vla-related
tests fail, but gfortran 7.2 doesn't.  That is why I took a look at the
debug information.

-- 
Yao (齐尧)