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Kumar N, Bhuvanendra via llvm-dev

2021-Jul-27 13:58 UTC

[llvm-dev] [DebugInfo] Fortran namelist support

[AMD Official Use Only]

Hello Everyone,

I am planning to implement the LLVM changes for fortran NAMELIST feature from
DebugInfo point of view.

gfortran already support namelist from DebugInfo point of view, it emits
DW_TAG_namelist and DW_TAG_namelist_item die's as shown below. But gdb does
not understand these, hence we enhanced gdb to handle namelist variable/type.
Soon upstreaming the gdb code changes.

In order to emit the DW_TAG_namelist and DW_TAG_namelist_item die's in LLVM,
following LLVM IR changes are proposed, could you please review and comment if
any change is required. Namelist in fortran is basically group of variables or
arrays. It can be represented as composite type. Already Metadata is created for
each of the namelist items like !20, !22 in the below example, we just need to
reference to these while handling DW_TAG_namelist_item. This proposal looks
simple and uses the existing composite type with a new tag:DW_TAG_namelist.
Please let me know if you have any comments or need more information on these.

NOTE: Currently flang also does not emit any metadata to handle namelist
DebugInfo. flang code changes for the same will be taken up after the LLVM
support for namelist.

Proposed LLVM IR changes for namelist DebugInfo handling (for the sample fortran
program shown below):
. . .
!20 = !DILocalVariable(scope: !15, name: "a", file: !3, line: 6, type:
!19)
. . .
!22 = !DILocalVariable(scope: !15, name: "b", file: !3, line: 7, type:
!19)
. . .
!24 = !{ !26, !27 }
!25 = !DICompositeType(tag: DW_TAG_namelist, file: !3, name: "nml",
elements: !24)
!26 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !20)
!27 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !22)
. . .

Thanks and regards,
Bhuvan

Sample program :

program main
  integer :: a, b
  namelist /nml/ a, b

  a = 10
  b = 20
  Write(*,nml)
end program main

dwarfdump of an gfortran emitted binary :
. . .
0x000000b4:     DW_TAG_variable [10]
                  DW_AT_name [DW_FORM_string]   ("a")
                  DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
                  DW_AT_decl_line [DW_FORM_data1]       (20)
                  DW_AT_type [DW_FORM_ref4]     (cu + 0x006d => {0x0000006d}
"integer(kind=4)")
                  DW_AT_declaration [DW_FORM_flag_present]      (true)
                  DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -20)

0x000000c0:     DW_TAG_variable [10]
                  DW_AT_name [DW_FORM_string]   ("b")
                  DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
                  DW_AT_decl_line [DW_FORM_data1]       (20)
                  DW_AT_type [DW_FORM_ref4]     (cu + 0x006d => {0x0000006d}
"integer(kind=4)")
                  DW_AT_declaration [DW_FORM_flag_present]      (true)
                  DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -24)
. . .
0x000000dd:     DW_TAG_namelist [12] *
                  DW_AT_name [DW_FORM_string]   ("nml")

0x000000e2:       DW_TAG_namelist_item [9]
                    DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00b4 =>
{0x000000b4})

0x000000e7:       DW_TAG_namelist_item [9]
                    DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00c0 =>
{0x000000c0})

0x000000ec:       NULL

Sample GDB commands output (GDB used here is internal, soon it will be
upstreamed) :

(gdb) ptype nml
type = Type nml
    integer(kind=4) :: a
    integer(kind=4) :: b
End Type nml

(gdb) print nml
$1 = ( a = 10, b = 20 )
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Adrian Prantl via llvm-dev

2021-Jul-27 15:36 UTC

head link

[llvm-dev] [DebugInfo] Fortran namelist support

> On Jul 27, 2021, at 6:58 AM, Kumar N, Bhuvanendra via llvm-dev <llvm-dev
at lists.llvm.org> wrote:
> 
> [AMD Official Use Only]
> 
> Hello Everyone,
>  
> I am planning to implement the LLVM changes for fortran NAMELIST feature
from DebugInfo point of view.
>  
> gfortran already support namelist from DebugInfo point of view, it emits
DW_TAG_namelist and DW_TAG_namelist_item die's as shown below. But gdb does
not understand these, hence we enhanced gdb to handle namelist variable/type.
Soon upstreaming the gdb code changes.
>  
> In order to emit the DW_TAG_namelist and DW_TAG_namelist_item die's in
LLVM, following LLVM IR changes are proposed, could you please review and
comment if any change is required. Namelist in fortran is basically group of
variables or arrays. It can be represented as composite type. Already Metadata
is created for each of the namelist items like !20, !22 in the below example, we
just need to reference to these while handling DW_TAG_namelist_item. This
proposal looks simple and uses the existing composite type with a new
tag:DW_TAG_namelist. Please let me know if you have any comments or need more
information on these.
>  
> NOTE: Currently flang also does not emit any metadata to handle namelist
DebugInfo. flang code changes for the same will be taken up after the LLVM
support for namelist.
>  
> Proposed LLVM IR changes for namelist DebugInfo handling (for the sample
fortran program shown below):
> . . .
> !20 = !DILocalVariable(scope: !15, name: "a", file: !3, line: 6,
type: !19)
> . . .
> !22 = !DILocalVariable(scope: !15, name: "b", file: !3, line: 7,
type: !19)
> . . .
> !24 = !{ !26, !27 }
> !25 = !DICompositeType(tag: DW_TAG_namelist, file: !3, name:
"nml", elements: !24)
> !26 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !20)
> !27 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !22)
> . . .
The DICompositeType looks reasonable, I'm not sure why the DIDerivedType is
necessary. Wouldn't it be simpler to just use an MDList "elements:
!{20, !22}"?

-- adrian
>  
> Thanks and regards,
> Bhuvan
>  
> Sample program :
>  
> program main
>   integer :: a, b
>   namelist /nml/ a, b
>  
>   a = 10
>   b = 20
>   Write(*,nml)
> end program main
>  
> dwarfdump of an gfortran emitted binary :
> . . .
> 0x000000b4:     DW_TAG_variable [10]
>                   DW_AT_name [DW_FORM_string]   ("a")
>                   DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
>                   DW_AT_decl_line [DW_FORM_data1]       (20)
>                   DW_AT_type [DW_FORM_ref4]     (cu + 0x006d =>
{0x0000006d} "integer(kind=4)")
>                   DW_AT_declaration [DW_FORM_flag_present]      (true)
>                   DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -20)
>  
> 0x000000c0:     DW_TAG_variable [10]
>                   DW_AT_name [DW_FORM_string]   ("b")
>                   DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
>                   DW_AT_decl_line [DW_FORM_data1]       (20)
>                   DW_AT_type [DW_FORM_ref4]     (cu + 0x006d =>
{0x0000006d} "integer(kind=4)")
>                   DW_AT_declaration [DW_FORM_flag_present]      (true)
>                   DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -24)
> . . .
> 0x000000dd:     DW_TAG_namelist [12] *
>                   DW_AT_name [DW_FORM_string]   ("nml")
>  
> 0x000000e2:       DW_TAG_namelist_item [9]
>                     DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00b4 =>
{0x000000b4})
>  
> 0x000000e7:       DW_TAG_namelist_item [9]
>                     DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00c0 =>
{0x000000c0})
>  
> 0x000000ec:       NULL
>  
> Sample GDB commands output (GDB used here is internal, soon it will be
upstreamed) :
>  
> (gdb) ptype nml
> type = Type nml
>     integer(kind=4) :: a
>     integer(kind=4) :: b
> End Type nml
>  
> (gdb) print nml
> $1 = ( a = 10, b = 20 )
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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Kumar N, Bhuvanendra via llvm-dev

2021-Aug-23 13:51 UTC

head link

[llvm-dev] [DebugInfo] Fortran namelist support

[Public]

Thanks a lot for the suggestion. I followed it and just raised the review
request (https://reviews.llvm.org/D108553)

regards,
bhuvan

From: Adrian Prantl <aprantl at apple.com>
Sent: Tuesday, July 27, 2021 9:07 PM
To: Kumar N, Bhuvanendra <Bhuvanendra.KumarN at amd.com>
Cc: llvm-dev <llvm-dev at lists.llvm.org>; George, Jini Susan
<JiniSusan.George at amd.com>; Sharma, Alok Kumar <AlokKumar.Sharma at
amd.com>; Balasubrmanian, Vignesh <Vignesh.Balasubrmanian at amd.com>
Subject: Re: [llvm-dev] [DebugInfo] Fortran namelist support

[CAUTION: External Email]


On Jul 27, 2021, at 6:58 AM, Kumar N, Bhuvanendra via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

[AMD Official Use Only]

Hello Everyone,

I am planning to implement the LLVM changes for fortran NAMELIST feature from
DebugInfo point of view.

gfortran already support namelist from DebugInfo point of view, it emits
DW_TAG_namelist and DW_TAG_namelist_item die's as shown below. But gdb does
not understand these, hence we enhanced gdb to handle namelist variable/type.
Soon upstreaming the gdb code changes.

In order to emit the DW_TAG_namelist and DW_TAG_namelist_item die's in LLVM,
following LLVM IR changes are proposed, could you please review and comment if
any change is required. Namelist in fortran is basically group of variables or
arrays. It can be represented as composite type. Already Metadata is created for
each of the namelist items like !20, !22 in the below example, we just need to
reference to these while handling DW_TAG_namelist_item. This proposal looks
simple and uses the existing composite type with a new tag:DW_TAG_namelist.
Please let me know if you have any comments or need more information on these.

NOTE: Currently flang also does not emit any metadata to handle namelist
DebugInfo. flang code changes for the same will be taken up after the LLVM
support for namelist.

Proposed LLVM IR changes for namelist DebugInfo handling (for the sample fortran
program shown below):
. . .
!20 = !DILocalVariable(scope: !15, name: "a", file: !3, line: 6, type:
!19)
. . .
!22 = !DILocalVariable(scope: !15, name: "b", file: !3, line: 7, type:
!19)
. . .
!24 = !{ !26, !27 }
!25 = !DICompositeType(tag: DW_TAG_namelist, file: !3, name: "nml",
elements: !24)
!26 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !20)
!27 = !DIDerivedType(tag: DW_TAG_namelist_item, item: !22)
. . .

The DICompositeType looks reasonable, I'm not sure why the DIDerivedType is
necessary. Wouldn't it be simpler to just use an MDList "elements:
!{20, !22}"?

-- adrian


Thanks and regards,
Bhuvan

Sample program :

program main
  integer :: a, b
  namelist /nml/ a, b

  a = 10
  b = 20
  Write(*,nml)
end program main

dwarfdump of an gfortran emitted binary :
. . .
0x000000b4:     DW_TAG_variable [10]
                  DW_AT_name [DW_FORM_string]   ("a")
                  DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
                  DW_AT_decl_line [DW_FORM_data1]       (20)
                  DW_AT_type [DW_FORM_ref4]     (cu + 0x006d => {0x0000006d}
"integer(kind=4)")
                  DW_AT_declaration [DW_FORM_flag_present]      (true)
                  DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -20)

0x000000c0:     DW_TAG_variable [10]
                  DW_AT_name [DW_FORM_string]   ("b")
                  DW_AT_decl_file [DW_FORM_data1]      
("/home/bhuvan/work/fortran/test/3180/n2.f90")
                  DW_AT_decl_line [DW_FORM_data1]       (20)
                  DW_AT_type [DW_FORM_ref4]     (cu + 0x006d => {0x0000006d}
"integer(kind=4)")
                  DW_AT_declaration [DW_FORM_flag_present]      (true)
                  DW_AT_location [DW_FORM_exprloc]      (DW_OP_fbreg -24)
. . .
0x000000dd:     DW_TAG_namelist [12] *
                  DW_AT_name [DW_FORM_string]   ("nml")

0x000000e2:       DW_TAG_namelist_item [9]
                    DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00b4 =>
{0x000000b4})

0x000000e7:       DW_TAG_namelist_item [9]
                    DW_AT_namelist_item [DW_FORM_ref4]  (cu + 0x00c0 =>
{0x000000c0})

0x000000ec:       NULL

Sample GDB commands output (GDB used here is internal, soon it will be
upstreamed) :

(gdb) ptype nml
type = Type nml
    integer(kind=4) :: a
    integer(kind=4) :: b
End Type nml

(gdb) print nml
$1 = ( a = 10, b = 20 )
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llvm dev - Jul 2021 - [DebugInfo] Fortran namelist support

[llvm-dev] [DebugInfo] Fortran namelist support

[llvm-dev] [DebugInfo] Fortran namelist support

[llvm-dev] [DebugInfo] Fortran namelist support