[PATCH] Allow reference form for DW_AT_associated and DW_AT_allocated attributes

[Sharma, Alok Kumar]

Thanks for your comment/suggestion. Please find updated patch as an attachment.

gdb/ChangeLog

       * dwarf2/read.c (set_die_type): Removed conditions to restrict
       forms for DW_AT_associated and DW_AT_allocated attributes,
       which is already checked in function attr_to_dynamic_prop.

Regards,
Alok

-----Original Message-----
From: Andrew Burgess <andrew.burgess@embecosm.com> 
Sent: Wednesday, July 1, 2020 1:50 PM
To: Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>
Cc: gdb-patches@sourceware.org; George, Jini Susan <JiniSusan.George@amd.com>; Achra, Nitika <Nitika.Achra@amd.com>
Subject: Re: [PATCH] Allow reference form for DW_AT_associated and DW_AT_allocated attributes

[CAUTION: External Email]

* Sharma, Alok Kumar <AlokKumar.Sharma@amd.com> [2020-07-01 07:01:53 +0000]:

> Hi All,
>
> I request you all to please review this patch. Below are the details.
>
> Problem Description:
>     Currently, GDB rejects the (die) reference form while it accepts exprloc
>     form. It is allowed in DWARF standard. "Table 7.5: Attribute encodings"
>     in DWARF5 standard. Flang compiler assigns (die) reference to
>     DW_AT_associated and DW_AT_allocated for some cases.
> Resolution:
>     Now ' set_die_type' Is modified to accept reference form as well.
> This change will not impact testsuite for gfortran, and will fix 
> failures for Flang compiler with existing testsuite.
>
>     gdb/ChangeLog
>
>             * dwarf2/read.c (set_die_type): Allow reference form for
>             DW_AT_associated and DW_AT_allocated attributes.
>
> Please let me know your valuable comments.
>
> Regards,
> Alok
>
> From 9a37e9973e513738234b4fed4b66d0ffc1438398 Mon Sep 17 00:00:00 2001
> From: alosharm <AlokKumar.Sharma@amd.com>
> Date: Wed, 1 Jul 2020 11:53:09 +0530
> Subject: [PATCH] Allow reference form for DW_AT_associated and 
> DW_AT_allocated  attributes
>
> Currently, GDB rejects the (die) reference form while it accepts 
> exprloc form. It is allowed in DWARF standard. "Table 7.5: Attribute encodings"
> in DWARF5 standard. Flang compiler assigns (die) reference to 
> DW_AT_associated and DW_AT_allocated for some cases.
>
> gdb/ChangeLog
>
>       * dwarf2/read.c (set_die_type): Allow reference form for
>       DW_AT_associated and DW_AT_allocated attributes.
> ---
>  gdb/ChangeLog     | 5 +++++
>  gdb/dwarf2/read.c | 4 ++--
>  2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 
> d64f572e07..75ea79471c 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,8 @@
> +2020-07-01  Alok Kumar Sharma  <AlokKumar.Sharma@amd.com>
> +
> +     * dwarf2/read.c (set_die_type): Allow reference form for
> +     DW_AT_associated and DW_AT_allocated attributes.
> +
>  2020-06-30  Tom Tromey  <tromey@adacore.com>
>
>       * dwarf2/read.c (quirk_rust_enum): Correctly call diff --git 
> a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index b097f624b6..0fba590184 
> 100644
> --- a/gdb/dwarf2/read.c
> +++ b/gdb/dwarf2/read.c
> @@ -23859,7 +23859,7 @@ set_die_type (struct die_info *die, struct 
> type *type, struct dwarf2_cu *cu)
>
>    /* Read DW_AT_allocated and set in type.  */
>    attr = dwarf2_attr (die, DW_AT_allocated, cu);
> -  if (attr != NULL && attr->form_is_block ())
> +  if (attr != NULL && (attr->form_is_block () || attr->form_is_ref 
> + ()))
>      {
>        struct type *prop_type = cu->addr_sized_int_type (false);
>        if (attr_to_dynamic_prop (attr, die, cu, &prop, prop_type))

Looking at attr_to_dynamic_prop we handle block, ref, and constants, otherwise we give complain about an unexpected attribute type.

I think then that there's no need to check the form of the attribute here at all, you could just perform a NULL check and proceed to handle the attribute.  The error in the else block (about incorrect attribute
form) can be deleted.

This applies to both the changes in this patch.

Thanks,
Andrew


> @@ -23874,7 +23874,7 @@ set_die_type (struct die_info *die, struct 
> type *type, struct dwarf2_cu *cu)
>
>    /* Read DW_AT_associated and set in type.  */
>    attr = dwarf2_attr (die, DW_AT_associated, cu);
> -  if (attr != NULL && attr->form_is_block ())
> +  if (attr != NULL && (attr->form_is_block () || attr->form_is_ref 
> + ()))
>      {
>        struct type *prop_type = cu->addr_sized_int_type (false);
>        if (attr_to_dynamic_prop (attr, die, cu, &prop, prop_type))
> --
> 2.17.1

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