From: Tom de Vries <tdevries@suse.de>
To: Tom Tromey <tom@tromey.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH] Start abbrevs at 1 in DWARF assembler
Date: Wed, 6 Dec 2023 15:38:18 +0100 [thread overview]
Message-ID: <68ec55d5-f8a6-4a79-803b-ea05687ad49f@suse.de> (raw)
In-Reply-To: <20231205212306.1438059-1-tom@tromey.com>
On 12/5/23 22:23, Tom Tromey wrote:
> I noticed that the DWARF assembler starts abbrevs at 2.
> I think 1 should be preferred.
Agreed.
How about this approach instead:
...
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index f09da0430ab..0813bbbda09 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -958,13 +958,21 @@ namespace eval Dwarf {
_handle_macro_at_range $attr_value
}
+ # Return the next available abbrev number in the current CU's abbrev
+ # table.
+ proc _get_abbrev_num {} {
+ variable _abbrev_num
+ set res $_abbrev_num
+ incr _abbrev_num
+ return $res
+ }
+
proc _handle_DW_TAG {tag_name {attrs {}} {children {}}} {
variable _abbrev_section
- variable _abbrev_num
variable _constants
set has_children [expr {[string length $children] > 0}]
- set my_abbrev [incr _abbrev_num]
+ set my_abbrev [_get_abbrev_num]
# We somewhat wastefully emit a new abbrev entry for each tag.
# There's no reason for this other than laziness.
...
The nit I see with the patch you propose is that it sets _abbrev_num to
0, and then claims that 0 is the most recently assigned abbrev number,
while it was never assigned.
My feeling is that this solution is more intuitive.
Thanks,
- Tom
> ---
> gdb/testsuite/lib/dwarf.exp | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
> index f09da0430ab..19c89c048fe 100644
> --- a/gdb/testsuite/lib/dwarf.exp
> +++ b/gdb/testsuite/lib/dwarf.exp
> @@ -564,8 +564,8 @@ namespace eval Dwarf {
> # for Fission.
> variable _abbrev_section
>
> - # The next available abbrev number in the current CU's abbrev
> - # table.
> + # The most recently assigned abbrev number in the current CU's
> + # abbrev table.
> variable _abbrev_num
>
> # The string table for this assembly. The key is the string; the
> @@ -1485,7 +1485,7 @@ namespace eval Dwarf {
>
> set cu_num [incr _cu_count]
> set my_abbrevs [_compute_label "abbrev${cu_num}_begin"]
> - set _abbrev_num 1
> + set _abbrev_num 0
>
> set _cu_label [_compute_label "cu${cu_num}_begin"]
> set start_label [_compute_label "cu${cu_num}_start"]
> @@ -1597,7 +1597,7 @@ namespace eval Dwarf {
>
> set cu_num [incr _cu_count]
> set my_abbrevs [_compute_label "abbrev${cu_num}_begin"]
> - set _abbrev_num 1
> + set _abbrev_num 0
>
> set _cu_label [_compute_label "cu${cu_num}_begin"]
> set start_label [_compute_label "cu${cu_num}_start"]
next prev parent reply other threads:[~2023-12-06 14:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 21:23 Tom Tromey
2023-12-06 14:38 ` Tom de Vries [this message]
2023-12-06 15:41 ` Tom Tromey
2023-12-06 16:27 ` Tom de Vries
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