[PATCH] gdb/dwarf: add dwarf2_cu::find_die method

[PATCH] gdb/dwarf: add dwarf2_cu::find_die method

[simon.marchi]

From: Simon Marchi <simon.marchi@efficios.com>

I added this small helper method in the series I'm writing, to make
finding a DIE by section offset a bit nicer than using the unordered_set
methods.  It doesn't have any dependencies, so I thought I would submit
it on its own.

Change-Id: If7313194ab09d9bd6d6a52c24eb6fd9a9c1b76e0
---
 gdb/dwarf2/cu.h   | 9 +++++++++
 gdb/dwarf2/read.c | 9 ++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
index 5683291fbcfe..6eda19b80a61 100644
--- a/gdb/dwarf2/cu.h
+++ b/gdb/dwarf2/cu.h
@@ -99,6 +99,15 @@ struct dwarf2_cu
   void add_dependence (dwarf2_per_cu *ref_per_cu)
   { m_dependencies.emplace (ref_per_cu); }
 
+  /* Find the DIE at section offset SECT_OFF.
+
+     Return nullptr if not found.  */
+  die_info *find_die (sect_offset sect_off) const
+  {
+    auto it = die_hash.find (sect_off);
+    return it != die_hash.end () ? *it : nullptr;
+  }
+
   /* The header of the compilation unit.  */
   struct comp_unit_head header;
 
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 2523ca869598..6b7f2c784768 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -18260,8 +18260,7 @@ follow_die_offset (sect_offset sect_off, int offset_in_dwz,
 
   *ref_cu = target_cu;
 
-  auto it = target_cu->die_hash.find (sect_off);
-  return it != target_cu->die_hash.end () ? *it : nullptr;
+  return target_cu->find_die (sect_off);
 }
 
 /* Follow reference attribute ATTR of SRC_DIE.
@@ -18629,8 +18628,8 @@ follow_die_sig_1 (struct die_info *src_die, struct signatured_type *sig_type,
   gdb_assert (sig_cu != NULL);
   gdb_assert (to_underlying (sig_type->type_offset_in_section) != 0);
 
-  if (auto die_it = sig_cu->die_hash.find (sig_type->type_offset_in_section);
-      die_it != sig_cu->die_hash.end ())
+  if (die_info *die = sig_cu->find_die (sig_type->type_offset_in_section);
+      die != nullptr)
     {
       /* For .gdb_index version 7 keep track of included TUs.
 	 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.  */
@@ -18639,7 +18638,7 @@ follow_die_sig_1 (struct die_info *src_die, struct signatured_type *sig_type,
 	(*ref_cu)->per_cu->imported_symtabs.push_back (sig_cu->per_cu);
 
       *ref_cu = sig_cu;
-      return *die_it;
+      return die;
     }
 
   return NULL;

base-commit: 876c853cb99cd9c097fa915c8d00bf6b9d7c5904
-- 
2.49.0

Re: [PATCH] gdb/dwarf: add dwarf2_cu::find_die method

[Kevin Buettner]

On Thu, 24 Apr 2025 16:36:02 -0400
simon.marchi@polymtl.ca wrote:

> I added this small helper method in the series I'm writing, to make
> finding a DIE by section offset a bit nicer than using the unordered_set
> methods.  It doesn't have any dependencies, so I thought I would submit
> it on its own.

LGTM.

Approved-by: Kevin Buettner <kevinb@redhat.com>

Re: [PATCH] gdb/dwarf: add dwarf2_cu::find_die method

[Simon Marchi]

On 2025-04-24 17:42, Kevin Buettner wrote:
> On Thu, 24 Apr 2025 16:36:02 -0400
> simon.marchi@polymtl.ca wrote:
> 
>> I added this small helper method in the series I'm writing, to make
>> finding a DIE by section offset a bit nicer than using the unordered_set
>> methods.  It doesn't have any dependencies, so I thought I would submit
>> it on its own.
> 
> LGTM.
> 
> Approved-by: Kevin Buettner <kevinb@redhat.com>
> 

Thanks, pushed.

Simon