[PATCH 4/8] gdb/dwarf: add dwo_file::find_tus

[simon.marchi@polymtl.ca]

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

Add this little helper to make finding a TU a bit simpler.  I always
find the STL way of doing things cryptic, so I think that hiding it in
small helper methods makes the code clearer.

A subsequent patch will add more uses of it

Change-Id: Ibfb20d0e44c65d2ff729f3e0980ec4435f223aef
---
 gdb/dwarf2/read.c | 18 ++++++++++++++----
 gdb/dwarf2/read.h |  5 +++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 3a0602b4ac08..fd1c37ad8e89 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -266,6 +266,18 @@ struct loclists_rnglists_header
   unsigned int offset_entry_count;
 };
 
+/* See read.h.  */
+
+dwo_unit *
+dwo_file::find_tu (ULONGEST signature) const
+{
+  auto it = this->tus.find (signature);
+  if (it == this->tus.end ())
+    return nullptr;
+
+  return it->get ();
+}
+
 /* include/dwarf2.h defines the DWP section codes.
    It defines a max value but it doesn't define a min value, which we
    use for error checking, so provide one.  */
@@ -2342,12 +2354,10 @@ lookup_dwo_signatured_type (struct dwarf2_cu *cu, ULONGEST sig)
   /* Note: cu->dwo_unit is the dwo_unit that references this TU, not the
      dwo_unit of the TU itself.  */
   dwo_file *dwo_file = cu->dwo_unit->dwo_file;
-  auto it = dwo_file->tus.find (sig);
-  if (it == dwo_file->tus.end ())
+  dwo_unit *dwo_entry = dwo_file->find_tu (sig);
+  if (dwo_entry == nullptr)
     return nullptr;
 
-  dwo_unit *dwo_entry = it->get ();
-
   /* If the global table doesn't have an entry for this TU, add one.  */
   if (sig_type_it == per_bfd->signatured_types.end ())
     {
diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
index 5a46786e4f3f..5c61e91870b4 100644
--- a/gdb/dwarf2/read.h
+++ b/gdb/dwarf2/read.h
@@ -585,6 +585,11 @@ struct dwo_file
   dwo_file () = default;
   DISABLE_COPY_AND_ASSIGN (dwo_file);
 
+  /* Look for a type unit with signature SIGNATURE in this dwo_file.
+
+     Return nullptr if not found.  */
+  dwo_unit *find_tu (ULONGEST signature) const;
+
   /* The DW_AT_GNU_dwo_name or DW_AT_dwo_name attribute.
      For virtual DWO files the name is constructed from the section offsets
      of abbrev,line,loc,str_offsets so that we combine virtual DWO files
-- 
2.53.0