From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Thu, 24 Apr 2025 20:01:46 +0000 (-0400)
Subject: gdb/dwarf: avoid cutu_reader moves
X-Git-Tag: binutils-2_45~743
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=605b4e6f36615974635a17eed999c8ee34821e92;p=thirdparty%2Fbinutils-gdb.git

gdb/dwarf: avoid cutu_reader moves

In process_psymtab_comp_unit and ensure_cu_exists, we create a temporary
cutu_reader on the stack, then move it to a heap allocated cutu_reader
once we confirmed the unit is not dummy.  I think it's unnecessary to
create a temporary cutu_reader.  The only downside of not doing so is that if it
ends up that the CU is dummy, we made an allocation/deallocation for
nothing.  Dummy CUs are a rare thing, it shouldn't change anything.

This allows removing the cutu_reader move constructor.

Change-Id: I44742d471c495055ee46db41c0e7bdfbd2d5c0b7
Approved-By: Tom Tromey <tom@tromey.com>
---

diff --git a/gdb/dwarf2/cooked-indexer.c b/gdb/dwarf2/cooked-indexer.c
index 89cbdc6e975..5776dc5e956 100644
--- a/gdb/dwarf2/cooked-indexer.c
+++ b/gdb/dwarf2/cooked-indexer.c
@@ -109,16 +109,18 @@ cooked_indexer::ensure_cu_exists (cutu_reader *reader,
   cutu_reader *result = m_index_storage->get_reader (per_cu);
   if (result == nullptr)
     {
-      cutu_reader new_reader (*per_cu, *per_objfile, nullptr, nullptr, false,
-			      language_minimal,
-			      &m_index_storage->get_abbrev_table_cache ());
-
-      if (new_reader.is_dummy () || new_reader.top_level_die () == nullptr
-	  || !new_reader.top_level_die ()->has_children)
+      const abbrev_table_cache &abbrev_table_cache
+	= m_index_storage->get_abbrev_table_cache ();
+      auto new_reader
+	= std::make_unique<cutu_reader> (*per_cu, *per_objfile, nullptr,
+					 nullptr, false, language_minimal,
+					 &abbrev_table_cache);
+
+      if (new_reader->is_dummy () || new_reader->top_level_die () == nullptr
+	  || !new_reader->top_level_die ()->has_children)
 	return nullptr;
 
-      auto copy = std::make_unique<cutu_reader> (std::move (new_reader));
-      result = m_index_storage->preserve (std::move (copy));
+      result = m_index_storage->preserve (std::move (new_reader));
     }
 
   if (result->is_dummy () || result->top_level_die () == nullptr
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index e9cc542f8c9..aa830d402c4 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -3196,15 +3196,17 @@ process_psymtab_comp_unit (dwarf2_per_cu *this_cu,
   cutu_reader *reader = storage->get_reader (this_cu);
   if (reader == nullptr)
     {
-      cutu_reader new_reader (*this_cu, *per_objfile, nullptr, nullptr, false,
-			      language_minimal,
-			      &storage->get_abbrev_table_cache ());
-
-      if (new_reader.cu () == nullptr || new_reader.is_dummy ())
+      const abbrev_table_cache &abbrev_table_cache
+	= storage->get_abbrev_table_cache ();
+      auto new_reader = std::make_unique<cutu_reader> (*this_cu, *per_objfile,
+						       nullptr, nullptr, false,
+						       language_minimal,
+						       &abbrev_table_cache);
+
+      if (new_reader->cu () == nullptr || new_reader->is_dummy ())
 	return;
 
-      auto copy = std::make_unique<cutu_reader> (std::move (new_reader));
-      reader = storage->preserve (std::move (copy));
+      reader = storage->preserve (std::move (new_reader));
     }
 
   if (reader->top_level_die () == nullptr || reader->is_dummy ())
diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
index c69d8fbe5f1..5b4c8f673a0 100644
--- a/gdb/dwarf2/read.h
+++ b/gdb/dwarf2/read.h
@@ -934,8 +934,6 @@ public:
 
   DISABLE_COPY_AND_ASSIGN (cutu_reader);
 
-  cutu_reader (cutu_reader &&) = default;
-
   /* Return true if either:
 
       - the unit is empty (just a header without any DIE)