[binutils-gdb] Don't obstack-allocate the call site hash table

[binutils-gdb] Don't obstack-allocate the call site hash table

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4122e647d571b35b4aba73ec481bc2d72d193e54

commit 4122e647d571b35b4aba73ec481bc2d72d193e54
Author: Tom Tromey <tromey@adacore.com>
Date:   Wed Jun 5 09:38:53 2024 -0600

    Don't obstack-allocate the call site hash table
    
    The call site hash table is the last hash table using obstack
    allocation.  In one large (non-public) test case, these hash tables
    take a substiantial amount of memory.  Some of this memory is wasted
    -- whenever the hash table is resized, the old table is not freed.
    
    This patch fixes the problem by changing this hash table to be
    heap-allocated.  This means that resizing will no longer "leak"
    memory.

Diff:
---
 gdb/dwarf2/cu.h   |  2 +-
 gdb/dwarf2/read.c | 13 ++++++-------
 gdb/objfiles.c    |  2 ++
 gdb/symtab.c      | 14 ++++++++++++--
 gdb/symtab.h      |  8 +++++++-
 5 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
index d23cc9b70e5..b0ec2d6fabc 100644
--- a/gdb/dwarf2/cu.h
+++ b/gdb/dwarf2/cu.h
@@ -170,7 +170,7 @@ struct dwarf2_cu
   std::vector<delayed_method_info> method_list;
 
   /* To be copied to symtab->call_site_htab.  */
-  htab_t call_site_htab = nullptr;
+  htab_up call_site_htab;
 
   /* Non-NULL if this CU came from a DWO file.
      There is an invariant here that is important to remember:
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index eee8b454e5f..01d1a6bcb3a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -6233,7 +6233,7 @@ process_full_comp_unit (dwarf2_cu *cu, enum language pretend_language)
       else
 	cust->set_epilogue_unwind_valid (true);
 
-      cust->set_call_site_htab (cu->call_site_htab);
+      cust->set_call_site_htab (std::move (cu->call_site_htab));
     }
 
   per_objfile->set_symtab (cu->per_cu, cust);
@@ -10208,13 +10208,12 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
     }
   unrelocated_addr pc = attr->as_address ();
 
-  if (cu->call_site_htab == NULL)
-    cu->call_site_htab = htab_create_alloc_ex (16, call_site::hash,
-					       call_site::eq, NULL,
-					       &objfile->objfile_obstack,
-					       hashtab_obstack_allocate, NULL);
+  if (cu->call_site_htab == nullptr)
+    cu->call_site_htab.reset (htab_create_alloc (16, call_site::hash,
+						 call_site::eq, nullptr,
+						 xcalloc, xfree));
   struct call_site call_site_local (pc, nullptr, nullptr);
-  slot = htab_find_slot (cu->call_site_htab, &call_site_local, INSERT);
+  slot = htab_find_slot (cu->call_site_htab.get (), &call_site_local, INSERT);
   if (*slot != NULL)
     {
       complaint (_("Duplicate PC %s for DW_TAG_call_site "
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index e6b0ca7f29b..368e129b49d 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -530,6 +530,8 @@ objfile::~objfile ()
   /* It still may reference data modules have associated with the objfile and
      the symbol file data.  */
   forget_cached_source_info ();
+  for (compunit_symtab *cu : compunits ())
+    cu->finalize ();
 
   breakpoint_free_objfile (this);
   btrace_free_objfile (this);
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 39a6915ee76..41d71beec2a 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -428,10 +428,10 @@ compunit_symtab::find_call_site (CORE_ADDR pc) const
 /* See symtab.h.  */
 
 void
-compunit_symtab::set_call_site_htab (htab_t call_site_htab)
+compunit_symtab::set_call_site_htab (htab_up call_site_htab)
 {
   gdb_assert (m_call_site_htab == nullptr);
-  m_call_site_htab = call_site_htab;
+  m_call_site_htab = call_site_htab.release ();
 }
 
 /* See symtab.h.  */
@@ -494,6 +494,16 @@ compunit_symtab::forget_cached_source_info ()
     s->release_fullname ();
 }
 
+/* See symtab.h.  */
+
+void
+compunit_symtab::finalize ()
+{
+  this->forget_cached_source_info ();
+  if (m_call_site_htab != nullptr)
+    htab_delete (m_call_site_htab);
+}
+
 /* The relocated address of the minimal symbol, using the section
    offsets from OBJFILE.  */
 
diff --git a/gdb/symtab.h b/gdb/symtab.h
index d0b599fc58e..a5631a27b5e 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -1957,7 +1957,7 @@ struct compunit_symtab
   symtab *primary_filetab () const;
 
   /* Set m_call_site_htab.  */
-  void set_call_site_htab (htab_t call_site_htab);
+  void set_call_site_htab (htab_up call_site_htab);
 
   /* Find call_site info for PC.  */
   call_site *find_call_site (CORE_ADDR pc) const;
@@ -1968,6 +1968,12 @@ struct compunit_symtab
   /* Clear any cached source file names.  */
   void forget_cached_source_info ();
 
+  /* This is called when an objfile is being destroyed and will free
+     any resources used by this compunit_symtab.  Normally a
+     destructor would be used instead, but at the moment
+     compunit_symtab objects are allocated on an obstack.  */
+  void finalize ();
+
   /* Unordered chain of all compunit symtabs of this objfile.  */
   struct compunit_symtab *next;