Convert dwarf2_cu::call_site_htab to new hash table

Convert one use of htab_t, mapping (unrelocated) pc to call_site
objects, to `gdb::unordered_map<unrelocated_addr, call_site *>`.

Change-Id: I40a0903253a8589dbdcb75d52ad4d233931f6641
Approved-By: Tom Tromey <tom@tromey.com>

gdb/dwarf2/call-site.h

@@ -25,6 +25,7 @@
 #include "dwarf2/types.h"
 #include "../frame.h"
 #include "gdbsupport/function-view.h"
+#include "gdbsupport/unordered_set.h"
 
 struct dwarf2_locexpr_baton;
 struct dwarf2_per_cu_data;
@@ -168,34 +169,17 @@ struct call_site
     : per_cu (per_cu), per_objfile (per_objfile), m_unrelocated_pc (pc)
   {}
 
-  static int
-  eq (const call_site *a, const call_site *b)
-  {
-    return a->m_unrelocated_pc == b->m_unrelocated_pc;
-  }
-
-  static hashval_t
-  hash (const call_site *a)
-  {
-    return (hashval_t) a->m_unrelocated_pc;
-  }
-
-  static int
-  eq (const void *a, const void *b)
-  {
-    return eq ((const call_site *)a, (const call_site *)b);
-  }
-
-  static hashval_t
-  hash (const void *a)
-  {
-    return hash ((const call_site *)a);
-  }
-
-  /* Return the address of the first instruction after this call.  */
+  /* Return the relocated (using the objfile from PER_OBJFILE) address of the
+     first instruction after this call.  */
 
   CORE_ADDR pc () const;
 
+  /* Return the unrelocated address of the first instruction after this
+     call.  */
+
+  unrelocated_addr unrelocated_pc () const noexcept
+  { return m_unrelocated_pc; }
+
   /* Call CALLBACK for each target address.  CALLER_FRAME (for
      registers) can be NULL if it is not known.  This function may
      throw NO_ENTRY_VALUE_ERROR.  */
@@ -241,4 +225,37 @@ public:
   struct call_site_parameter parameter[];
 };
 
+/* Key hash type to store call_site objects in gdb::unordered_set, identified by
+   their unrelocated PC.  */
+
+struct call_site_hash_pc
+{
+  using is_transparent = void;
+
+  std::size_t operator() (const call_site *site) const noexcept
+  { return (*this) (site->unrelocated_pc ()); }
+
+  std::size_t operator() (unrelocated_addr pc) const noexcept
+  { return std::hash<unrelocated_addr> () (pc); }
+};
+
+/* Key equal type to store call_site objects in gdb::unordered_set, identified
+   by their unrelocated PC.  */
+
+struct call_site_eq_pc
+{
+  using is_transparent = void;
+
+  bool operator() (const call_site *a, const call_site *b) const noexcept
+  { return (*this) (a->unrelocated_pc (), b); }
+
+  bool operator() (unrelocated_addr pc, const call_site *site) const noexcept
+  { return pc == site->unrelocated_pc (); }
+};
+
+/* Set of call_site objects identified by their unrelocated PC.  */
+
+using call_site_htab_t
+  = gdb::unordered_set<call_site *, call_site_hash_pc, call_site_eq_pc>;
+
 #endif /* CALL_SITE_H */

gdb/dwarf2/cu.h

@@ -175,7 +175,7 @@ public:
   std::vector<delayed_method_info> method_list;
 
   /* To be copied to symtab->call_site_htab.  */
-  htab_up call_site_htab;
+  call_site_htab_t call_site_htab;
 
   /* Non-NULL if this CU came from a DWO file.
      There is an invariant here that is important to remember:

gdb/dwarf2/read.c

@@ -10289,7 +10289,6 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
   struct objfile *objfile = per_objfile->objfile;
   struct gdbarch *gdbarch = objfile->arch ();
   struct attribute *attr;
-  void **slot;
   int nparams;
   struct die_info *child_die;
 
@@ -10309,21 +10308,6 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
     }
   unrelocated_addr pc = attr->as_address ();
 
-  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.get (), &call_site_local, INSERT);
-  if (*slot != NULL)
-    {
-      complaint (_("Duplicate PC %s for DW_TAG_call_site "
-		   "DIE %s [in module %s]"),
-		 paddress (gdbarch, (CORE_ADDR) pc), sect_offset_str (die->sect_off),
-		 objfile_name (objfile));
-      return;
-    }
-
   /* Count parameters at the caller.  */
 
   nparams = 0;
@@ -10348,7 +10332,15 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
 		      struct call_site,
 		      sizeof (*call_site) + sizeof (call_site->parameter[0]) * nparams))
     struct call_site (pc, cu->per_cu, per_objfile);
-  *slot = call_site;
+  
+  if (!cu->call_site_htab.emplace (call_site).second)
+    {
+      complaint (_("Duplicate PC %s for DW_TAG_call_site "
+		   "DIE %s [in module %s]"),
+		 paddress (gdbarch, (CORE_ADDR) pc), sect_offset_str (die->sect_off),
+		 objfile_name (objfile));
+      return;
+    }
 
   /* We never call the destructor of call_site, so we must ensure it is
      trivially destructible.  */

gdb/symtab.c

@@ -396,42 +396,35 @@ linetable_entry::pc (const struct objfile *objfile) const
 call_site *
 compunit_symtab::find_call_site (CORE_ADDR pc) const
 {
-  if (m_call_site_htab == nullptr)
-    return nullptr;
-
   CORE_ADDR delta = this->objfile ()->text_section_offset ();
-  unrelocated_addr unrelocated_pc = (unrelocated_addr) (pc - delta);
 
-  struct call_site call_site_local (unrelocated_pc, nullptr, nullptr);
-  void **slot
-    = htab_find_slot (m_call_site_htab, &call_site_local, NO_INSERT);
-  if (slot != nullptr)
-    return (call_site *) *slot;
+  if (auto it = m_call_site_htab->find (static_cast<unrelocated_addr> (pc - delta));
+      it != m_call_site_htab->end ())
+    return *it;
 
   /* See if the arch knows another PC we should try.  On some
      platforms, GCC emits a DWARF call site that is offset from the
      actual return location.  */
   struct gdbarch *arch = objfile ()->arch ();
   CORE_ADDR new_pc = gdbarch_update_call_site_pc (arch, pc);
+
   if (pc == new_pc)
     return nullptr;
 
-  unrelocated_pc = (unrelocated_addr) (new_pc - delta);
-  call_site new_call_site_local (unrelocated_pc, nullptr, nullptr);
-  slot = htab_find_slot (m_call_site_htab, &new_call_site_local, NO_INSERT);
-  if (slot == nullptr)
-    return nullptr;
+  if (auto it = m_call_site_htab->find (static_cast<unrelocated_addr> (new_pc - delta));
+      it != m_call_site_htab->end ())
+    return *it;
 
-  return (call_site *) *slot;
+  return nullptr;
 }
 
 /* See symtab.h.  */
 
 void
-compunit_symtab::set_call_site_htab (htab_up call_site_htab)
+compunit_symtab::set_call_site_htab (call_site_htab_t &&call_site_htab)
 {
   gdb_assert (m_call_site_htab == nullptr);
-  m_call_site_htab = call_site_htab.release ();
+  m_call_site_htab = new call_site_htab_t (std::move (call_site_htab));
 }
 
 /* See symtab.h.  */
@@ -500,8 +493,7 @@ void
 compunit_symtab::finalize ()
 {
   this->forget_cached_source_info ();
-  if (m_call_site_htab != nullptr)
-    htab_delete (m_call_site_htab);
+  delete m_call_site_htab;
 }
 
 /* The relocated address of the minimal symbol, using the section

gdb/symtab.h

@@ -24,6 +24,7 @@
 #include <vector>
 #include <string>
 #include <set>
+#include "dwarf2/call-site.h"
 #include "gdbsupport/gdb_vecs.h"
 #include "gdbtypes.h"
 #include "gdbsupport/gdb_obstack.h"
@@ -1947,7 +1948,7 @@ struct compunit_symtab
   symtab *primary_filetab () const;
 
   /* Set m_call_site_htab.  */
-  void set_call_site_htab (htab_up call_site_htab);
+  void set_call_site_htab (call_site_htab_t &&call_site_htab);
 
   /* Find call_site info for PC.  */
   call_site *find_call_site (CORE_ADDR pc) const;
@@ -2014,7 +2015,7 @@ struct compunit_symtab
   unsigned int m_epilogue_unwind_valid : 1;
 
   /* struct call_site entries for this compilation unit or NULL.  */
-  htab_t m_call_site_htab;
+  call_site_htab_t *m_call_site_htab;
 
   /* The macro table for this symtab.  Like the blockvector, this
      is shared between different symtabs in a given compilation unit.