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>

3 files changed, 51 insertions, 42 deletions

diff --git a/gdb/dwarf2/call-site.h b/gdb/dwarf2/call-site.h
index 0a0c7e8..82426c7 100644
--- a/gdb/dwarf2/call-site.h
+++ b/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;
@@ -168,33 +169,16 @@ 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;
-  }
+  /* Return the relocated (using the objfile from PER_OBJFILE) address of the
+     first instruction after this call.  */
 
-  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);
-  }
+  CORE_ADDR pc () const;
 
-  /* Return the address of the first instruction after this call.  */
+  /* Return the unrelocated address of the first instruction after this
+     call.  */
 
-  CORE_ADDR pc () const;
+  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
@@ -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 */
diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
index 23b06dc..737d3ba 100644
--- a/gdb/dwarf2/cu.h
+++ b/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:
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index b20d3cd..4be122f 100644
--- a/gdb/dwarf2/read.c
+++ b/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.  */