Introduce gdb-hashtab module in gdbsupport

gdb has some extensions and helpers for working with the libiberty
hash table.  This patch consolidates these and moves them to
gdbsupport.

4 files changed, 106 insertions, 9 deletions

diff --git a/gdbsupport/Makefile.am b/gdbsupport/Makefile.am
index 73d4149f29..9e4334891b 100644
--- a/gdbsupport/Makefile.am
+++ b/gdbsupport/Makefile.am
@@ -52,6 +52,7 @@ libgdbsupport_a_SOURCES = \
     filestuff.cc \
     format.cc \
     gdb-dlfcn.cc \
+    gdb-hashtab.cc \
     gdb_obstack.cc \
     gdb_tilde_expand.cc \
     gdb_wait.cc \
diff --git a/gdbsupport/Makefile.in b/gdbsupport/Makefile.in
index 88d3dd153d..59e1dfedd8 100644
--- a/gdbsupport/Makefile.in
+++ b/gdbsupport/Makefile.in
@@ -151,15 +151,15 @@ am_libgdbsupport_a_OBJECTS = agent.$(OBJEXT) btrace-common.$(OBJEXT) \
 	common-regcache.$(OBJEXT) common-utils.$(OBJEXT) \
 	environ.$(OBJEXT) errors.$(OBJEXT) event-loop.$(OBJEXT) \
 	fileio.$(OBJEXT) filestuff.$(OBJEXT) format.$(OBJEXT) \
-	gdb-dlfcn.$(OBJEXT) gdb_obstack.$(OBJEXT) \
-	gdb_tilde_expand.$(OBJEXT) gdb_wait.$(OBJEXT) \
-	gdb_vecs.$(OBJEXT) job-control.$(OBJEXT) netstuff.$(OBJEXT) \
-	new-op.$(OBJEXT) pathstuff.$(OBJEXT) print-utils.$(OBJEXT) \
-	ptid.$(OBJEXT) rsp-low.$(OBJEXT) run-time-clock.$(OBJEXT) \
-	safe-strerror.$(OBJEXT) scoped_mmap.$(OBJEXT) search.$(OBJEXT) \
-	signals.$(OBJEXT) signals-state-save-restore.$(OBJEXT) \
-	tdesc.$(OBJEXT) thread-pool.$(OBJEXT) xml-utils.$(OBJEXT) \
-	$(am__objects_1)
+	gdb-dlfcn.$(OBJEXT) gdb-hashtab.$(OBJEXT) \
+	gdb_obstack.$(OBJEXT) gdb_tilde_expand.$(OBJEXT) \
+	gdb_wait.$(OBJEXT) gdb_vecs.$(OBJEXT) job-control.$(OBJEXT) \
+	netstuff.$(OBJEXT) new-op.$(OBJEXT) pathstuff.$(OBJEXT) \
+	print-utils.$(OBJEXT) ptid.$(OBJEXT) rsp-low.$(OBJEXT) \
+	run-time-clock.$(OBJEXT) safe-strerror.$(OBJEXT) \
+	scoped_mmap.$(OBJEXT) search.$(OBJEXT) signals.$(OBJEXT) \
+	signals-state-save-restore.$(OBJEXT) tdesc.$(OBJEXT) \
+	thread-pool.$(OBJEXT) xml-utils.$(OBJEXT) $(am__objects_1)
 libgdbsupport_a_OBJECTS = $(am_libgdbsupport_a_OBJECTS)
 AM_V_P = $(am__v_P_@AM_V@)
 am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
@@ -377,6 +377,7 @@ libgdbsupport_a_SOURCES = \
     filestuff.cc \
     format.cc \
     gdb-dlfcn.cc \
+    gdb-hashtab.cc \
     gdb_obstack.cc \
     gdb_tilde_expand.cc \
     gdb_wait.cc \
@@ -483,6 +484,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/filestuff.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/format.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gdb-dlfcn.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gdb-hashtab.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gdb_obstack.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gdb_tilde_expand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gdb_vecs.Po@am__quote@
diff --git a/gdbsupport/gdb-hashtab.cc b/gdbsupport/gdb-hashtab.cc
new file mode 100644
index 0000000000..c42e8fec7b
--- /dev/null
+++ b/gdbsupport/gdb-hashtab.cc
@@ -0,0 +1,44 @@
+/* Hash table wrappers for gdb.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "common-defs.h"
+#include "gdb-hashtab.h"
+
+/* Allocation function for the libiberty hash table which uses an
+   obstack.  The obstack is passed as DATA.  */
+
+void *
+hashtab_obstack_allocate (void *data, size_t size, size_t count)
+{
+  size_t total = size * count;
+  void *ptr = obstack_alloc ((struct obstack *) data, total);
+
+  memset (ptr, 0, total);
+  return ptr;
+}
+
+/* Trivial deallocation function for the libiberty splay tree and hash
+   table - don't deallocate anything.  Rely on later deletion of the
+   obstack.  DATA will be the obstack, although it is not needed
+   here.  */
+
+void
+dummy_obstack_deallocate (void *object, void *data)
+{
+  return;
+}
diff --git a/gdbsupport/gdb-hashtab.h b/gdbsupport/gdb-hashtab.h
new file mode 100644
index 0000000000..65c2dc59a7
--- /dev/null
+++ b/gdbsupport/gdb-hashtab.h
@@ -0,0 +1,50 @@
+/* Hash table wrappers for gdb.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDBSUPPORT_GDB_HASHTAB_H
+#define GDBSUPPORT_GDB_HASHTAB_H
+
+#include "hashtab.h"
+
+/* A deleter for a hash table.  */
+struct htab_deleter
+{
+  void operator() (htab *ptr) const
+  {
+    htab_delete (ptr);
+  }
+};
+
+/* A unique_ptr wrapper for htab_t.  */
+typedef std::unique_ptr<htab, htab_deleter> htab_up;
+
+/* A wrapper for 'delete' that can used as a hash table entry deletion
+   function.  */
+template<typename T>
+void
+htab_delete_entry (void *ptr)
+{
+  delete (T *) ptr;
+}
+
+/* Allocation and deallocation functions for the libiberty hash table
+   which use obstacks.  */
+void *hashtab_obstack_allocate (void *data, size_t size, size_t count);
+void dummy_obstack_deallocate (void *object, void *data);
+
+#endif /* GDBSUPPORT_GDB_HASHTAB_H */