gdb: remove unnecessary NULL checks before xfree

I was inspired by a series of patches merged by Alan Modra in the other
projects, so I did the same in GDB with a bit of Coccinelle and grep.

This patch removes the unnecessary NULL checks before calls to xfree.
They are unnecessary because xfree already does a NULL check.  Since
free is supposed to handle NULL values correctly, the NULL check in
xfree itself is also questionable, but I've left it there for now.

gdb/ChangeLog:

	* coffread.c (patch_type): Remove NULL check before xfree.
	* corefile.c (set_gnutarget): Likewise.
	* cp-abi.c (set_cp_abi_as_auto_default): Likewise.
	* exec.c (build_section_table): Likewise.
	* remote.c (remote_target::pass_signals): Likewise.
	* utils.c (n_spaces): Likewise.
	* cli/cli-script.c (document_command): Likewise.
	* i386-windows-tdep.c (core_process_module_section): Likewise.
	* linux-fork.c (struct fork_info) <~fork_info>: Likewise.

gdb/ChangeLog

@@ -1,3 +1,15 @@
+2020-05-21  Simon Marchi  <simon.marchi@efficios.com>
+
+	* coffread.c (patch_type): Remove NULL check before xfree.
+	* corefile.c (set_gnutarget): Likewise.
+	* cp-abi.c (set_cp_abi_as_auto_default): Likewise.
+	* exec.c (build_section_table): Likewise.
+	* remote.c (remote_target::pass_signals): Likewise.
+	* utils.c (n_spaces): Likewise.
+	* cli/cli-script.c (document_command): Likewise.
+	* i386-windows-tdep.c (core_process_module_section): Likewise.
+	* linux-fork.c (struct fork_info) <~fork_info>: Likewise.
+
 2020-05-20  Simon Marchi  <simon.marchi@efficios.com>
 
 	* symfile.c (reread_symbols): Clear objfile's section_offsets

gdb/cli/cli-script.c

@@ -1528,8 +1528,7 @@ document_command (const char *comname, int from_tty)
   counted_command_line doclines = read_command_lines (prompt.c_str (),
 						      from_tty, 0, 0);
 
-  if (c->doc)
+  xfree ((char *) c->doc);
-    xfree ((char *) c->doc);
 
   {
     struct command_line *cl1;

gdb/coffread.c

@@ -1467,8 +1467,7 @@ patch_type (struct type *type, struct type *real_type)
     {
       /* The previous copy of TYPE_NAME is allocated by
 	 process_coff_symbol.  */
-      if (target->name ())
+      xfree ((char *) target->name ());
-	xfree ((char*) target->name ());
       target->set_name (xstrdup (real_target->name ()));
     }
 }

gdb/corefile.c

@@ -472,8 +472,7 @@ complete_set_gnutarget (struct cmd_list_element *cmd,
 void
 set_gnutarget (const char *newtarget)
 {
-  if (gnutarget_string != NULL)
+  xfree (gnutarget_string);
-    xfree (gnutarget_string);
   gnutarget_string = xstrdup (newtarget);
   set_gnutarget_command (NULL, 0, NULL);
 }

gdb/cp-abi.c

@@ -273,10 +273,8 @@ set_cp_abi_as_auto_default (const char *short_name)
 		    _("Cannot find C++ ABI \"%s\" to set it as auto default."),
 		    short_name);
 
-  if (auto_cp_abi.longname != NULL)
+  xfree ((char *) auto_cp_abi.longname);
-    xfree ((char *) auto_cp_abi.longname);
+  xfree ((char *) auto_cp_abi.doc);
-  if (auto_cp_abi.doc != NULL)
-    xfree ((char *) auto_cp_abi.doc);
 
   auto_cp_abi = *abi;
 

gdb/exec.c

@@ -648,8 +648,7 @@ build_section_table (struct bfd *some_bfd, struct target_section **start,
   unsigned count;
 
   count = bfd_count_sections (some_bfd);
-  if (*start)
+  xfree (*start);
-    xfree (* start);
   *start = XNEWVEC (struct target_section, count);
   *end = *start;
   bfd_map_over_sections (some_bfd, add_to_section_table, (char *) end);

gdb/i386-windows-tdep.c

@@ -142,8 +142,7 @@ core_process_module_section (bfd *abfd, asection *sect, void *obj)
   data->module_count++;
 
 out:
-  if (buf)
+  xfree (buf);
-    xfree (buf);
   return;
 }
 

gdb/linux-fork.c

@@ -61,8 +61,8 @@ struct fork_info
 
     if (savedregs)
       delete savedregs;
-    if (filepos)
+
-      xfree (filepos);
+    xfree (filepos);
   }
 
   ptid_t ptid = null_ptid;

gdb/remote.c

@@ -2615,8 +2615,7 @@ remote_target::pass_signals (gdb::array_view<const unsigned char> pass_signals)
 	  putpkt (pass_packet);
 	  getpkt (&rs->buf, 0);
 	  packet_ok (rs->buf, &remote_protocol_packets[PACKET_QPassSignals]);
-	  if (rs->last_pass_packet)
+	  xfree (rs->last_pass_packet);
-	    xfree (rs->last_pass_packet);
 	  rs->last_pass_packet = pass_packet;
 	}
       else

gdb/symfile.c

@@ -3404,8 +3404,7 @@ enum ovly_index
 static void
 simple_free_overlay_table (void)
 {
-  if (cache_ovly_table)
+  xfree (cache_ovly_table);
-    xfree (cache_ovly_table);
   cache_novlys = 0;
   cache_ovly_table = NULL;
   cache_ovly_table_base = 0;

gdb/utils.c

@@ -2260,8 +2260,7 @@ n_spaces (int n)
 
   if (n > max_spaces)
     {
-      if (spaces)
+      xfree (spaces);
-	xfree (spaces);
       spaces = (char *) xmalloc (n + 1);
       for (t = spaces + n; t != spaces;)
 	*--t = ' ';