target_stack -> current_top_target() throughout

The recent C++ification of target_ops replaced references to the old
"current_target" squashed target throughout with references to a
"target_stack" pointer.  I had picked the "target_stack" name very
early in the multi-target work, and managed to stick with it, even
though it's a bit of a misnomer, since it isn't really a "target
stack" object, but a pointer into the current top target in the stack.
As I'm splitting more pieces off of the multi-target branch, I've come
to think that it's better to rename it now.  A following patch will
introduce a new class to represent a target stack, and "target_stack"
would be _its_ ideal name.  (In the branch, the class is called
a_target_stack to work around the clash.)

Thus this commit renames target_stack to current_top_target and
replaces all references throughout.  Also, while at it,
current_top_target is made a function instead of a pointer, to make it
possible to change its internal implementation without leaking
implementation details out.  In a couple patches, the implementation
of the function will change to refer to a target stack object, and
then further down the multi-target work, it'll change again to find
the right target stack for the current inferior.

gdb/ChangeLog:
2018-06-07  Pedro Alves  <palves@redhat.com>

	* target.h (target_stack): Delete.
	(current_top_target): Declare function.
	* target.c (target_stack): Delete.
	(g_current_top_target): New.
	(current_top_target): New function.
	* auxv.c: Use current_top_target instead of target_stack
	throughout.
	* avr-tdep.c: Likewise.
	* breakpoint.c: Likewise.
	* corefile.c: Likewise.
	* elfread.c: Likewise.
	* eval.c: Likewise.
	* exceptions.c: Likewise.
	* frame.c: Likewise.
	* gdbarch-selftests.c: Likewise.
	* gnu-v3-abi.c: Likewise.
	* ia64-tdep.c: Likewise.
	* ia64-vms-tdep.c: Likewise.
	* infcall.c: Likewise.
	* infcmd.c: Likewise.
	* infrun.c: Likewise.
	* linespec.c: Likewise.
	* linux-tdep.c: Likewise.
	* minsyms.c: Likewise.
	* ppc-linux-nat.c: Likewise.
	* ppc-linux-tdep.c: Likewise.
	* procfs.c: Likewise.
	* regcache.c: Likewise.
	* remote.c: Likewise.
	* rs6000-tdep.c: Likewise.
	* s390-linux-nat.c: Likewise.
	* s390-tdep.c: Likewise.
	* solib-aix.c: Likewise.
	* solib-darwin.c: Likewise.
	* solib-dsbt.c: Likewise.
	* solib-spu.c: Likewise.
	* solib-svr4.c: Likewise.
	* solib-target.c: Likewise.
	* sparc-tdep.c: Likewise.
	* sparc64-tdep.c: Likewise.
	* spu-tdep.c: Likewise.
	* symfile.c: Likewise.
	* symtab.c: Likewise.
	* target-descriptions.c: Likewise.
	* target-memory.c: Likewise.
	* target.c: Likewise.
	* target.h: Likewise.
	* tracefile-tfile.c: Likewise.
	* tracepoint.c: Likewise.
	* valops.c: Likewise.
	* valprint.c: Likewise.
	* value.c: Likewise.
	* windows-tdep.c: Likewise.
	* mi/mi-main.c: Likewise.

1 files changed, 2 insertions, 2 deletions

diff --git a/gdb/auxv.c b/gdb/auxv.c
index 86a1ba88a67..2afa136efe5 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -291,7 +291,7 @@ target_auxv_parse (gdb_byte **readptr,
   if (gdbarch_auxv_parse_p (gdbarch))
     return gdbarch_auxv_parse (gdbarch, readptr, endptr, typep, valp);
 
-  return target_stack->auxv_parse (readptr, endptr, typep, valp);
+  return current_top_target ()->auxv_parse (readptr, endptr, typep, valp);
 }
 
 
@@ -549,7 +549,7 @@ info_auxv_command (const char *cmd, int from_tty)
     error (_("The program has no auxiliary information now."));
   else
     {
-      int ents = fprint_target_auxv (gdb_stdout, target_stack);
+      int ents = fprint_target_auxv (gdb_stdout, current_top_target ());
 
       if (ents < 0)
 	error (_("No auxiliary vector found, or failed reading it."));