On Fri, 3 Aug 2012, Ian Lance Taylor wrote:
2012-08-04 Dimitrios Apostolou <ji...@gmx.net>
* libiberty.h
(XOBDELETE,XOBGROW,XOBGROWVEC,XOBSHRINK,XOBSHRINKVEC): New
type-safe macros for obstack allocation.
(XOBFINISH): Renamed argument to PT since it is a pointer to T.
+/* Type-safe obstack allocator. You must first initialize the obstack with
+ obstack_init() or _obstack_begin().
This should recommend obstack_init, or obstack_begin, but not
_obstack_begin. Also obstack_specify_allocation and
obstack_specify_allocation_with_arg are OK, so really it might be
better not to list the functions, but simply say "You must first
initialization the obstack."
Grep reveals that 9 out of 10 times we use _obstack_begin(), and we set
alignment to 0 (isn't it suboptimal?).
+ T: Type, O: Obstack, N: Number of elements, S: raw Size,
s/Size/size/
+#define XOBSHRINK(O, T) obstack_blank ((O), -1 * sizeof (T))
+#define XOBSHRINKVEC(O, T, N) obstack_blank ((O), -1 * sizeof (T) * (N))
These are hard to use safely. I'm not sure we should define them at all.
I've already used XOBSHRINK and it looks clear to me, but I could use
obstack_blank() directly if necessary.
+#define XOBFINISH(O, PT) ((PT) obstack_finish ((O)))
For XOBNEW, etc., we use (T *) rather than (PT). Using (PT) seems
error-probe--it's the only use of the obstack with a different type
parameter. Why not use T rather than PT here, and return (T *)?
I'd have to change many (about 60) occurences of XOBFINISH if I change
that. I'd go for it if I was sure it's what we want, it can be a separate
patch later on.
Thanks,
Dimitris
