of move instructions to use when clearing memory, c.f. MOVE_RATIO.
[CLEAR_BY_PIECES]: New macro, using CLEAR_RATIO, to determine
whether clear_by_pieces should be used to clear storage.
(clear_storage): Use CLEAR_BY_PIECES instead of MOVE_BY_PIECES.
* doc/tm.texi: Document these two new target macros.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@55429
138bc75d-0d04-0410-961f-
82ee72b054a4
+2002-07-12 Roger Sayle <roger@eyesopen.com>
+
+ * expr.c [CLEAR_RATIO]: New macro defining the maximum number
+ of move instructions to use when clearing memory, c.f. MOVE_RATIO.
+ [CLEAR_BY_PIECES]: New macro, using CLEAR_RATIO, to determine
+ whether clear_by_pieces should be used to clear storage.
+ (clear_storage): Use CLEAR_BY_PIECES instead of MOVE_BY_PIECES.
+
+ * doc/tm.texi: Document these two new target macros.
+
2002-07-12 Stephane Carrez <stcarrez@nerim.fr>
* config/m68hc11/m68hc11.md ("zero_extendsidi2"): Use D_REG only for
A C expression used by @code{move_by_pieces} to determine the largest unit
a load or store used to copy memory is. Defaults to @code{MOVE_MAX}.
+@findex CLEAR_RATIO
+@item CLEAR_RATIO
+The threshold of number of scalar move insns, @emph{below} which a sequence
+of insns should be generated to clear memory instead of a string clear insn
+or a library call. Increasing the value will always make code faster, but
+eventually incurs high cost in increased code size.
+
+If you don't define this, a reasonable default is used.
+
+@findex CLEAR_BY_PIECES_P
+@item CLEAR_BY_PIECES_P (@var{size}, @var{alignment})
+A C expression used to determine whether @code{clear_by_pieces} will be used
+to clear a chunk of memory, or whether some other block clear mechanism
+will be used. Defaults to 1 if @code{move_by_pieces_ninsns} returns less
+than @code{CLEAR_RATIO}.
+
@findex USE_LOAD_POST_INCREMENT
@item USE_LOAD_POST_INCREMENT (@var{mode})
A C expression used to determine whether a load postincrement is a good
(move_by_pieces_ninsns (SIZE, ALIGN) < (unsigned int) MOVE_RATIO)
#endif
+/* If a clear memory operation would take CLEAR_RATIO or more simple
+ move-instruction sequences, we will do a clrstr or libcall instead. */
+
+#ifndef CLEAR_RATIO
+#if defined (HAVE_clrstrqi) || defined (HAVE_clrstrhi) || defined (HAVE_clrstrsi) || defined (HAVE_clrstrdi) || defined (HAVE_clrstrti)
+#define CLEAR_RATIO 2
+#else
+/* If we are optimizing for space, cut down the default clear ratio. */
+#define CLEAR_RATIO (optimize_size ? 3 : 15)
+#endif
+#endif
+
+/* This macro is used to determine whether clear_by_pieces should be
+ called to clear storage. */
+#ifndef CLEAR_BY_PIECES_P
+#define CLEAR_BY_PIECES_P(SIZE, ALIGN) \
+ (move_by_pieces_ninsns (SIZE, ALIGN) < (unsigned int) CLEAR_RATIO)
+#endif
+
/* This array records the insn_code of insns to perform block moves. */
enum insn_code movstr_optab[NUM_MACHINE_MODES];
size = protect_from_queue (size, 0);
if (GET_CODE (size) == CONST_INT
- && MOVE_BY_PIECES_P (INTVAL (size), align))
+ && CLEAR_BY_PIECES_P (INTVAL (size), align))
clear_by_pieces (object, INTVAL (size), align);
else
{