+2004-01-23 J"orn Rennecke <joern.rennecke@superh.com>
+
+ * doc/tm.texi: Insert some weasel words when LOAD_EXTEND_OP
+ may or may not return non-NIL.
+ * postreload.c (reload_cse_simplify_operands): In LOAD_EXTEND_OP code,
+ check CANNOT_CHANGE_MODE_CLASS
+
2004-01-23 Jan Hubicka <jh@suse.cz>
* basic-block.h (PROP_POSTRELOAD): New macro.
Most RISC machines have this property and most CISC machines do not.
@end defmac
-@defmac LOAD_EXTEND_OP (@var{mode})
+@defmac LOAD_EXTEND_OP (@var{mem_mode})
Define this macro to be a C expression indicating when insns that read
-memory in @var{mode}, an integral mode narrower than a word, set the
-bits outside of @var{mode} to be either the sign-extension or the
+memory in @var{mem_mode}, an integral mode narrower than a word, set the
+bits outside of @var{mem_mode} to be either the sign-extension or the
zero-extension of the data read. Return @code{SIGN_EXTEND} for values
-of @var{mode} for which the
+of @var{mem_mode} for which the
insn sign-extends, @code{ZERO_EXTEND} for which it zero-extends, and
@code{NIL} for other modes.
-This macro is not called with @var{mode} non-integral or with a width
+This macro is not called with @var{mem_mode} non-integral or with a width
greater than or equal to @code{BITS_PER_WORD}, so you may return any
value in this case. Do not define this macro if it would always return
@code{NIL}. On machines where this macro is defined, you will normally
define it as the constant @code{SIGN_EXTEND} or @code{ZERO_EXTEND}.
+
+You may return a non-@code{NIL} value even if for some hard registers
+the sign extension is not performed, if for the @code{REGNO_REG_CLASS}
+of these hard registers @code{CANNOT_CHANGE_MODE_CLASS} returns nonzero
+when the @var{from} mode is @var{mem_mode} and the @var{to} mode is any
+integral mode larger than this but not larger than @code{word_mode}.
+
+You must return @code{NIL} if for some hard registers that allow this
+mode, @code{CANNOT_CHANGE_MODE_CLASS} says that they cannot change to
+@code{word_mode}, but that they can change to another integral mode that
+is larger then @var{mem_mode} but still smaller than @code{word_mode}.
@end defmac
@defmac SHORT_IMMEDIATES_SIGN_EXTEND
|| GET_CODE (SET_SRC (set)) == ZERO_EXTEND
|| GET_CODE (SET_SRC (set)) == SIGN_EXTEND)
; /* Continue ordinary processing. */
+#ifdef CANNOT_CHANGE_MODE_CLASS
+ /* If the register cannot change mode to word_mode, it follows that
+ it cannot have been used in word_mode. */
+ else if (GET_CODE (SET_DEST (set)) == REG
+ && CANNOT_CHANGE_MODE_CLASS (GET_MODE (SET_DEST (set)),
+ word_mode,
+ REGNO_REG_CLASS (REGNO (SET_DEST (set)))))
+ ; /* Continue ordinary processing. */
+#endif
/* If this is a straight load, make the extension explicit. */
else if (GET_CODE (SET_DEST (set)) == REG
&& recog_data.n_operands == 2