re PR target/18002 ('while' loop performace regression on avr target)

re PR target/18002 ('while' loop performace regression on avr target)

	PR target/18002
	PR middle-end/18424
	Backport from mainline

	2004-03-20  Richard Sandiford  <rsandifo@redhat.com>
	* Makefile.in (dojump.o): Depend on $(GGC_H) and dojump.h.
	(GTFILES): Add $(srcdir)/dojump.h.
	(gt-dojump.h): New dependency.
	* dojump.c (and_reg, and_test, shift_test): New static variables.
	(prefer_and_bit_test): New function.
	(do_jump): Use it to choose between (X & (1 << C)) and (X >> C) & 1.

	2004-03-21  Andrew Pinski  <pinskia@gcc.gnu.org>
	* dojump.c (prefer_and_bit_test): Fix which part of
	the and_test is replaced.

	2004-12-10  Roger Sayle  <roger@eyesopen.com>
	* dojump.c (do_jump): When attempting to reverse the effects of
	fold_single_bit_test, we need to STRIP_NOPS and narrowing type
	conversions, and handle BIT_XOR_EXPR that's used to invert the
	sense of the single bit test.

From-SVN: r92117