New regressions because of ICE in flow.c

[Neil Booth]

This patch appears to be causing a whole load of regressions for
the C compiler:

Sat Mar 30 14:08:55 CET 2002  Jan Hubicka  <jh@suse.cz>

	* local-alloc.c (local_alloc): Avoid call of update_equiv_regs
	* when not optimizing.

	* toplev.c (rest_of_compilation): Cann mark_constant_function
	only when optimizing.

	* flow.c (calculate_global_regs_live): Ensure that all AUX
	* fields are NULL.

	* cfgcleanup.c (bb_flags): Add BB_NONTHREADABLE_BLOCK.
	(thread_jump): Set BB_NONTHREADABLE_BLOCK, check it.
	(try_optimize_cfg): clear all AUX fields.

	* i386.c (aligned_operand): Be prepared for SUBREGed registers.
	(ix86_decompose_address): Use REG_P instead of GET_CODE (...) ==
REG.
	(ix86_address_cost): Be prepared for SUBREGed registers.
	(legitimate_address_p): Accept SUBREGed registers.

One example:

output is:
/home/neil/src/gcc/gcc/testsuite/gcc.c-torture/compile/920409-2.c: In
function `x':
/home/neil/src/gcc/gcc/testsuite/gcc.c-torture/compile/920409-2.c:2:
Internal compiler error in calculate_global_regs_live, at flow.c:1081
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

Neil.