gcc stack-smashing protector (for gcc-3.0 20010507)

[Hiroaki Etoh]

 This patch introduces -fstack-protector option, which is a stack-smashing 
protection mechanism to the latest snapshot (3.0 20010507).
This patch and new files (protector.h and protector.c) are bootstraped
and tested on i386-pc-linux-gnu and powerpc-ibm-aix4.3.3.0.

Please see the web page
( http://www.trl.ibm.co.jp/projects/security/ssp/ ) for details and
what is a stack-smashing protection.

Hiroaki Etoh,  Tokyo Research Laboratory, IBM Japan

2001-05-18  Hiroaki Etoh  <etoh@jp.ibm.com>

	* Add -fstack-protector option, which enables generating the stack
	protection code to detect buffer overflow and the stop its
	execution
	
	* protector.c: New file
	* protector.h: New file

	* Makefile.in: Add new file protector.c and new library member
	_stack_smash_handler in libgcc2.c
	* builtins.c (get_memory_rtx): Specify EXPAND_NORMAL as an argument of
	expand_expr in the case of using stack smashing protection
	* cse.c (cse_insn): Don't record equivalence of the register that
	duplicates a pointer in a function argument to prevent the corruption
	of buffer overflow
	* dbxout.c (dbxout_parms): Change the debug info of duplicated
	pointer argument in the case of using stack smashing protection
	* expr.c (expand_expr):  Specify ro_modifier in stead of EXPAND_SUM as
	an argument of expand_expr in the case of stack smashing protection
	* function.c (assign_stack_temp_for_type, combine_temp_slots): Add the
	special handling of character buffer for the reuse of
	allocated stack space
	* function.c (put_reg_into_stack): Change the location of allocated
	stack area for the spilled-out pseuso register in the case of stack
	smashing protection
	* gcse.c (cprop_insn): Don't eliminate the register that duplicates
	a pointer in a function argument to prevent the corruption
	of buffer overflow
	* integrate.c (expand_inline_function): Specify EXPAND_NORMAL as an
	argument of expand_expr in the case of using stack smashing protection
	* libgcc2.c (__guard_setup, __stack_smash_handler): New function.
	* reload1.c (alter_reg): Change the location of allocated stack area
	for the spilled-out pseuso register in the case of
	stack smashing protection
	* toplev.c (rest_of_compilation, f_options): Add the function of
	stack smashing protection