Stack usage support
	* common.opt (-fstack-usage): New option.
	* doc/invoke.texi (Debugging options): Document it.
	* builtins.c (expand_builtin_apply): Pass TRUE as 4th argument to
	allocate_dynamic_stack_space.
	(expand_builtin_alloca): Add 4th bool parameter CANNOT_ACCUMULATE
	and propagate it to allocate_dynamic_stack_space.
	(expand_builtin) <BUILT_IN_ALLOCA>: Adjust for above change.
	* calls.c (initialize_argument_information): Pass TRUE as 4th
	argument to allocate_dynamic_stack_space.
	(expand_call): Set current_function_has_unbounded_dynamic_stack_size
	to 1 when pushing a variable-sized argument onto the stack.  Pass
	TRUE as 4th argument to allocate_dynamic_stack_space.
	Update current_function_pushed_stack_size.
	(emit_library_call_value_1): Likewise.
	* explow.c (allocate_dynamic_stack_space): Add 4th bool parameter
	CANNOT_ACCUMULATE.  If flag_stack_usage, look into the size and
	attempt to find an upper bound.  Remove redundant code for the
	SETJMP_VIA_SAVE_AREA case.
	* expr.h (allocate_dynamic_stack_space): Add 4th bool parameter.
	* function.h (struct stack_usage): New structure.
	(current_function_static_stack_size): New macro.
	(current_function_dynamic_stack_size): Likewise.
	(current_function_pushed_stack_size): Likewise.
	(current_function_dynamic_alloc_count): Likewise.
	(current_function_has_unbounded_dynamic_stack_size): Likewise.
	(current_function_allocates_dynamic_stack_space): Likewise.
	(struct function): Add new field 'su'.
	* function.c (instantiate_virtual_regs): If SETJMP_VIA_SAVE_AREA,
	add the value of the dynamic offset to the dynamic stack usage.
	(gimplify_parameters): Set ALLOCA_FOR_VAR_P on call to BUILT_IN_ALLOCA
	for variable-sized objects.
	(prepare_function_start): Allocate cfun->su if flag_stack_usage.
	(rest_of_handle_thread_prologue_and_epilogue): Call output_stack_usage.
	* gimplify.c (gimplify_decl_expr): Set ALLOCA_FOR_VAR_P on call to
	BUILT_IN_ALLOCA for variable-sized objects.
	* output.h (output_stack_usage): Declare.
	* toplev.c (stack_usage_file): New file pointer.
	(output_stack_usage): New function.
	(open_auxiliary_file): Likewise.
	(lang_dependent_init): Open file if flag_stack_usage is set.
	(finalize): Close file if stack_usage_file is not null.
	* tree.h (ALLOCA_FOR_VAR_P): New macro.
	* config/alpha/alpha.c (compute_frame_size): New function.
	(alpha_expand_prologue): Use it.
	(alpha_start_function): Likewise.
	(alpha_expand_epilogue): Likewise.  Set stack usage info.
	* config/i386/i386.c (ix86_expand_prologue): Likewise.
	* config/ia64/ia64.c (ia64_expand_prologue): Likewise.
	* config/mips/mips.c (mips_expand_prologue): Likewise.
	* config/pa/pa.c (hppa_expand_prologue): Likewise.
	* config/rs6000/rs6000.c (rs6000_emit_prologue): Likewise.
	* config/sparc/sparc.c (sparc_expand_prologue): Likewise.
testsuite/
	* lib/gcc-dg.exp (cleanup-stack-usage): New procedure.
	* lib/scanasm.exp (scan-stack-usage): Likewise.
	(scan-stack-usage-not): Likewise.
	* gcc.dg/stack-usage-1.c: New test.
	* gcc.target/i386/stack-usage-realign.c: Likewise.

From-SVN: r163660