re PR middle-end/34548 (GCC generates too many alignment adds for alloca)

re PR middle-end/34548 (GCC generates too many alignment adds for alloca)

PR 34548

	* function.h (struct rtl_data): Add max_dynamic_stack_alignment.
	* cfgexpand.c (gimple_expand_cfg): Initialise it.
	* explow.c (allocate_dynamic_stack_space): Set it.  Simplify
	alignment requirements given the known alignment of dynamic_offset.
	* function.c (instantiate_virtual_regs): Align dtnamic_offset.

From-SVN: r190051