PR target/80969 - Fix ICE with -mabi=ms -mavx512f, reduce wasted space when realignin...

PR target/80969 - Fix ICE with -mabi=ms -mavx512f, reduce wasted space when realigning stack.

2017-08-23  Daniel Santos  <daniel.santos@pobox.com>

	* config/i386/i386.h (ix86_frame::stack_realign_allocate_offset):
	Remove field.
	(ix86_frame::stack_realign_allocate): New field.
	(struct machine_frame_state): Modify comments.
	(machine_frame_state::sp_realigned_fp_end): New field.
	* config/i386/i386.c (ix86_compute_frame_layout): Rework stack frame
	layout calculation.
	(sp_valid_at): Add assertion to assure no attempt to access invalid
	offset of a realigned stack.
	(fp_valid_at): Likewise.
	(choose_baseaddr): Modify comments.
	(ix86_emit_outlined_ms2sysv_save): Adjust to changes in
	ix86_expand_prologue.
	(ix86_expand_prologue): Modify stack realignment and allocation.
	(ix86_expand_epilogue): Modify comments.
	* doc/sourcebuild.texi: Add documentation for target selectors avx2,
	avx2_runtime, avx512f, and avx512f_runtime.

2017-08-23  Daniel Santos  <daniel.santos@pobox.com>

	* gcc.target/i386/pr80969-1.c: New testcase.
	* gcc.target/i386/pr80969-2a.c: Likewise.
	* gcc.target/i386/pr80969-2.c: Likewise.
	* gcc.target/i386/pr80969-3.c: Likewise.
	* gcc.target/i386/pr80969-4a.c: Likewise.
	* gcc.target/i386/pr80969-4b.c: Likewise.
	* gcc.target/i386/pr80969-4.c: Likewise.
	* gcc.target/i386/pr80969-4.h: New header common to pr80969-4*.c
	* lib/target-supports.exp (check_avx512_os_support_available,
	check_avx512f_hw_available, check_effective_target_avx512f_runtime):
	New proceedures for target avx512f and avx512f_runtime selectors.
	(check_avx2_hw_available): Fix breakage due NULL being undefined.

From-SVN: r251321