i386: Don't use frame pointer without stack access

i386: Don't use frame pointer without stack access

When there is no stack access, there is no need to use frame pointer
even if -fno-omit-frame-pointer is used and caller's frame pointer is
unchanged.

gcc/

	PR target/81736
	* config/i386/i386.c (ix86_finalize_stack_realign_flags): Renamed
	to ...
	(ix86_finalize_stack_frame_flags): This.  Also clear
	frame_pointer_needed if -fno-omit-frame-pointer is used without
	stack access.
	(ix86_expand_prologue): Replace ix86_finalize_stack_realign_flags
	with ix86_finalize_stack_frame_flags.
	(ix86_expand_epilogue): Likewise.
	(ix86_expand_split_stack_prologue): Likewise.
	* doc/invoke.texi: Add a note for -fno-omit-frame-pointer.

gcc/testsuite/

	PR target/81736
	* gcc.target/i386/pr81736-1.c: New test.
	* gcc.target/i386/pr81736-2.c: Likewise.
	* gcc.target/i386/pr81736-3.c: Likewise.
	* gcc.target/i386/pr81736-4.c: Likewise.
	* gcc.target/i386/pr81736-5.c: Likewise.
	* gcc.target/i386/pr81736-6.c: Likewise.
	* gcc.target/i386/pr81736-7.c: Likewise.

From-SVN: r251028