PR rtl-optimization/20376

	* toplev.c (process_options): Enable -fweb and -frename-registers when
	unrolling.
	* doc/invoke.texi: Update the information about when -fweb and
	-frename-registers are enabled.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@101961 138bc75d-0d04-0410-961f-82ee72b054a4