PR rtl-optimization/70263

	PR rtl-optimization/70263
	* ira.c (memref_used_between_p): Assert we found END in the insn chain.
	(update_equiv_regs): When trying to move a store to after the insn
	that sets the source of the store, make sure the store occurs after
	the insn that sets the source of the store.  When successful note
	the REG_EQUIV note created in the dump file.

	PR rtl-optimization/70263
	* gcc.c-torture/compile/pr70263-1.c: New test.
	* gcc.target/i386/pr70263-2.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@234344 138bc75d-0d04-0410-961f-82ee72b054a4