re PR rtl-optimization/46315 (-O2 -fno-strict-overflow causes wrong code generation)

	PR rtl-optimization/46315
	* rtl.h (remove_reg_equal_equiv_notes_for_regno): Declare.
	* rtlanal.c (remove_reg_equal_equiv_notes_for_regno): New function
	extracted from...
	* dce.c (delete_corresponding_reg_eq_notes): ...here.  Rename into...
	(remove_reg_equal_equiv_notes_for_defs): ...this.
	(delete_unmarked_insns): Adjust to above renaming.
	* ifcvt.c (dead_or_predicable): Remove REG_EQUAL and REG_EQUIV notes
	referring to registers set in the insns being moved, if any.

	* df-core.c (df_ref_dump): New function extracted from...
	(df_refs_chain_dump): ...here.  Call it.
	(df_regs_chain_dump): Likewise.
	* df-problems.c (df_chain_dump): Print 'e' for uses in notes.
	* df-scan.c (df_scan_start_dump): Likewise.  Fix long line.

From-SVN: r166827