PR optimization/10876
	* config/sparc/sparc.h (CONST_OK_FOR_LETTER): Add
	new 'O' constraint for constant 4096.
	(CONST_DOUBLE_OK_FOR_LETTER_P): Likewise.
	* config/sparc/sparc.md (adddi3 expander): Canonicalize pattern.
	Do not transform into MINUS insn for constant 4096.
	(*adddi3_sp64 insn): Canonicalize pattern. Add new alternative
	for constant 4096 as third operand.
	(addsi3 expander): Remove.
	(*addsi3 insn): Rename into 'addsi3'. Canonicalize pattern. Add
	new alternative for constant 4096 as third operand.
	(subdi3 expander): Do not transform into PLUS insn for constant 4096.
	(*subdi3_sp64 insn): Add new alternative for constant 4096 as third
	operand.
	(subsi3 expander): Remove.
	(*subsi3 insn): Rename into 'subsi3'. Add new alternative for
	constant 4096 as third operand.
	* doc/md.texi (Machine Constraints): Document new 'O' constraint for
	the SPARC port.

From-SVN: r67426