i386: Add a variant peephole for lea rather than ops that clobber CC.

	* config/i386/i386.md (operation on memory peephole): Duplicate an
	existing peephole and adapt it to match lea rather than an operation
	that clobbers CC.

From-SVN: r235443

gcc/ChangeLog

 2016-04-26  Bernd Schmidt  <bschmidt@redhat.com>
 
+	* config/i386/i386.md (operation on memory peephole): Duplicate an
+	existing peephole and adapt it to match lea rather than an operation
+	that clobbers CC.
+
 	PR rtl-optimization/57193
 	* opts.c (default_options_table): Add OPT_frename_registers at -O2
 	and above.

gcc/config/i386/i386.md

@@ -18018,6 +18018,38 @@
 				 operands[5], const0_rtx);
 })
 
+;; Likewise for instances where we have a lea pattern.
+(define_peephole2
+  [(set (match_operand:SWI 0 "register_operand")
+	(match_operand:SWI 1 "memory_operand"))
+   (set (match_operand:SWI 3 "register_operand")
+	(plus (match_dup 0)
+	      (match_operand:SWI 2 "<nonmemory_operand>")))
+   (set (match_dup 1) (match_dup 3))
+   (set (reg FLAGS_REG) (compare (match_dup 3) (const_int 0)))]
+  "(TARGET_READ_MODIFY_WRITE || optimize_insn_for_size_p ())
+   && peep2_reg_dead_p (4, operands[3])
+   && (rtx_equal_p (operands[0], operands[3])
+       || peep2_reg_dead_p (2, operands[0]))
+   && !reg_overlap_mentioned_p (operands[0], operands[1])
+   && !reg_overlap_mentioned_p (operands[3], operands[1])
+   && !reg_overlap_mentioned_p (operands[0], operands[2])
+   && (<MODE>mode != QImode
+       || immediate_operand (operands[2], QImode)
+       || any_QIreg_operand (operands[2], QImode))
+   && ix86_match_ccmode (peep2_next_insn (3), CCGOCmode)"
+  [(parallel [(set (match_dup 4) (match_dup 5))
+	      (set (match_dup 1) (plus:SWI (match_dup 1)
+					   (match_dup 2)))])]
+{
+  operands[4] = SET_DEST (PATTERN (peep2_next_insn (3)));
+  operands[5] = gen_rtx_PLUS (<MODE>mode,
+			      copy_rtx (operands[1]),
+			      copy_rtx (operands[2]));
+  operands[5] = gen_rtx_COMPARE (GET_MODE (operands[4]),
+				 operands[5], const0_rtx);
+})
+
 (define_peephole2
   [(parallel [(set (match_operand:SWI 0 "register_operand")
 		   (match_operator:SWI 2 "plusminuslogic_operator"