* config/rs6000/rs6000.md (*lt0_disi): New.

From-SVN: r226006

gcc/ChangeLog

 2015-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
 
+	* config/rs6000/rs6000.md (*lt0_disi): New.
+
+2015-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
+
 	PR target/66217
 	* config/rs6000/constraints.md ("S", "T", "t"): Delete.  Update
 	"available letters" comment.

gcc/config/rs6000/rs6000.md

@@ -3475,6 +3475,17 @@
    (set_attr "dot" "yes")
    (set_attr "length" "4,8")])
 
+; Special case for less-than-0.  We can do it with just one machine
+; instruction, but the generic optimizers do not realise it is cheap.
+(define_insn "*lt0_disi"
+  [(set (match_operand:DI 0 "gpc_reg_operand" "=r")
+	(lt:DI (match_operand:SI 1 "gpc_reg_operand" "r")
+	       (const_int 0)))]
+  "TARGET_POWERPC64"
+  "rlwinm %0,%1,1,31,31"
+  [(set_attr "type" "shift")])
+
+
 
 ; Two forms for insert (the two arms of the IOR are not canonicalized,
 ; both are an AND so are the same precedence).