i965/fs: Add a helper function for detecting math opcodes.

src/mesa/drivers/dri/i965/brw_fs.cpp

@@ -3138,14 +3138,7 @@ fs_visitor::compute_to_mrf()
 	       /* gen6 math instructions must have the destination be
 		* GRF, so no compute-to-MRF for them.
 		*/
-	       if (scan_inst->opcode == FS_OPCODE_RCP ||
-		   scan_inst->opcode == FS_OPCODE_RSQ ||
-		   scan_inst->opcode == FS_OPCODE_SQRT ||
-		   scan_inst->opcode == FS_OPCODE_EXP2 ||
-		   scan_inst->opcode == FS_OPCODE_LOG2 ||
-		   scan_inst->opcode == FS_OPCODE_SIN ||
-		   scan_inst->opcode == FS_OPCODE_COS ||
-		   scan_inst->opcode == FS_OPCODE_POW) {
+	       if (scan_inst->is_math()) {
 		  break;
 	       }
 	    }

src/mesa/drivers/dri/i965/brw_fs.h

@@ -313,6 +313,18 @@ public:
 	      opcode == FS_OPCODE_TXL);
    }
 
+   bool is_math()
+   {
+      return (opcode == FS_OPCODE_RCP ||
+	      opcode == FS_OPCODE_RSQ ||
+	      opcode == FS_OPCODE_SQRT ||
+	      opcode == FS_OPCODE_EXP2 ||
+	      opcode == FS_OPCODE_LOG2 ||
+	      opcode == FS_OPCODE_SIN ||
+	      opcode == FS_OPCODE_COS ||
+	      opcode == FS_OPCODE_POW);
+   }
+
    int opcode; /* BRW_OPCODE_* or FS_OPCODE_* */
    fs_reg dst;
    fs_reg src[3];