ART: Refactor GraphVisualizer attribute printing

This patch unifies the way GraphVisualizer prints instruction
attributes in preparation of changes to the Checker syntax.

Change-Id: I44e91e36c660985ddfe039a9f410fedc48b496ec
diff --git a/test/445-checker-licm/src/Main.java b/test/445-checker-licm/src/Main.java
index 91ac2ed..c7a5f04 100644
--- a/test/445-checker-licm/src/Main.java
+++ b/test/445-checker-licm/src/Main.java
@@ -17,13 +17,13 @@
 public class Main {
 
   // CHECK-START: int Main.div() licm (before)
-  // CHECK-DAG: Div ( loop_header:{{B\d+}} )
+  // CHECK-DAG: Div loop:{{B\d+}}
 
   // CHECK-START: int Main.div() licm (after)
-  // CHECK-NOT: Div ( loop_header:{{B\d+}} )
+  // CHECK-NOT: Div loop:{{B\d+}}
 
   // CHECK-START: int Main.div() licm (after)
-  // CHECK-DAG: Div ( loop_header:null )
+  // CHECK-DAG: Div loop:none
 
   public static int div() {
     int result = 0;
@@ -34,13 +34,13 @@
   }
 
   // CHECK-START: int Main.innerDiv() licm (before)
-  // CHECK-DAG: Div ( loop_header:{{B\d+}} )
+  // CHECK-DAG: Div loop:{{B\d+}}
 
   // CHECK-START: int Main.innerDiv() licm (after)
-  // CHECK-NOT: Div ( loop_header:{{B\d+}} )
+  // CHECK-NOT: Div loop:{{B\d+}}
 
   // CHECK-START: int Main.innerDiv() licm (after)
-  // CHECK-DAG: Div ( loop_header:null )
+  // CHECK-DAG: Div loop:none
 
   public static int innerDiv() {
     int result = 0;
@@ -53,10 +53,10 @@
   }
 
   // CHECK-START: int Main.innerDiv2() licm (before)
-  // CHECK-DAG: Mul ( loop_header:{{B4}} )
+  // CHECK-DAG: Mul loop:B4
 
   // CHECK-START: int Main.innerDiv2() licm (after)
-  // CHECK-DAG: Mul ( loop_header:{{B2}} )
+  // CHECK-DAG: Mul loop:B2
 
   public static int innerDiv2() {
     int result = 0;
@@ -72,10 +72,10 @@
   }
 
   // CHECK-START: int Main.innerDiv3(int, int) licm (before)
-  // CHECK-DAG: Div ( loop_header:{{B\d+}} )
+  // CHECK-DAG: Div loop:{{B\d+}}
 
   // CHECK-START: int Main.innerDiv3(int, int) licm (after)
-  // CHECK-DAG: Div ( loop_header:{{B\d+}} )
+  // CHECK-DAG: Div loop:{{B\d+}}
 
   public static int innerDiv3(int a, int b) {
     int result = 0;
@@ -88,16 +88,16 @@
   }
 
   // CHECK-START: int Main.arrayLength(int[]) licm (before)
-  // CHECK-DAG: [[NullCheck:l\d+]] NullCheck ( loop_header:{{B\d+}} )
-  // CHECK-DAG:                    ArrayLength [ [[NullCheck]] ] ( loop_header:{{B\d+}} )
+  // CHECK-DAG: [[NullCheck:l\d+]] NullCheck loop:{{B\d+}}
+  // CHECK-DAG:                    ArrayLength [ [[NullCheck]] ] loop:{{B\d+}}
 
   // CHECK-START: int Main.arrayLength(int[]) licm (after)
-  // CHECK-NOT:                    NullCheck ( loop_header:{{B\d+}} )
-  // CHECK-NOT:                    ArrayLength ( loop_header:{{B\d+}} )
+  // CHECK-NOT:                    NullCheck loop:{{B\d+}}
+  // CHECK-NOT:                    ArrayLength loop:{{B\d+}}
 
   // CHECK-START: int Main.arrayLength(int[]) licm (after)
-  // CHECK-DAG: [[NullCheck:l\d+]] NullCheck ( loop_header:null )
-  // CHECK-DAG:                    ArrayLength [ [[NullCheck]] ] ( loop_header:null )
+  // CHECK-DAG: [[NullCheck:l\d+]] NullCheck loop:none
+  // CHECK-DAG:                    ArrayLength [ [[NullCheck]] ] loop:none
 
   public static int arrayLength(int[] array) {
     int result = 0;