Initial commit from sysy-main

test/22_test_dce.sy

@@ -0,0 +1,15 @@
+//test file for dead code eliminiation (dce) 
+int main(){
+
+    int i = 0;
+    int j = 0; 
+    int a[100];
+
+    while(j < 100){
+        a[j] = j;
+        i = i * 2;
+        j = j + 1;
+    }
+
+    return a[j-1];
+}