Reduce copying, redundancy & repetition for codegen of comparison instructions

runtime/vm/assembler_mips.h

Index: runtime/vm/assembler_mips.h
diff --git a/runtime/vm/assembler_mips.h b/runtime/vm/assembler_mips.h
index 2236b7fc3d8b6fe6766d4731c71a057ecbdede2f..117f8f9188ea6b113fcbea99baf1ba2454460f22 100644
--- a/runtime/vm/assembler_mips.h
+++ b/runtime/vm/assembler_mips.h
@@ -177,6 +177,12 @@ class Condition : public ValueObject {
     bits_ = RelOpBits::update(value, bits_);
   }
 
+  void SetToInvalidState() {

[Vyacheslav Egorov (Google), 2017/06/15 11:32:46]

Maybe this method should be private?

[erikcorry, 2017/06/19 07:15:08]

Done.

+    bits_ = RelOpBits::update(INVALID_RELATION, bits_);
+  }
+
+  bool IsValid() { return rel_op() != INVALID_RELATION; }
+
   // Uninitialized condition.
   Condition() : ValueObject(), bits_(0) {}

[Vyacheslav Egorov (Google), 2017/06/15 11:32:46]

I would suggest that this one sets bits_ to invalid relation.

[erikcorry, 2017/06/19 07:15:09]

Done.

 
@@ -200,7 +206,11 @@ class Condition : public ValueObject {
     ASSERT((imm != 0) == ((left == IMM) || (right == IMM)));
     set_left(left);
     set_right(right);
-    set_rel_op(rel_op);
+    if (rel_op == INVALID_RELATION) {

[Vyacheslav Egorov (Google), 2017/06/15 11:32:46]

... and here ASSERT(rel_op != INVALID_RELATION)

[erikcorry, 2017/06/19 07:15:09]

I put the assert in the getters for the register numbers.

+      SetToInvalidState();
+    } else {
+      set_rel_op(rel_op);
+    }
     set_imm(imm);
   }