VM: Use propagated type to improve checked smi operations in aot compiler.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
diff --git a/runtime/vm/intermediate_language_x64.cc b/runtime/vm/intermediate_language_x64.cc
index 1738532b8acfe29782089f7cdfe2583f659b9f05..21d895ef9f1a88e3b19dfaf62550aed671a8bf70 100644
--- a/runtime/vm/intermediate_language_x64.cc
+++ b/runtime/vm/intermediate_language_x64.cc
@@ -2848,13 +2848,24 @@ void CheckedSmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       new CheckedSmiSlowPath(this, compiler->CurrentTryIndex());
   compiler->AddSlowPathCode(slow_path);
   // Test operands if necessary.
+
+  intptr_t left_cid = left()->Type()->ToCid();
+  intptr_t right_cid = right()->Type()->ToCid();
   Register left = locs()->in(0).reg();
   Register right = locs()->in(1).reg();
-  Register result = locs()->out(0).reg();
-  __ movq(TMP, left);
-  __ orq(TMP, right);
-  __ testq(TMP, Immediate(kSmiTagMask));
+  if (this->left()->definition() == this->right()->definition()) {
+    __ testq(left, Immediate(kSmiTagMask));
+  } else if (left_cid == kSmiCid) {
+    __ testq(right, Immediate(kSmiTagMask));
+  } else if (right_cid == kSmiCid) {
+    __ testq(left, Immediate(kSmiTagMask));
+  } else {
+    __ movq(TMP, left);
+    __ orq(TMP, right);
+    __ testq(TMP, Immediate(kSmiTagMask));
+  }
   __ j(NOT_ZERO, slow_path->entry_label());
+  Register result = locs()->out(0).reg();
   switch (op_kind()) {
     case Token::kADD:
       __ movq(result, left);