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

runtime/vm/intermediate_language_mips.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/compiler.h"
@@ skipping 2910 matching lines @@
 
 
 void CheckedSmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   CheckedSmiSlowPath* slow_path =
       new CheckedSmiSlowPath(this, compiler->CurrentTryIndex());
   compiler->AddSlowPathCode(slow_path);
   // Test operands if necessary.
   Register left = locs()->in(0).reg();
   Register right = locs()->in(1).reg();
   Register result = locs()->out(0).reg();
-  __ or_(result, left, right);
-  __ andi(CMPRES1, result, Immediate(kSmiTagMask));
+  intptr_t left_cid = this->left()->Type()->ToCid();
+  intptr_t right_cid = this->right()->Type()->ToCid();
+  bool combined_smi_check = false;
+  if (this->left()->definition() == this->right()->definition()) {
+    __ andi(CMPRES1, left, Immediate(kSmiTagMask));
+  } else if (left_cid == kSmiCid) {
+    __ andi(CMPRES1, right, Immediate(kSmiTagMask));
+  } else if (right_cid == kSmiCid) {
+    __ andi(CMPRES1, left, Immediate(kSmiTagMask));
+  } else {
+    combined_smi_check = true;
+    __ or_(result, left, right);
+    __ andi(CMPRES1, result, Immediate(kSmiTagMask));
+  }
   __ bne(CMPRES1, ZR, slow_path->entry_label());
   switch (op_kind()) {
     case Token::kADD:
       __ AdduDetectOverflow(result, left, right, CMPRES1);
       __ bltz(CMPRES1, slow_path->entry_label());
       break;
     case Token::kSUB:
       __ SubuDetectOverflow(result, left, right, CMPRES1);
       __ bltz(CMPRES1, slow_path->entry_label());
       break;
     case Token::kBIT_OR:
       // Operation part of combined smi check.
+      if (!combined_smi_check) {
+        __ or_(result, left, right);
+      }
       break;
     case Token::kBIT_AND:
       __ and_(result, left, right);
       break;
     case Token::kBIT_XOR:
       __ xor_(result, left, right);
       break;
     case Token::kEQ:
     case Token::kLT:
     case Token::kLTE:
@@ skipping 2732 matching lines @@
                                 1,
                                 locs());
   __ lw(result, Address(SP, 1 * kWordSize));
   __ addiu(SP, SP, Immediate(2 * kWordSize));
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS