Use stack locations instead of register for binary Smi operations when possible.

runtime/vm/intermediate_language_ia32.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_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 2294 matching lines @@
     if (!is_truncating()) {
       summary->AddTemp(Location::RequiresRegister());
     }
     summary->set_out(Location::SameAsFirstInput());
     return summary;
   } else {
     const intptr_t kNumTemps = 0;
     LocationSummary* summary =
         new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresRegister());
-    summary->set_in(1, Location::RegisterOrSmiConstant(right()));
+    ConstantInstr* constant = right()->definition()->AsConstant();
+    if (constant != NULL) {
+      summary->set_in(1, Location::RegisterOrSmiConstant(right()));
+    } else {
+      summary->set_in(1, Location::Any());

[Florian Schneider, 2013/05/28 10:09:37]

We also have Location::PrefersRegister() as an alternative. The difference is
that if there is a free register and the value is spilled, it will go into the
free register. If all registers are occupied, it will be on the stack.

I think PrefersRegister() would be better than Any(), but it should be confirmed
with a measurement.

[srdjan, 2013/05/28 10:39:01]

Changed to PrefersRegister, no significant difference in performance observed.

+    }
     summary->set_out(Location::SameAsFirstInput());
     return summary;
   }
 }
 
 
 void BinarySmiOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (op_kind() == Token::kSHL) {
     EmitSmiShiftLeft(compiler, this);
     return;
@@ skipping 100 matching lines @@
         __ sarl(left, Immediate(value));
         __ SmiTag(left);
         break;
       }
 
       default:
         UNREACHABLE();
         break;
     }
     return;
-  }
+  }  // if locs()->in(1).IsConstant()
 
+  if (locs()->in(1).IsStackSlot()) {
+    const Address& right = locs()->in(1).ToStackSlotAddress();
+    switch (op_kind()) {
+      case Token::kADD: {
+        __ addl(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kSUB: {
+        __ subl(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kMUL: {
+        __ SmiUntag(left);
+        __ imull(left, right);
+        if (deopt != NULL) __ j(OVERFLOW, deopt);
+        break;
+      }
+      case Token::kBIT_AND: {
+        // No overflow check.
+        __ andl(left, right);
+        break;
+      }
+      case Token::kBIT_OR: {
+        // No overflow check.
+        __ orl(left, right);
+        break;
+      }
+      case Token::kBIT_XOR: {
+        // No overflow check.
+        __ xorl(left, right);
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+    return;
+  }  // if locs()->in(1).IsStackSlot.
+
+  // if locs()->in(1).IsRegister.
   Register right = locs()->in(1).reg();
   switch (op_kind()) {
     case Token::kADD: {
       __ addl(left, right);
       if (deopt != NULL) __ j(OVERFLOW, deopt);
       break;
     }
     case Token::kSUB: {
       __ subl(left, right);
       if (deopt != NULL) __ j(OVERFLOW, deopt);
@@ skipping 2252 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32