Special code for equality comparison for Smi, allowing null on left or right without calling deop...

runtime/vm/opt_code_generator_ia32.cc

 // Copyright (c) 2011, 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/opt_code_generator.h"
 
 #include "vm/assembler_macros.h"
@@ skipping 1406 matching lines @@
     __ j(condition, nInfo.true_label());
     __ jmp(nInfo.false_label());
   } else if (nInfo.fallthrough_label() == nInfo.false_label()) {
     __ j(condition, nInfo.true_label());
   } else if (nInfo.fallthrough_label() == nInfo.true_label()) {
     __ j(NegateCondition(condition), nInfo.false_label());
   }
 }
 
 
-// Return false if the code cannot be generated.
+// Generate code under assumption that it is common that a Smi
+// is compared with null.
+// Left argument can be Smi or null, otherwise deoptimize and collect more
+// type information.
+// Right operand can be Smi or null, otherwise call operator on Smi (e.g,
+// when compared with double).
+// This code will be more optimized once we collect types for two arguments.
+void OptimizingCodeGenerator::GenerateSmiEquality(ComparisonNode* node) {
+  ASSERT((node->kind() == Token::kEQ) || (node->kind() == Token::kNE));
+  CodeGenInfo left_info(node->left());
+  CodeGenInfo right_info(node->right());
+  VisitLoadTwo(node->left(), node->right(), EAX, EDX);
+  if (!CodeGenerator::IsResultNeeded(node)) {
+    return;
+  }
+  const Immediate raw_null =
+      Immediate(reinterpret_cast<intptr_t>(Object::null()));
+  Label evaluate_comparison;
+  if (!left_info.IsClass(smi_class_)) {
+    DeoptimizationBlob* deopt_blob = AddDeoptimizationBlob(node, EAX, EDX);
+    Label left_not_null;
+    __ cmpl(EAX, raw_null);
+    __ j(NOT_EQUAL, &left_not_null, Assembler::kNearJump);
+
+    // Left is null, strict compare.
+    __ cmpl(EAX, EDX);
+    __ jmp(&evaluate_comparison, Assembler::kNearJump);
+
+    // Deoptimize if left is not Smi.
+    __ Bind(&left_not_null);
+    __ testl(EAX, Immediate(kSmiTagMask));
+    __ j(NOT_ZERO, deopt_blob->label());
+  }
+  Label done;
+  if (right_info.IsClass(smi_class_)) {
+    __ cmpl(EAX, EDX);
+    // Fall through to evaluate comparison.
+  } else {
+    Label call_operator, inlined_compare;
+    // Test right for being Smi.
+    __ testl(EDX, Immediate(kSmiTagMask));
+    __ j(ZERO, &inlined_compare, Assembler::kNearJump);
+    // Right is not Smi, test it for being null; if so result is false which
+    // is generated by comparing it to left. If right is not null call operator
+    // (could be double).
+    __ cmpl(EDX, raw_null);
+    __ j(NOT_EQUAL, &call_operator, Assembler::kNearJump);
+
+    __ Bind(&inlined_compare);
+    // Left is Smi, right is Smi or Null.
+    __ cmpl(EAX, EDX);
+    __ jmp(&evaluate_comparison);
+
+    __ Bind(&call_operator);
+    // Left is Smi.
+    const int kNumberOfArguments = 2;
+    const Array& kNoArgumentNames = Array::Handle();
+    __ pushl(EAX);
+    __ pushl(EDX);
+    GenerateCheckedInstanceCalls(node,
+                                 node->left(),
+                                 node->id(),
+                                 node->token_index(),
+                                 kNumberOfArguments,
+                                 kNoArgumentNames);
+    __ pushl(EAX);
+    __ jmp(&done, Assembler::kNearJump);
+  }
+  __ Bind(&evaluate_comparison);
+  // Condition is set by a previous comparison operation.
+  Condition condition = OVERFLOW;  // Initialize to something.
+  bool ok = SupportedTokenKindToSmiCondition(node->kind(), &condition);
+  ASSERT(ok);
+  if (NodeInfoHasLabels(node)) {
+    GenerateConditionalJumps(*(node->info()), condition);
+    node->info()->set_labels_used(true);
+  } else {
+    const Bool& bool_true = Bool::ZoneHandle(Bool::True());
+    const Bool& bool_false = Bool::ZoneHandle(Bool::False());
+    Label true_label;
+    __ j(condition, &true_label, Assembler::kNearJump);
+    __ PushObject(bool_false);
+    __ jmp(&done, Assembler::kNearJump);
+    __ Bind(&true_label);
+    __ PushObject(bool_true);
+  }
+  __ Bind(&done);
+}
+
+
+// Return false if the code cannot be generated. It is expected that
+// node->left() is Smi (or null for equality comparison).
 bool OptimizingCodeGenerator::GenerateSmiComparison(ComparisonNode* node) {
+  if ((node->kind() == Token::kEQ) || (node->kind() == Token::kNE)) {
+    GenerateSmiEquality(node);
+    return true;
+  }
   Condition condition;
   if (!SupportedTokenKindToSmiCondition(node->kind(), &condition)) {
     return false;
   }
   const Bool& bool_true = Bool::ZoneHandle(Bool::True());
   const Bool& bool_false = Bool::ZoneHandle(Bool::False());
   CodeGenInfo left_info(node->left());
   CodeGenInfo right_info(node->right());
   VisitLoadTwo(node->left(), node->right(), EAX, EDX);
   if (!CodeGenerator::IsResultNeeded(node)) {
     return true;
   }
-  Label two_smis;
   if (left_info.IsClass(smi_class_) && right_info.IsClass(smi_class_)) {
     __ cmpl(EAX, EDX);
   } else if (left_info.IsClass(smi_class_) || right_info.IsClass(smi_class_)) {
     // One is Smi.
     DeoptimizationBlob* deopt_blob = AddDeoptimizationBlob(node, EAX, EDX);
     Register reg_to_test = left_info.IsClass(smi_class_) ? EDX : EAX;
     __ testl(reg_to_test, Immediate(kSmiTagMask));
     __ j(NOT_ZERO, deopt_blob->label());
     __ cmpl(EAX, EDX);
   } else {
@@ skipping 40 matching lines @@
       return true;
     default:
       return false;
   }
 }
 
 
 // Checks if an inlined equality/non-equality operation can be emitted:
 // - type feedback must exist.
 // - no class in type feedback list overrides '=='.
-// - no Smi class in type feedback class list.
+// - no Smi class in type feedback class list (Smi overrides equality operator).
 bool OptimizingCodeGenerator::GenerateEqualityComparison(ComparisonNode* node) {
   ASSERT((node->kind() == Token::kEQ) || (node->kind() == Token::kNE));
   const Bool& bool_true = Bool::ZoneHandle(Bool::True());
   const Bool& bool_false = Bool::ZoneHandle(Bool::False());
   const ZoneGrowableArray<const Class*>* classes = CollectedClassesAtNode(node);
   if (classes == NULL) {
     return false;
   }
   const int num_classes = classes->length();
   // 'num_classes' can be 0 if the receiver was always null.
@@ skipping 664 matching lines @@
   __ addl(ESP, Immediate(node->arguments()->length() * kWordSize));
   // Result is in EAX.
   if (IsResultNeeded(node)) {
     __ pushl(EAX);
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32