[turbofan] Support for combining branches with <Operation>WithOverflow.

src/compiler/instruction-selector-impl.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/linkage.h"
@@ skipping 30 matching lines @@
                                      Register::ToAllocationIndex(reg)));
   }
 
   InstructionOperand* DefineAsFixedDouble(Node* node, DoubleRegister reg) {
     return Define(node, new (zone())
                   UnallocatedOperand(UnallocatedOperand::FIXED_DOUBLE_REGISTER,
                                      DoubleRegister::ToAllocationIndex(reg)));
   }
 
   InstructionOperand* DefineAsConstant(Node* node) {
+    selector()->MarkAsDefined(node);
     sequence()->AddConstant(node->id(), ToConstant(node));
     return ConstantOperand::Create(node->id(), zone());
   }
 
   InstructionOperand* DefineAsLocation(Node* node, LinkageLocation location) {
     return Define(node, ToUnallocatedOperand(location));
   }
 
   InstructionOperand* Use(Node* node) {
     return Use(node,
@@ skipping 111 matching lines @@
         break;
     }
     UNREACHABLE();
     return Constant(static_cast<int32_t>(0));
   }
 
   UnallocatedOperand* Define(Node* node, UnallocatedOperand* operand) {
     ASSERT_NOT_NULL(node);
     ASSERT_NOT_NULL(operand);
     operand->set_virtual_register(node->id());
+    selector()->MarkAsDefined(node);
     return operand;
   }
 
   UnallocatedOperand* Use(Node* node, UnallocatedOperand* operand) {
-    selector_->MarkAsUsed(node);
-    return Define(node, operand);
+    ASSERT_NOT_NULL(node);
+    ASSERT_NOT_NULL(operand);
+    operand->set_virtual_register(node->id());
+    selector()->MarkAsUsed(node);
+    return operand;
   }
 
   UnallocatedOperand* ToUnallocatedOperand(LinkageLocation location) {
     if (location.location_ == LinkageLocation::ANY_REGISTER) {
       return new (zone())
           UnallocatedOperand(UnallocatedOperand::MUST_HAVE_REGISTER);
     }
     if (location.location_ < 0) {
       return new (zone()) UnallocatedOperand(UnallocatedOperand::FIXED_SLOT,
                                              location.location_);
@@ skipping 10 matching lines @@
 };
 
 
 // The flags continuation is a way to combine a branch or a materialization
 // of a boolean value with an instruction that sets the flags register.
 // The whole instruction is treated as a unit by the register allocator, and
 // thus no spills or moves can be introduced between the flags-setting
 // instruction and the branch or set it should be combined with.
 class FlagsContinuation V8_FINAL {
  public:
+  FlagsContinuation() : mode_(kFlags_none) {}
+
   // Creates a new flags continuation from the given condition and true/false
   // blocks.
   FlagsContinuation(FlagsCondition condition, BasicBlock* true_block,
                     BasicBlock* false_block)
       : mode_(kFlags_branch),
         condition_(condition),
         true_block_(true_block),
         false_block_(false_block) {
     ASSERT_NOT_NULL(true_block);
     ASSERT_NOT_NULL(false_block);
   }
 
   // Creates a new flags continuation from the given condition and result node.
   FlagsContinuation(FlagsCondition condition, Node* result)
       : mode_(kFlags_set), condition_(condition), result_(result) {
     ASSERT_NOT_NULL(result);
   }
 
   bool IsNone() const { return mode_ == kFlags_none; }
   bool IsBranch() const { return mode_ == kFlags_branch; }
   bool IsSet() const { return mode_ == kFlags_set; }
-  FlagsCondition condition() const { return condition_; }
+  FlagsCondition condition() const {
+    ASSERT(!IsNone());
+    return condition_;
+  }
   Node* result() const {
     ASSERT(IsSet());
     return result_;
   }
   BasicBlock* true_block() const {
     ASSERT(IsBranch());
     return true_block_;
   }
   BasicBlock* false_block() const {
     ASSERT(IsBranch());
     return false_block_;
   }
 
-  void Negate() { condition_ = static_cast<FlagsCondition>(condition_ ^ 1); }
+  void Negate() {
+    ASSERT(!IsNone());
+    condition_ = static_cast<FlagsCondition>(condition_ ^ 1);
+  }
 
   void Commute() {
+    ASSERT(!IsNone());
     switch (condition_) {
       case kEqual:
       case kNotEqual:
       case kOverflow:
       case kNotOverflow:
         return;
       case kSignedLessThan:
         condition_ = kSignedGreaterThan;
         return;
       case kSignedGreaterThanOrEqual:
@@ skipping 39 matching lines @@
   void OverwriteAndNegateIfEqual(FlagsCondition condition) {
     bool negate = condition_ == kEqual;
     condition_ = condition;
     if (negate) Negate();
   }
 
   void SwapBlocks() { std::swap(true_block_, false_block_); }
 
   // Encodes this flags continuation into the given opcode.
   InstructionCode Encode(InstructionCode opcode) {
-    return opcode | FlagsModeField::encode(mode_) |
-           FlagsConditionField::encode(condition_);
+    opcode |= FlagsModeField::encode(mode_);
+    if (mode_ != kFlags_none) {
+      opcode |= FlagsConditionField::encode(condition_);
+    }
+    return opcode;
   }
 
  private:
   FlagsMode mode_;
   FlagsCondition condition_;
   Node* result_;             // Only valid if mode_ == kFlags_set.
   BasicBlock* true_block_;   // Only valid if mode_ == kFlags_branch.
   BasicBlock* false_block_;  // Only valid if mode_ == kFlags_branch.
 };
 
@@ skipping 18 matching lines @@
   int control_count() { return descriptor->CanLazilyDeoptimize() ? 2 : 0; }
 
   int fixed_and_control_count() { return fixed_count + control_count(); }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_