Merge 6168:6800 from bleeding_edge to experimental/gc branch.

src/safepoint-table.h

-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 11 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_SAFEPOINT_TABLE_H_
 #define V8_SAFEPOINT_TABLE_H_
 
 #include "v8.h"
 
-#include "macro-assembler.h"
+#include "heap.h"
 #include "zone.h"
 #include "zone-inl.h"
 
 namespace v8 {
 namespace internal {
 
+struct Register;
+
+class SafepointEntry BASE_EMBEDDED {
+ public:
+  SafepointEntry() : info_(0), bits_(NULL) {}
+
+  SafepointEntry(unsigned info, uint8_t* bits) : info_(info), bits_(bits) {
+    ASSERT(is_valid());
+  }
+
+  bool is_valid() const { return bits_ != NULL; }
+
+  bool Equals(const SafepointEntry& other) const {
+    return info_ == other.info_ && bits_ == other.bits_;
+  }
+
+  void Reset() {
+    info_ = 0;
+    bits_ = NULL;
+  }
+
+  int deoptimization_index() const {
+    ASSERT(is_valid());
+    return DeoptimizationIndexField::decode(info_);
+  }
+
+  int gap_code_size() const {
+    ASSERT(is_valid());
+    return GapCodeSizeField::decode(info_);
+  }
+
+  int argument_count() const {
+    ASSERT(is_valid());
+    return ArgumentsField::decode(info_);
+  }
+
+  bool has_doubles() const {
+    ASSERT(is_valid());
+    return SaveDoublesField::decode(info_);
+  }
+
+  uint8_t* bits() {
+    ASSERT(is_valid());
+    return bits_;
+  }
+
+  bool HasRegisters() const;
+  bool HasRegisterAt(int reg_index) const;
+
+  // Reserve 13 bits for the gap code size. On ARM a constant pool can be
+  // emitted when generating the gap code. The size of the const pool is less
+  // than what can be represented in 12 bits, so 13 bits gives room for having
+  // instructions before potentially emitting a constant pool.
+  static const int kGapCodeSizeBits = 13;
+  static const int kArgumentsFieldBits = 3;
+  static const int kSaveDoublesFieldBits = 1;
+  static const int kDeoptIndexBits =
+      32 - kGapCodeSizeBits - kArgumentsFieldBits - kSaveDoublesFieldBits;
+  class GapCodeSizeField: public BitField<unsigned, 0, kGapCodeSizeBits> {};
+  class DeoptimizationIndexField: public BitField<int,
+                                                  kGapCodeSizeBits,
+                                                  kDeoptIndexBits> {};  // NOLINT
+  class ArgumentsField: public BitField<unsigned,
+                                        kGapCodeSizeBits + kDeoptIndexBits,
+                                        kArgumentsFieldBits> {};  // NOLINT
+  class SaveDoublesField: public BitField<bool,
+                                          kGapCodeSizeBits + kDeoptIndexBits +
+                                          kArgumentsFieldBits,
+                                          kSaveDoublesFieldBits> { }; // NOLINT
+
+ private:
+  unsigned info_;
+  uint8_t* bits_;
+};
+
+
 class SafepointTable BASE_EMBEDDED {
  public:
   explicit SafepointTable(Code* code);
 
   int size() const {
     return kHeaderSize +
            (length_ * (kPcAndDeoptimizationIndexSize + entry_size_)); }
   unsigned length() const { return length_; }
   unsigned entry_size() const { return entry_size_; }
 
   unsigned GetPcOffset(unsigned index) const {
     ASSERT(index < length_);
     return Memory::uint32_at(GetPcOffsetLocation(index));
   }
 
-  int GetDeoptimizationIndex(unsigned index) const {
+  SafepointEntry GetEntry(unsigned index) const {
     ASSERT(index < length_);
-    unsigned value = Memory::uint32_at(GetDeoptimizationLocation(index));
-    return DeoptimizationIndexField::decode(value);
+    unsigned info = Memory::uint32_at(GetInfoLocation(index));
+    uint8_t* bits = &Memory::uint8_at(entries_ + (index * entry_size_));
+    return SafepointEntry(info, bits);
   }
 
-  unsigned GetGapCodeSize(unsigned index) const {
-    ASSERT(index < length_);
-    unsigned value = Memory::uint32_at(GetDeoptimizationLocation(index));
-    return GapCodeSizeField::decode(value);
-  }
-
-  uint8_t* GetEntry(unsigned index) const {
-    ASSERT(index < length_);
-    return &Memory::uint8_at(entries_ + (index * entry_size_));
-  }
-
-  class GapCodeSizeField: public BitField<unsigned, 0, 8> {};
-  class DeoptimizationIndexField: public BitField<int, 8, 24> {};
-
-  static bool HasRegisters(uint8_t* entry);
-  static bool HasRegisterAt(uint8_t* entry, int reg_index);
+  // Returns the entry for the given pc.
+  SafepointEntry FindEntry(Address pc) const;
 
   void PrintEntry(unsigned index) const;
 
  private:
   static const uint8_t kNoRegisters = 0xFF;
 
   static const int kLengthOffset = 0;
   static const int kEntrySizeOffset = kLengthOffset + kIntSize;
   static const int kHeaderSize = kEntrySizeOffset + kIntSize;
 
   static const int kPcSize = kIntSize;
   static const int kDeoptimizationIndexSize = kIntSize;
   static const int kPcAndDeoptimizationIndexSize =
       kPcSize + kDeoptimizationIndexSize;
 
   Address GetPcOffsetLocation(unsigned index) const {
     return pc_and_deoptimization_indexes_ +
            (index * kPcAndDeoptimizationIndexSize);
   }
 
-  Address GetDeoptimizationLocation(unsigned index) const {
+  Address GetInfoLocation(unsigned index) const {
     return GetPcOffsetLocation(index) + kPcSize;
   }
 
   static void PrintBits(uint8_t byte, int digits);
 
   AssertNoAllocation no_allocation_;
   Code* code_;
   unsigned length_;
   unsigned entry_size_;
 
   Address pc_and_deoptimization_indexes_;
   Address entries_;
 
   friend class SafepointTableBuilder;
+  friend class SafepointEntry;
+
+  DISALLOW_COPY_AND_ASSIGN(SafepointTable);
 };
 
 
 class Safepoint BASE_EMBEDDED {
  public:
-  static const int kNoDeoptimizationIndex = 0x00ffffff;
+  typedef enum {
+    kSimple = 0,
+    kWithRegisters = 1 << 0,
+    kWithDoubles = 1 << 1,
+    kWithRegistersAndDoubles = kWithRegisters | kWithDoubles
+  } Kind;
+
+  static const int kNoDeoptimizationIndex =
+      (1 << (SafepointEntry::kDeoptIndexBits)) - 1;
 
   void DefinePointerSlot(int index) { indexes_->Add(index); }
-  void DefinePointerRegister(Register reg) { registers_->Add(reg.code()); }
+  void DefinePointerRegister(Register reg);
 
  private:
   Safepoint(ZoneList<int>* indexes, ZoneList<int>* registers) :
       indexes_(indexes), registers_(registers) { }
   ZoneList<int>* indexes_;
   ZoneList<int>* registers_;
 
   friend class SafepointTableBuilder;
 };
 
 
 class SafepointTableBuilder BASE_EMBEDDED {
  public:
   SafepointTableBuilder()
       : deoptimization_info_(32),
         indexes_(32),
         registers_(32),
         emitted_(false) { }
 
   // Get the offset of the emitted safepoint table in the code.
   unsigned GetCodeOffset() const;
 
   // Define a new safepoint for the current position in the body.
-  Safepoint DefineSafepoint(
-      Assembler* assembler,
-      int deoptimization_index = Safepoint::kNoDeoptimizationIndex);
+  Safepoint DefineSafepoint(Assembler* assembler,
+                            Safepoint::Kind kind,
+                            int arguments,
+                            int deoptimization_index);
 
-  // Define a new safepoint with registers on the stack for the
-  // current position in the body and take the number of arguments on
-  // top of the registers into account.
-  Safepoint DefineSafepointWithRegisters(
-      Assembler* assembler,
-      int arguments,
-      int deoptimization_index = Safepoint::kNoDeoptimizationIndex);
-
-  // Update the last safepoint with the size of the code generated for the gap
-  // following it.
+  // Update the last safepoint with the size of the code generated until the
+  // end of the gap following it.
   void SetPcAfterGap(int pc) {
     ASSERT(!deoptimization_info_.is_empty());
     int index = deoptimization_info_.length() - 1;
     deoptimization_info_[index].pc_after_gap = pc;
   }
 
   // Emit the safepoint table after the body. The number of bits per
   // entry must be enough to hold all the pointer indexes.
   void Emit(Assembler* assembler, int bits_per_entry);
 
+  // Count the number of deoptimization points where the next
+  // following deoptimization point comes less than limit bytes
+  // after the end of this point's gap.
+  int CountShortDeoptimizationIntervals(unsigned limit);
+
  private:
   struct DeoptimizationInfo {
     unsigned pc;
     unsigned deoptimization_index;
     unsigned pc_after_gap;
+    unsigned arguments;
+    bool has_doubles;
   };
 
-  uint32_t EncodeDeoptimizationIndexAndGap(DeoptimizationInfo info);
+  uint32_t EncodeExceptPC(const DeoptimizationInfo& info);
 
   ZoneList<DeoptimizationInfo> deoptimization_info_;
   ZoneList<ZoneList<int>*> indexes_;
   ZoneList<ZoneList<int>*> registers_;
 
+  unsigned offset_;
   bool emitted_;
-  unsigned offset_;
 
   DISALLOW_COPY_AND_ASSIGN(SafepointTableBuilder);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SAFEPOINT_TABLE_H_