Embedded constant pools.

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 61 matching lines @@
   void set_predictable_code_size(bool value) { predictable_code_size_ = value; }
 
   uint64_t enabled_cpu_features() const { return enabled_cpu_features_; }
   void set_enabled_cpu_features(uint64_t features) {
     enabled_cpu_features_ = features;
   }
   bool IsEnabled(CpuFeature f) {
     return (enabled_cpu_features_ & (static_cast<uint64_t>(1) << f)) != 0;
   }
 
-  bool is_ool_constant_pool_available() const {
-    if (FLAG_enable_ool_constant_pool) {
-      return ool_constant_pool_available_;
+  bool is_constant_pool_available() const {
+    if (FLAG_enable_embedded_constant_pool) {
+      return constant_pool_available_;
     } else {
-      // Out-of-line constant pool not supported on this architecture.
+      // Embedded constant pool not supported on this architecture.
       UNREACHABLE();
       return false;
     }
   }
 
   // Overwrite a host NaN with a quiet target NaN.  Used by mksnapshot for
   // cross-snapshotting.
   static void QuietNaN(HeapObject* nan) { }
 
   int pc_offset() const { return static_cast<int>(pc_ - buffer_); }
 
   // This function is called when code generation is aborted, so that
   // the assembler could clean up internal data structures.
   virtual void AbortedCodeGeneration() { }
 
   static const int kMinimalBufferSize = 4*KB;
 
  protected:
   // The buffer into which code and relocation info are generated. It could
   // either be owned by the assembler or be provided externally.
   byte* buffer_;
   int buffer_size_;
   bool own_buffer_;
 
-  void set_ool_constant_pool_available(bool available) {
-    if (FLAG_enable_ool_constant_pool) {
-      ool_constant_pool_available_ = available;
+  void set_constant_pool_available(bool available) {
+    if (FLAG_enable_embedded_constant_pool) {
+      constant_pool_available_ = available;
     } else {
-      // Out-of-line constant pool not supported on this architecture.
+      // Embedded constant pool not supported on this architecture.
       UNREACHABLE();
     }
   }
 
   // The program counter, which points into the buffer above and moves forward.
   byte* pc_;
 
  private:
   Isolate* isolate_;
   int jit_cookie_;
   uint64_t enabled_cpu_features_;
   bool emit_debug_code_;
   bool predictable_code_size_;
   bool serializer_enabled_;
 
   // Indicates whether the constant pool can be accessed, which is only possible
   // if the pp register points to the current code object's constant pool.
-  bool ool_constant_pool_available_;
+  bool constant_pool_available_;
 
   // Constant pool.
   friend class FrameAndConstantPoolScope;
   friend class ConstantPoolUnavailableScope;
 };
 
 
 // Avoids emitting debug code during the lifetime of this scope object.
 class DontEmitDebugCodeScope BASE_EMBEDDED {
  public:
@@ skipping 262 matching lines @@
     // Modes <= LAST_COMPACT_ENUM are guaranteed to have compact encoding.
     LAST_COMPACT_ENUM = CODE_TARGET_WITH_ID,
     LAST_STANDARD_NONCOMPACT_ENUM = INTERNAL_REFERENCE_ENCODED
   };
 
   RelocInfo() {}
 
   RelocInfo(byte* pc, Mode rmode, intptr_t data, Code* host)
       : pc_(pc), rmode_(rmode), data_(data), host_(host) {
   }
-  RelocInfo(byte* pc, double data64)
-      : pc_(pc), rmode_(NONE64), data64_(data64), host_(NULL) {
-  }
 
   static inline bool IsRealRelocMode(Mode mode) {
     return mode >= FIRST_REAL_RELOC_MODE &&
         mode <= LAST_REAL_RELOC_MODE;
   }
   static inline bool IsPseudoRelocMode(Mode mode) {
     DCHECK(!IsRealRelocMode(mode));
     return mode >= FIRST_PSEUDO_RELOC_MODE &&
         mode <= LAST_PSEUDO_RELOC_MODE;
   }
@@ skipping 51 matching lines @@
     return mode == DEBUG_BREAK;
   }
   static inline bool IsNone(Mode mode) {
     return mode == NONE32 || mode == NONE64;
   }
   static inline bool IsCodeAgeSequence(Mode mode) {
     return mode == CODE_AGE_SEQUENCE;
   }
   static inline int ModeMask(Mode mode) { return 1 << mode; }
 
-  // Returns true if the first RelocInfo has the same mode and raw data as the
-  // second one.
-  static inline bool IsEqual(RelocInfo first, RelocInfo second) {
-    return first.rmode() == second.rmode() &&
-           (first.rmode() == RelocInfo::NONE64 ?
-              first.raw_data64() == second.raw_data64() :
-              first.data() == second.data());
-  }
-
   // Accessors
   byte* pc() const { return pc_; }
   void set_pc(byte* pc) { pc_ = pc; }
   Mode rmode() const {  return rmode_; }
   intptr_t data() const { return data_; }
-  double data64() const { return data64_; }
-  uint64_t raw_data64() { return bit_cast<uint64_t>(data64_); }
   Code* host() const { return host_; }
   void set_host(Code* host) { host_ = host; }
 
   // Apply a relocation by delta bytes
   INLINE(void apply(intptr_t delta,
                     ICacheFlushMode icache_flush_mode =
                         FLUSH_ICACHE_IF_NEEDED));
 
   // Is the pointer this relocation info refers to coded like a plain pointer
   // or is it strange in some way (e.g. relative or patched into a series of
@@ skipping 122 matching lines @@
       (1 << CODE_TARGET_WITH_ID) | kPositionMask | (1 << COMMENT);
   static const int kApplyMask;  // Modes affected by apply. Depends on arch.
 
  private:
   // On ARM, note that pc_ is the address of the constant pool entry
   // to be relocated and not the address of the instruction
   // referencing the constant pool entry (except when rmode_ ==
   // comment).
   byte* pc_;
   Mode rmode_;
-  union {
-    intptr_t data_;
-    double data64_;
-  };
+  intptr_t data_;
   Code* host_;
   // External-reference pointers are also split across instruction-pairs
   // on some platforms, but are accessed via indirect pointers. This location
   // provides a place for that pointer to exist naturally. Its address
   // is returned by RelocInfo::target_reference_address().
   Address reconstructed_adr_ptr_;
   friend class RelocIterator;
 };
 
 
@@ skipping 498 matching lines @@
 
 class NullCallWrapper : public CallWrapper {
  public:
   NullCallWrapper() { }
   virtual ~NullCallWrapper() { }
   virtual void BeforeCall(int call_size) const { }
   virtual void AfterCall() const { }
 };
 
 
+// -----------------------------------------------------------------------------
+// Embedded constant pool support

[rmcilroy, 2015/06/01 09:52:08]

ConstntPoolEntry is used by both embedded and inline constant pools now right? 
Change the comment here to "Constant pool support" and add one above
ConstantPoolBuilder with "Embedded constant pool support"

[MTBrandyberry, 2015/06/01 21:01:30]

Done.

+
+class ConstantPoolEntry {
+ public:
+  ConstantPoolEntry() {}
+  ConstantPoolEntry(int position, intptr_t value, bool sharing_ok)
+      : position_(position),
+        merged_index_(sharing_ok ? SHARING_ALLOWED : SHARING_PROHIBITED),
+        value_(value) {}
+  ConstantPoolEntry(int position, double value)
+      : position_(position), merged_index_(SHARING_ALLOWED), value64_(value) {}
+
+  int position() const { return position_; }
+  bool sharing_ok() const { return merged_index_ != SHARING_PROHIBITED; }
+  bool is_merged() const { return merged_index_ >= 0; }
+  intptr_t value() const { return value_; }
+  uint64_t value64() const { return bit_cast<uint64_t>(value64_); }
+
+  enum Type { INTPTR, DOUBLE, NUMBER_OF_TYPES };
+
+  static int size(Type type) {
+    return (type == INTPTR) ? kPointerSize : kDoubleSize;
+  }
+
+  enum Access { REGULAR, OVERFLOWED };
+
+ private:
+  int position_;
+  int merged_index_;
+  union {
+    intptr_t value_;
+    double value64_;
+  };
+  enum { SHARING_PROHIBITED = -2, SHARING_ALLOWED = -1 };
+
+  friend class ConstantPoolBuilder;

[rmcilroy, 2015/06/01 09:52:09]

is this only for setting merged_index_? If so, I would prefer to add a
set_merged_index() function rather than requiring that the classes be friended

[MTBrandyberry, 2015/06/01 21:01:30]

Done.

+};
+
+
+class ConstantPoolBuilder BASE_EMBEDDED {
+ public:
+  ConstantPoolBuilder(int ptr_reach_bits, int double_reach_bits);
+
+  // Add pointer-sized constant to the embedded constant pool
+  ConstantPoolEntry::Access AddEntry(int position, intptr_t value,
+                                     bool sharing_ok) {
+    ConstantPoolEntry entry(position, value, sharing_ok);
+    return AddEntry(entry, ConstantPoolEntry::INTPTR);
+  }
+
+  // Add double constant to the embedded constant pool
+  ConstantPoolEntry::Access AddEntry(int position, double value) {
+    ConstantPoolEntry entry(position, value);
+    return AddEntry(entry, ConstantPoolEntry::DOUBLE);
+  }
+
+  // Previews the access type required for the next new entry to be added.
+  ConstantPoolEntry::Access NextAccess(ConstantPoolEntry::Type type) const;
+
+  bool IsEmpty() {
+    return info_[ConstantPoolEntry::INTPTR].entries.empty() &&
+           info_[ConstantPoolEntry::INTPTR].shared_entries.empty() &&
+           info_[ConstantPoolEntry::DOUBLE].entries.empty() &&
+           info_[ConstantPoolEntry::DOUBLE].shared_entries.empty();
+  }
+
+  // Emit the constant pool.  Invoke only after all entries have been
+  // added and all instructions have been emitted.
+  // Returns position of the emitted pool (zero implies no constant pool).
+  int Emit(Assembler* assm);
+
+  // Returns the label associated with the start of the constant pool.
+  // Linking to this label in the function prologue may provide an
+  // efficient means of constant pool pointer register initialization
+  // on some architectures.
+  inline Label* EmittedPosition() { return &emitted_label_; }
+
+ private:
+  ConstantPoolEntry::Access AddEntry(ConstantPoolEntry& entry,
+                                     ConstantPoolEntry::Type type);
+  void EmitSharedEntries(Assembler* assm, ConstantPoolEntry::Type type);
+  void EmitGroup(Assembler* assm, ConstantPoolEntry::Access access,
+                 ConstantPoolEntry::Type type);
+
+  struct PerTypeEntryInfo {
+    PerTypeEntryInfo() : regular_count(0), overflow_start(-1) {}
+    bool overflow() const {
+      return (overflow_start >= 0 &&
+              overflow_start < static_cast<int>(entries.size()));
+    }
+    int regular_reach_bits;
+    int regular_count;
+    int overflow_start;
+    std::vector<ConstantPoolEntry> entries;
+    std::vector<ConstantPoolEntry> shared_entries;
+  };
+
+  Label emitted_label_;  // Records pc_offset of emitted pool
+  PerTypeEntryInfo info_[ConstantPoolEntry::NUMBER_OF_TYPES];
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_