[Courgette] Using LabelManager to reduce Courgette-apply peak RAM by 25%.

courgette/disassembler.h

 // Copyright (c) 2011 The Chromium 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 COURGETTE_DISASSEMBLER_H_
 #define COURGETTE_DISASSEMBLER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include <vector>
+
 #include "base/macros.h"
 #include "courgette/courgette.h"
 #include "courgette/image_utils.h"
 
 namespace courgette {
 
 class AssemblyProgram;
 
 class Disassembler : public AddressTranslator {
  public:
+  // Visitor/adaptor to translate RVA to target RVA for abs32.
+  class RvaVisitor_Abs32 : public VectorRvaVisitor<RVA> {
+   public:
+    RvaVisitor_Abs32(const std::vector<RVA>& rva_locations,
+                     const AddressTranslator& translator);
+    ~RvaVisitor_Abs32() override { }
+
+    // VectorRvaVisitor<RVA> interfaces.
+    RVA Get() const override;
+
+   private:
+    const AddressTranslator& translator_;
+
+    DISALLOW_COPY_AND_ASSIGN(RvaVisitor_Abs32);
+  };
+
+  // Visitor/adaptor to translate RVA to target RVA for rel32.
+  class RvaVisitor_Rel32 : public VectorRvaVisitor<RVA> {
+   public:
+    RvaVisitor_Rel32(const std::vector<RVA>& rva_locations,
+                     const AddressTranslator& translator);
+    ~RvaVisitor_Rel32() override { }
+
+    // VectorRvaVisitor<RVA> interfaces.
+    RVA Get() const override;
+
+   private:
+    const AddressTranslator& translator_;
+
+    DISALLOW_COPY_AND_ASSIGN(RvaVisitor_Rel32);
+  };
+
   virtual ~Disassembler();
 
   // AddressTranslator interfaces.
   virtual RVA FileOffsetToRVA(FileOffset file_offset) const override = 0;
   virtual FileOffset RVAToFileOffset(RVA rva) const override = 0;
   const uint8_t* FileOffsetToPointer(FileOffset file_offset) const override;
   const uint8_t* RVAToPointer(RVA rva) const override;
   RVA PointerToTargetRVA(const uint8_t* p) const = 0;
 
   virtual ExecutableType kind() const = 0;
 
+  // Returns a caller-owned new RvaVisitor to iterate through abs32 target RVAs.
+  virtual RvaVisitor* CreateAbs32TargetRvaVisitor() = 0;
+
+  // Returns a caller-owned new RvaVisitor to iterate through rel32 target RVAs.
+  virtual RvaVisitor* CreateRel32TargetRvaVisitor() = 0;
+
+  // Removes unused rel32 locations (architecture-specific). This is needed
+  // because we may remove rel32 Labels along the way. As a result the matching
+  // matching rel32 addresses become unused. Removing them saves space.
+  virtual void RemoveUnusedRel32Locations(AssemblyProgram* program) = 0;
+
   // Returns true if the buffer appears to be a valid executable of the expected
   // type, and false otherwise. This needs not be called before Disassemble().
   virtual bool ParseHeader() = 0;
 
   // Disassembles the item passed to the factory method into the output
   // parameter 'program'.
   virtual bool Disassemble(AssemblyProgram* program) = 0;
 
   // ok() may always be called but returns true only after ParseHeader()
   // succeeds.
   bool ok() const { return failure_reason_ == nullptr; }
 
   // Returns the length of the image. May reduce after ParseHeader().
   size_t length() const { return length_; }
   const uint8_t* start() const { return start_; }
   const uint8_t* end() const { return end_; }
 
  protected:
   Disassembler(const void* start, size_t length);
 
   bool Good();
   bool Bad(const char *reason);
 
   // Returns true if the array lies within our memory region.
   bool IsArrayInBounds(size_t offset, size_t elements, size_t element_size) {
     return offset <= length() && elements <= (length() - offset) / element_size;
   }
 
+  // Computes and stores all Labels before scanning program bytes.
+  void PrecomputeLabels(AssemblyProgram* program);
+
   // Reduce the length of the image in memory. Does not actually free
   // (or realloc) any memory. Usually only called via ParseHeader().
   void ReduceLength(size_t reduced_length);
 
  private:
   const char* failure_reason_;
 
   //
   // Basic information that is always valid after construction, although
   // ParseHeader() may shorten |length_| if the executable is shorter than the
   // total data.
   //
   size_t length_;         // In current memory.
   const uint8_t* start_;  // In current memory, base for 'file offsets'.
   const uint8_t* end_;    // In current memory.
 
   DISALLOW_COPY_AND_ASSIGN(Disassembler);
 };
 
 }  // namespace courgette
 
 #endif  // COURGETTE_DISASSEMBLER_H_