StreamableMemoryObject.cpp revision 239462 
1//===- StreamableMemoryObject.cpp - Streamable data interface -------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Support/StreamableMemoryObject.h"
11#include <cassert>
12#include <cstring>
13
14
15using namespace llvm;
16
17namespace {
18
19class RawMemoryObject : public StreamableMemoryObject {
20public:
21  RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
22    FirstChar(Start), LastChar(End) {
23    assert(LastChar >= FirstChar && "Invalid start/end range");
24  }
25
26  virtual uint64_t getBase() const { return 0; }
27  virtual uint64_t getExtent() const { return LastChar - FirstChar; }
28  virtual int readByte(uint64_t address, uint8_t* ptr) const;
29  virtual int readBytes(uint64_t address,
30                        uint64_t size,
31                        uint8_t* buf,
32                        uint64_t* copied) const;
33  virtual const uint8_t *getPointer(uint64_t address, uint64_t size) const;
34  virtual bool isValidAddress(uint64_t address) const {
35    return validAddress(address);
36  }
37  virtual bool isObjectEnd(uint64_t address) const {return objectEnd(address);}
38
39private:
40  const uint8_t* const FirstChar;
41  const uint8_t* const LastChar;
42
43  // These are implemented as inline functions here to avoid multiple virtual
44  // calls per public function
45  bool validAddress(uint64_t address) const {
46    return static_cast<ptrdiff_t>(address) < LastChar - FirstChar;
47  }
48  bool objectEnd(uint64_t address) const {
49    return static_cast<ptrdiff_t>(address) == LastChar - FirstChar;
50  }
51
52  RawMemoryObject(const RawMemoryObject&);  // DO NOT IMPLEMENT
53  void operator=(const RawMemoryObject&);  // DO NOT IMPLEMENT
54};
55
56int RawMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
57  if (!validAddress(address)) return -1;
58  *ptr = *((uint8_t *)(uintptr_t)(address + FirstChar));
59  return 0;
60}
61
62int RawMemoryObject::readBytes(uint64_t address,
63                               uint64_t size,
64                               uint8_t* buf,
65                               uint64_t* copied) const {
66  if (!validAddress(address) || !validAddress(address + size - 1)) return -1;
67  memcpy(buf, (uint8_t *)(uintptr_t)(address + FirstChar), size);
68  if (copied) *copied = size;
69  return size;
70}
71
72const uint8_t *RawMemoryObject::getPointer(uint64_t address,
73                                           uint64_t size) const {
74  return FirstChar + address;
75}
76} // anonymous namespace
77
78namespace llvm {
79// If the bitcode has a header, then its size is known, and we don't have to
80// block until we actually want to read it.
81bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
82  if (ObjectSize && address < ObjectSize) return true;
83    return fetchToPos(address);
84}
85
86bool StreamingMemoryObject::isObjectEnd(uint64_t address) const {
87  if (ObjectSize) return address == ObjectSize;
88  fetchToPos(address);
89  return address == ObjectSize && address != 0;
90}
91
92uint64_t StreamingMemoryObject::getExtent() const {
93  if (ObjectSize) return ObjectSize;
94  size_t pos = BytesRead + kChunkSize;
95  // keep fetching until we run out of bytes
96  while (fetchToPos(pos)) pos += kChunkSize;
97  return ObjectSize;
98}
99
100int StreamingMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
101  if (!fetchToPos(address)) return -1;
102  *ptr = Bytes[address + BytesSkipped];
103  return 0;
104}
105
106int StreamingMemoryObject::readBytes(uint64_t address,
107                                     uint64_t size,
108                                     uint8_t* buf,
109                                     uint64_t* copied) const {
110  if (!fetchToPos(address + size - 1)) return -1;
111  memcpy(buf, &Bytes[address + BytesSkipped], size);
112  if (copied) *copied = size;
113  return 0;
114}
115
116bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
117  if (BytesRead < s) return true;
118  BytesSkipped = s;
119  BytesRead -= s;
120  return false;
121}
122
123void StreamingMemoryObject::setKnownObjectSize(size_t size) {
124  ObjectSize = size;
125  Bytes.reserve(size);
126}
127
128StreamableMemoryObject *getNonStreamedMemoryObject(
129    const unsigned char *Start, const unsigned char *End) {
130  return new RawMemoryObject(Start, End);
131}
132
133StreamableMemoryObject::~StreamableMemoryObject() { }
134
135StreamingMemoryObject::StreamingMemoryObject(DataStreamer *streamer) :
136  Bytes(kChunkSize), Streamer(streamer), BytesRead(0), BytesSkipped(0),
137  ObjectSize(0), EOFReached(false) {
138  BytesRead = streamer->GetBytes(&Bytes[0], kChunkSize);
139}
140}
141