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 "llvm/Support/Compiler.h"
12 #include <cassert>
13 #include <cstddef>
14 #include <cstring>
15
16
17 using namespace llvm;
18
19 namespace {
20
21 class RawMemoryObject : public StreamableMemoryObject {
22 public:
RawMemoryObject(const unsigned char * Start,const unsigned char * End)23 RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
24 FirstChar(Start), LastChar(End) {
25 assert(LastChar >= FirstChar && "Invalid start/end range");
26 }
27
getBase() const28 uint64_t getBase() const override { return 0; }
getExtent() const29 uint64_t getExtent() const override {
30 return LastChar - FirstChar;
31 }
32 int readByte(uint64_t address, uint8_t* ptr) const override;
33 int readBytes(uint64_t address, uint64_t size,
34 uint8_t *buf) const override;
35 const uint8_t *getPointer(uint64_t address, uint64_t size) const override;
isValidAddress(uint64_t address) const36 bool isValidAddress(uint64_t address) const override {
37 return validAddress(address);
38 }
isObjectEnd(uint64_t address) const39 bool isObjectEnd(uint64_t address) const override {
40 return objectEnd(address);
41 }
42
43 private:
44 const uint8_t* const FirstChar;
45 const uint8_t* const LastChar;
46
47 // These are implemented as inline functions here to avoid multiple virtual
48 // calls per public function
validAddress(uint64_t address) const49 bool validAddress(uint64_t address) const {
50 return static_cast<std::ptrdiff_t>(address) < LastChar - FirstChar;
51 }
objectEnd(uint64_t address) const52 bool objectEnd(uint64_t address) const {
53 return static_cast<std::ptrdiff_t>(address) == LastChar - FirstChar;
54 }
55
56 RawMemoryObject(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
57 void operator=(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
58 };
59
readByte(uint64_t address,uint8_t * ptr) const60 int RawMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
61 if (!validAddress(address)) return -1;
62 *ptr = *((uint8_t *)(uintptr_t)(address + FirstChar));
63 return 0;
64 }
65
readBytes(uint64_t address,uint64_t size,uint8_t * buf) const66 int RawMemoryObject::readBytes(uint64_t address,
67 uint64_t size,
68 uint8_t *buf) const {
69 if (!validAddress(address) || !validAddress(address + size - 1)) return -1;
70 memcpy(buf, (uint8_t *)(uintptr_t)(address + FirstChar), size);
71 return size;
72 }
73
getPointer(uint64_t address,uint64_t size) const74 const uint8_t *RawMemoryObject::getPointer(uint64_t address,
75 uint64_t size) const {
76 return FirstChar + address;
77 }
78 } // anonymous namespace
79
80 namespace llvm {
81 // If the bitcode has a header, then its size is known, and we don't have to
82 // block until we actually want to read it.
isValidAddress(uint64_t address) const83 bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
84 if (ObjectSize && address < ObjectSize) return true;
85 return fetchToPos(address);
86 }
87
isObjectEnd(uint64_t address) const88 bool StreamingMemoryObject::isObjectEnd(uint64_t address) const {
89 if (ObjectSize) return address == ObjectSize;
90 fetchToPos(address);
91 return address == ObjectSize && address != 0;
92 }
93
getExtent() const94 uint64_t StreamingMemoryObject::getExtent() const {
95 if (ObjectSize) return ObjectSize;
96 size_t pos = BytesRead + kChunkSize;
97 // keep fetching until we run out of bytes
98 while (fetchToPos(pos)) pos += kChunkSize;
99 return ObjectSize;
100 }
101
readByte(uint64_t address,uint8_t * ptr) const102 int StreamingMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
103 if (!fetchToPos(address)) return -1;
104 *ptr = Bytes[address + BytesSkipped];
105 return 0;
106 }
107
readBytes(uint64_t address,uint64_t size,uint8_t * buf) const108 int StreamingMemoryObject::readBytes(uint64_t address,
109 uint64_t size,
110 uint8_t *buf) const {
111 if (!fetchToPos(address + size - 1)) return -1;
112 memcpy(buf, &Bytes[address + BytesSkipped], size);
113 return 0;
114 }
115
dropLeadingBytes(size_t s)116 bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
117 if (BytesRead < s) return true;
118 BytesSkipped = s;
119 BytesRead -= s;
120 return false;
121 }
122
setKnownObjectSize(size_t size)123 void StreamingMemoryObject::setKnownObjectSize(size_t size) {
124 ObjectSize = size;
125 Bytes.reserve(size);
126 }
127
getNonStreamedMemoryObject(const unsigned char * Start,const unsigned char * End)128 StreamableMemoryObject *getNonStreamedMemoryObject(
129 const unsigned char *Start, const unsigned char *End) {
130 return new RawMemoryObject(Start, End);
131 }
132
~StreamableMemoryObject()133 StreamableMemoryObject::~StreamableMemoryObject() { }
134
StreamingMemoryObject(DataStreamer * streamer)135 StreamingMemoryObject::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