Subzero: Fix build problem against LLVM trunk.

pnacl-llvm/StreamingMemoryObject.cpp

+//===- StreamingMemoryObject.cpp - Streamable data interface -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/StreamingMemoryObject.h"
+#include <cassert>
+#include <cstddef>
+#include <cstring>
+using namespace llvm;
+
+namespace {
+
+class RawMemoryObject : public MemoryObject {
+public:
+  RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
+    FirstChar(Start), LastChar(End) {
+    assert(LastChar >= FirstChar && "Invalid start/end range");
+  }
+
+  uint64_t getExtent() const override {
+    return LastChar - FirstChar;
+  }
+  uint64_t readBytes(uint8_t *Buf, uint64_t Size,
+                     uint64_t Address) const override;
+  const uint8_t *getPointer(uint64_t address, uint64_t size) const override;
+  bool isValidAddress(uint64_t address) const override {
+    return validAddress(address);
+  }
+
+private:
+  const uint8_t* const FirstChar;
+  const uint8_t* const LastChar;
+
+  // These are implemented as inline functions here to avoid multiple virtual
+  // calls per public function
+  bool validAddress(uint64_t address) const {
+    return static_cast<std::ptrdiff_t>(address) < LastChar - FirstChar;
+  }
+
+  RawMemoryObject(const RawMemoryObject&) = delete;
+  void operator=(const RawMemoryObject&) = delete;
+};
+
+uint64_t RawMemoryObject::readBytes(uint8_t *Buf, uint64_t Size,
+                                    uint64_t Address) const {
+  uint64_t BufferSize = LastChar - FirstChar;
+  if (Address >= BufferSize)
+    return 0;
+
+  uint64_t End = Address + Size;
+  if (End > BufferSize)
+    End = BufferSize;
+
+  assert(static_cast<int64_t>(End - Address) >= 0);
+  Size = End - Address;
+  memcpy(Buf, Address + FirstChar, Size);
+  return Size;
+}
+
+const uint8_t *RawMemoryObject::getPointer(uint64_t address,
+                                           uint64_t size) const {
+  return FirstChar + address;
+}
+} // anonymous namespace
+
+namespace llvm {
+// If the bitcode has a header, then its size is known, and we don't have to
+// block until we actually want to read it.
+bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
+  if (ObjectSize && address < ObjectSize) return true;
+  return fetchToPos(address);
+}
+
+uint64_t StreamingMemoryObject::getExtent() const {
+  if (ObjectSize) return ObjectSize;
+  size_t pos = BytesRead + kChunkSize;
+  // keep fetching until we run out of bytes
+  while (fetchToPos(pos)) pos += kChunkSize;
+  return ObjectSize;
+}
+
+uint64_t StreamingMemoryObject::readBytes(uint8_t *Buf, uint64_t Size,
+                                          uint64_t Address) const {
+  fetchToPos(Address + Size - 1);
+  // Note: For wrapped bitcode files will set ObjectSize after the
+  // first call to fetchToPos. In such cases, ObjectSize can be
+  // smaller than BytesRead.
+  size_t MaxAddress =
+      (ObjectSize && ObjectSize < BytesRead) ? ObjectSize : BytesRead;
+  if (Address >= MaxAddress)
+    return 0;
+
+  uint64_t End = Address + Size;
+  if (End > MaxAddress)
+    End = MaxAddress;
+  assert(End >= Address);
+  Size = End - Address;
+  memcpy(Buf, &Bytes[Address + BytesSkipped], Size);
+  return Size;
+}
+
+const uint8_t *StreamingMemoryObject::getPointer(uint64_t Address,
+                                                 uint64_t Size) const {
+  fetchToPos(Address + Size - 1);
+  return &Bytes[Address + BytesSkipped];
+}
+
+bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
+  if (BytesRead < s) return true;
+  BytesSkipped = s;
+  BytesRead -= s;
+  return false;
+}
+
+void StreamingMemoryObject::setKnownObjectSize(size_t size) {
+  ObjectSize = size;
+  Bytes.reserve(size);
+  if (ObjectSize <= BytesRead)
+    EOFReached = true;
+}
+
+MemoryObject *getNonStreamedMemoryObject(const unsigned char *Start,
+                                         const unsigned char *End) {
+  return new RawMemoryObject(Start, End);
+}
+
+StreamingMemoryObject::StreamingMemoryObject(
+    std::unique_ptr<DataStreamer> Streamer)
+    : Bytes(kChunkSize), Streamer(std::move(Streamer)), BytesRead(0),
+      BytesSkipped(0), ObjectSize(0), EOFReached(false) {
+  BytesRead = this->Streamer->GetBytes(&Bytes[0], kChunkSize);
+}
+}