c11bd4229c
The reading of 64 bit values could still be optimized, but at least this cuts down on the number of virtual calls to fetch more data. llvm-svn: 221865
128 lines
3.7 KiB
C++
128 lines
3.7 KiB
C++
//===- StreamingMemoryObject.cpp - Streamable data interface -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/StreamingMemoryObject.h"
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#include "llvm/Support/Compiler.h"
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#include <cassert>
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#include <cstddef>
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#include <cstring>
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using namespace llvm;
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namespace {
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class RawMemoryObject : public MemoryObject {
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public:
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RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
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FirstChar(Start), LastChar(End) {
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assert(LastChar >= FirstChar && "Invalid start/end range");
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}
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uint64_t getExtent() const override {
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return LastChar - FirstChar;
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}
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uint64_t readBytes(uint8_t *Buf, uint64_t Size,
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uint64_t Address) const override;
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const uint8_t *getPointer(uint64_t address, uint64_t size) const override;
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bool isValidAddress(uint64_t address) const override {
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return validAddress(address);
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}
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private:
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const uint8_t* const FirstChar;
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const uint8_t* const LastChar;
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// These are implemented as inline functions here to avoid multiple virtual
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// calls per public function
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bool validAddress(uint64_t address) const {
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return static_cast<std::ptrdiff_t>(address) < LastChar - FirstChar;
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}
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RawMemoryObject(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
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void operator=(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
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};
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uint64_t RawMemoryObject::readBytes(uint8_t *Buf, uint64_t Size,
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uint64_t Address) const {
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uint64_t BufferSize = LastChar - FirstChar;
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if (Address >= BufferSize)
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return 0;
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uint64_t End = Address + Size;
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if (End > BufferSize)
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End = BufferSize;
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Size = End - Address;
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assert(Size >= 0);
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memcpy(Buf, (uint8_t *)(Address + FirstChar), Size);
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return Size;
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}
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const uint8_t *RawMemoryObject::getPointer(uint64_t address,
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uint64_t size) const {
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return FirstChar + address;
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}
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} // anonymous namespace
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namespace llvm {
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// If the bitcode has a header, then its size is known, and we don't have to
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// block until we actually want to read it.
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bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
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if (ObjectSize && address < ObjectSize) return true;
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return fetchToPos(address);
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}
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uint64_t StreamingMemoryObject::getExtent() const {
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if (ObjectSize) return ObjectSize;
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size_t pos = BytesRead + kChunkSize;
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// keep fetching until we run out of bytes
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while (fetchToPos(pos)) pos += kChunkSize;
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return ObjectSize;
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}
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uint64_t StreamingMemoryObject::readBytes(uint8_t *Buf, uint64_t Size,
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uint64_t Address) const {
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fetchToPos(Address + Size - 1);
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if (Address >= BytesRead)
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return 0;
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uint64_t End = Address + Size;
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if (End > BytesRead)
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End = BytesRead;
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Size = End - Address;
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assert(Size >= 0);
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memcpy(Buf, &Bytes[Address + BytesSkipped], Size);
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return Size;
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}
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bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
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if (BytesRead < s) return true;
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BytesSkipped = s;
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BytesRead -= s;
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return false;
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}
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void StreamingMemoryObject::setKnownObjectSize(size_t size) {
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ObjectSize = size;
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Bytes.reserve(size);
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}
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MemoryObject *getNonStreamedMemoryObject(const unsigned char *Start,
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const unsigned char *End) {
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return new RawMemoryObject(Start, End);
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}
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StreamingMemoryObject::StreamingMemoryObject(DataStreamer *streamer) :
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Bytes(kChunkSize), Streamer(streamer), BytesRead(0), BytesSkipped(0),
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ObjectSize(0), EOFReached(false) {
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BytesRead = streamer->GetBytes(&Bytes[0], kChunkSize);
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}
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}
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