89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
//===--- llvm/Support/DataStream.cpp - Lazy streamed data -----------------===//
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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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//
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// This file implements DataStreamer, which fetches bytes of Data from
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// a stream source. It provides support for streaming (lazy reading) of
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// bitcode. An example implementation of streaming from a file or stdin
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// is included.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/DataStream.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/Program.h"
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#include <string>
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#include <system_error>
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#if !defined(_MSC_VER) && !defined(__MINGW32__)
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#include <unistd.h>
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#else
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#include <io.h>
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#endif
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using namespace llvm;
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#define DEBUG_TYPE "Data-stream"
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// Interface goals:
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// * StreamingMemoryObject doesn't care about complexities like using
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// threads/async callbacks to actually overlap download+compile
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// * Don't want to duplicate Data in memory
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// * Don't need to know total Data len in advance
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// Non-goals:
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// StreamingMemoryObject already has random access so this interface only does
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// in-order streaming (no arbitrary seeking, else we'd have to buffer all the
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// Data here in addition to MemoryObject). This also means that if we want
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// to be able to to free Data, BitstreamBytes/BitcodeReader will implement it
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STATISTIC(NumStreamFetches, "Number of calls to Data stream fetch");
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namespace llvm {
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DataStreamer::~DataStreamer() {}
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}
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namespace {
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// Very simple stream backed by a file. Mostly useful for stdin and debugging;
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// actual file access is probably still best done with mmap.
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class DataFileStreamer : public DataStreamer {
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int Fd;
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public:
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DataFileStreamer() : Fd(0) {}
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~DataFileStreamer() override { close(Fd); }
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size_t GetBytes(unsigned char *buf, size_t len) override {
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NumStreamFetches++;
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return read(Fd, buf, len);
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}
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std::error_code OpenFile(const std::string &Filename) {
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if (Filename == "-") {
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Fd = 0;
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sys::ChangeStdinToBinary();
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return std::error_code();
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}
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return sys::fs::openFileForRead(Filename, Fd);
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}
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};
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}
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namespace llvm {
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DataStreamer *getDataFileStreamer(const std::string &Filename,
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std::string *StrError) {
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DataFileStreamer *s = new DataFileStreamer();
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if (std::error_code e = s->OpenFile(Filename)) {
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*StrError = std::string("Could not open ") + Filename + ": " +
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e.message() + "\n";
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return nullptr;
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}
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return s;
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}
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}
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