Coverage Report

Created: 2020-02-25 14:32

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/Lex/ScratchBuffer.cpp
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//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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//  This file implements the ScratchBuffer interface.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Lex/ScratchBuffer.h"
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#include "clang/Basic/SourceManager.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include <cstring>
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using namespace clang;
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// ScratchBufSize - The size of each chunk of scratch memory.  Slightly less
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//than a page, almost certainly enough for anything. :)
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static const unsigned ScratchBufSize = 4060;
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ScratchBuffer::ScratchBuffer(SourceManager &SM)
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    : SourceMgr(SM), CurBuffer(nullptr) {
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  // Set BytesUsed so that the first call to getToken will require an alloc.
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  BytesUsed = ScratchBufSize;
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}
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/// getToken - Splat the specified text into a temporary MemoryBuffer and
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/// return a SourceLocation that refers to the token.  This is just like the
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/// method below, but returns a location that indicates the physloc of the
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/// token.
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SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
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                                       const char *&DestPtr) {
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  if (BytesUsed+Len+2 > ScratchBufSize)
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    AllocScratchBuffer(Len+2);
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  else {
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    // Clear out the source line cache if it's already been computed.
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    // FIXME: Allow this to be incrementally extended.
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    auto *ContentCache = const_cast<SrcMgr::ContentCache *>(
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        SourceMgr.getSLocEntry(SourceMgr.getFileID(BufferStartLoc))
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                 .getFile().getContentCache());
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    ContentCache->SourceLineCache = nullptr;
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  }
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  // Prefix the token with a \n, so that it looks like it is the first thing on
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  // its own virtual line in caret diagnostics.
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  CurBuffer[BytesUsed++] = '\n';
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  // Return a pointer to the character data.
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  DestPtr = CurBuffer+BytesUsed;
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  // Copy the token data into the buffer.
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  memcpy(CurBuffer+BytesUsed, Buf, Len);
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  // Remember that we used these bytes.
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  BytesUsed += Len+1;
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  // Add a NUL terminator to the token.  This keeps the tokens separated, in
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  // case they get relexed, and puts them on their own virtual lines in case a
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  // diagnostic points to one.
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  CurBuffer[BytesUsed-1] = '\0';
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  return BufferStartLoc.getLocWithOffset(BytesUsed-Len-1);
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}
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void ScratchBuffer::AllocScratchBuffer(unsigned RequestLen) {
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  // Only pay attention to the requested length if it is larger than our default
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  // page size.  If it is, we allocate an entire chunk for it.  This is to
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  // support gigantic tokens, which almost certainly won't happen. :)
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  if (RequestLen < ScratchBufSize)
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    RequestLen = ScratchBufSize;
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  // Get scratch buffer. Zero-initialize it so it can be dumped into a PCH file
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  // deterministically.
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  std::unique_ptr<llvm::WritableMemoryBuffer> OwnBuf =
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      llvm::WritableMemoryBuffer::getNewMemBuffer(RequestLen,
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                                                  "<scratch space>");
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  CurBuffer = OwnBuf->getBufferStart();
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  FileID FID = SourceMgr.createFileID(std::move(OwnBuf));
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  BufferStartLoc = SourceMgr.getLocForStartOfFile(FID);
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  BytesUsed = 0;
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}