dc5c055fd1
fileid/offset pair, it now contains a bit discriminating between mapped locations and file locations. This separates the tables for macros and files in SourceManager, and allows better separation of concepts in the rest of the compiler. This allows us to have *many* macro instantiations before running out of 'addressing space'. This is also more efficient, because testing whether something is a macro expansion is now a bit test instead of a table lookup (which also used to require having a srcmgr around, now it doesn't). This is fully functional, but there are several refinements and optimizations left. llvm-svn: 40103
72 lines
2.7 KiB
C++
72 lines
2.7 KiB
C++
//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Chris Lattner and is distributed under
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// the University of Illinois Open Source 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 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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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) : SourceMgr(SM), CurBuffer(0) {
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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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FileID = 0;
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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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if (BytesUsed+Len > ScratchBufSize)
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AllocScratchBuffer(Len);
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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;
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assert(BytesUsed-Len < (1 << SourceLocation::FilePosBits) &&
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"Out of range file position!");
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return SourceLocation::getFileLoc(FileID, BytesUsed-Len);
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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. The SourceLoc value
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/// gives a virtual location that the token will appear to be from.
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SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
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SourceLocation SourceLoc) {
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// Map the physloc to the specified sourceloc.
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return SourceMgr.getInstantiationLoc(getToken(Buf, Len), SourceLoc);
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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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llvm::MemoryBuffer *Buf =
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llvm::MemoryBuffer::getNewMemBuffer(RequestLen, "<scratch space>");
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FileID = SourceMgr.createFileIDForMemBuffer(Buf);
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CurBuffer = const_cast<char*>(Buf->getBufferStart());
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BytesUsed = 0;
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}
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