clang 19.0.0git
Go to the documentation of this file.
1//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
9// This file implements the ScratchBuffer interface.
15#include "llvm/Support/MemoryBuffer.h"
16#include <cstring>
17using namespace clang;
19// ScratchBufSize - The size of each chunk of scratch memory. Slightly less
20//than a page, almost certainly enough for anything. :)
21static const unsigned ScratchBufSize = 4060;
24 : SourceMgr(SM), CurBuffer(nullptr) {
25 // Set BytesUsed so that the first call to getToken will require an alloc.
26 BytesUsed = ScratchBufSize;
29/// getToken - Splat the specified text into a temporary MemoryBuffer and
30/// return a SourceLocation that refers to the token. This is just like the
31/// method below, but returns a location that indicates the physloc of the
32/// token.
33SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
34 const char *&DestPtr) {
35 if (BytesUsed+Len+2 > ScratchBufSize)
36 AllocScratchBuffer(Len+2);
37 else {
38 // Clear out the source line cache if it's already been computed.
39 // FIXME: Allow this to be incrementally extended.
40 SourceMgr.getSLocEntry(SourceMgr.getFileID(BufferStartLoc))
41 .getFile()
44 }
46 // Prefix the token with a \n, so that it looks like it is the first thing on
47 // its own virtual line in caret diagnostics.
48 CurBuffer[BytesUsed++] = '\n';
50 // Return a pointer to the character data.
51 DestPtr = CurBuffer+BytesUsed;
53 // Copy the token data into the buffer.
54 memcpy(CurBuffer+BytesUsed, Buf, Len);
56 // Remember that we used these bytes.
57 BytesUsed += Len+1;
59 // Add a NUL terminator to the token. This keeps the tokens separated, in
60 // case they get relexed, and puts them on their own virtual lines in case a
61 // diagnostic points to one.
62 CurBuffer[BytesUsed-1] = '\0';
64 return BufferStartLoc.getLocWithOffset(BytesUsed-Len-1);
67void ScratchBuffer::AllocScratchBuffer(unsigned RequestLen) {
68 // Only pay attention to the requested length if it is larger than our default
69 // page size. If it is, we allocate an entire chunk for it. This is to
70 // support gigantic tokens, which almost certainly won't happen. :)
71 if (RequestLen < ScratchBufSize)
72 RequestLen = ScratchBufSize;
74 // Get scratch buffer. Zero-initialize it so it can be dumped into a PCH file
75 // deterministically.
76 std::unique_ptr<llvm::WritableMemoryBuffer> OwnBuf =
77 llvm::WritableMemoryBuffer::getNewMemBuffer(RequestLen,
78 "<scratch space>");
79 CurBuffer = OwnBuf->getBufferStart();
80 FileID FID = SourceMgr.createFileID(std::move(OwnBuf));
81 BufferStartLoc = SourceMgr.getLocForStartOfFile(FID);
82 BytesUsed = 0;
#define SM(sm)
Definition: Cuda.cpp:83
static const unsigned ScratchBufSize
Defines the SourceManager interface.
__DEVICE__ void * memcpy(void *__a, const void *__b, size_t __c)
An opaque identifier used by SourceManager which refers to a source file (MemoryBuffer) along with it...
SourceLocation getToken(const char *Buf, unsigned Len, const char *&DestPtr)
getToken - Splat the specified text into a temporary MemoryBuffer and return a SourceLocation that re...
ScratchBuffer(SourceManager &SM)
Encodes a location in the source.
SourceLocation getLocWithOffset(IntTy Offset) const
Return a source location with the specified offset from this SourceLocation.
This class handles loading and caching of source files into memory.
FileID getFileID(SourceLocation SpellingLoc) const
Return the FileID for a SourceLocation.
FileID createFileID(FileEntryRef SourceFile, SourceLocation IncludePos, SrcMgr::CharacteristicKind FileCharacter, int LoadedID=0, SourceLocation::UIntTy LoadedOffset=0)
Create a new FileID that represents the specified file being #included from the specified IncludePosi...
SourceLocation getLocForStartOfFile(FileID FID) const
Return the source location corresponding to the first byte of the specified file.
const SrcMgr::SLocEntry & getSLocEntry(FileID FID, bool *Invalid=nullptr) const
LineOffsetMapping SourceLineCache
A bump pointer allocated array of offsets for each source line.
const ContentCache & getContentCache() const
Mapping of line offsets into a source file.
const FileInfo & getFile() const
The JSON file list parser is used to communicate input to InstallAPI.