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391 lines
13 KiB
C++
391 lines
13 KiB
C++
//===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
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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/Bitcode/BitstreamReader.h"
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#include "llvm/ADT/StringRef.h"
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#include <cassert>
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#include <string>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// BitstreamCursor implementation
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//===----------------------------------------------------------------------===//
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/// EnterSubBlock - Having read the ENTER_SUBBLOCK abbrevid, enter
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/// the block, and return true if the block has an error.
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bool BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
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// Save the current block's state on BlockScope.
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BlockScope.push_back(Block(CurCodeSize));
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BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
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// Add the abbrevs specific to this block to the CurAbbrevs list.
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if (BlockInfo) {
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if (const BitstreamBlockInfo::BlockInfo *Info =
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BlockInfo->getBlockInfo(BlockID)) {
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CurAbbrevs.insert(CurAbbrevs.end(), Info->Abbrevs.begin(),
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Info->Abbrevs.end());
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}
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}
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// Get the codesize of this block.
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CurCodeSize = ReadVBR(bitc::CodeLenWidth);
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// We can't read more than MaxChunkSize at a time
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if (CurCodeSize > MaxChunkSize)
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return true;
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SkipToFourByteBoundary();
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unsigned NumWords = Read(bitc::BlockSizeWidth);
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if (NumWordsP) *NumWordsP = NumWords;
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// Validate that this block is sane.
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return CurCodeSize == 0 || AtEndOfStream();
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}
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static uint64_t readAbbreviatedField(BitstreamCursor &Cursor,
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const BitCodeAbbrevOp &Op) {
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assert(!Op.isLiteral() && "Not to be used with literals!");
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// Decode the value as we are commanded.
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switch (Op.getEncoding()) {
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case BitCodeAbbrevOp::Array:
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case BitCodeAbbrevOp::Blob:
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llvm_unreachable("Should not reach here");
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case BitCodeAbbrevOp::Fixed:
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assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
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return Cursor.Read((unsigned)Op.getEncodingData());
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case BitCodeAbbrevOp::VBR:
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assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
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return Cursor.ReadVBR64((unsigned)Op.getEncodingData());
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case BitCodeAbbrevOp::Char6:
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return BitCodeAbbrevOp::DecodeChar6(Cursor.Read(6));
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}
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llvm_unreachable("invalid abbreviation encoding");
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}
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static void skipAbbreviatedField(BitstreamCursor &Cursor,
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const BitCodeAbbrevOp &Op) {
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assert(!Op.isLiteral() && "Not to be used with literals!");
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// Decode the value as we are commanded.
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switch (Op.getEncoding()) {
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case BitCodeAbbrevOp::Array:
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case BitCodeAbbrevOp::Blob:
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llvm_unreachable("Should not reach here");
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case BitCodeAbbrevOp::Fixed:
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assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
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Cursor.Read((unsigned)Op.getEncodingData());
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break;
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case BitCodeAbbrevOp::VBR:
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assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
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Cursor.ReadVBR64((unsigned)Op.getEncodingData());
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break;
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case BitCodeAbbrevOp::Char6:
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Cursor.Read(6);
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break;
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}
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}
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/// skipRecord - Read the current record and discard it.
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unsigned BitstreamCursor::skipRecord(unsigned AbbrevID) {
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// Skip unabbreviated records by reading past their entries.
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if (AbbrevID == bitc::UNABBREV_RECORD) {
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unsigned Code = ReadVBR(6);
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unsigned NumElts = ReadVBR(6);
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for (unsigned i = 0; i != NumElts; ++i)
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(void)ReadVBR64(6);
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return Code;
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}
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const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
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const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
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unsigned Code;
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if (CodeOp.isLiteral())
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Code = CodeOp.getLiteralValue();
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else {
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if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
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CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
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report_fatal_error("Abbreviation starts with an Array or a Blob");
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Code = readAbbreviatedField(*this, CodeOp);
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}
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for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i < e; ++i) {
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const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
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if (Op.isLiteral())
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continue;
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if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
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Op.getEncoding() != BitCodeAbbrevOp::Blob) {
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skipAbbreviatedField(*this, Op);
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continue;
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}
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if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
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// Array case. Read the number of elements as a vbr6.
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unsigned NumElts = ReadVBR(6);
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// Get the element encoding.
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assert(i+2 == e && "array op not second to last?");
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const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
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// Read all the elements.
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// Decode the value as we are commanded.
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switch (EltEnc.getEncoding()) {
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default:
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report_fatal_error("Array element type can't be an Array or a Blob");
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case BitCodeAbbrevOp::Fixed:
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assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize);
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JumpToBit(GetCurrentBitNo() + NumElts * EltEnc.getEncodingData());
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break;
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case BitCodeAbbrevOp::VBR:
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assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize);
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for (; NumElts; --NumElts)
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ReadVBR64((unsigned)EltEnc.getEncodingData());
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break;
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case BitCodeAbbrevOp::Char6:
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JumpToBit(GetCurrentBitNo() + NumElts * 6);
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break;
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}
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continue;
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}
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assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
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// Blob case. Read the number of bytes as a vbr6.
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unsigned NumElts = ReadVBR(6);
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SkipToFourByteBoundary(); // 32-bit alignment
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// Figure out where the end of this blob will be including tail padding.
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size_t NewEnd = GetCurrentBitNo()+((NumElts+3)&~3)*8;
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// If this would read off the end of the bitcode file, just set the
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// record to empty and return.
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if (!canSkipToPos(NewEnd/8)) {
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skipToEnd();
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break;
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}
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// Skip over the blob.
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JumpToBit(NewEnd);
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}
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return Code;
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}
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unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
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SmallVectorImpl<uint64_t> &Vals,
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StringRef *Blob) {
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if (AbbrevID == bitc::UNABBREV_RECORD) {
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unsigned Code = ReadVBR(6);
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unsigned NumElts = ReadVBR(6);
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for (unsigned i = 0; i != NumElts; ++i)
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Vals.push_back(ReadVBR64(6));
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return Code;
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}
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const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
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// Read the record code first.
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assert(Abbv->getNumOperandInfos() != 0 && "no record code in abbreviation?");
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const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
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unsigned Code;
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if (CodeOp.isLiteral())
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Code = CodeOp.getLiteralValue();
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else {
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if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
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CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
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report_fatal_error("Abbreviation starts with an Array or a Blob");
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Code = readAbbreviatedField(*this, CodeOp);
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}
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for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
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const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
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if (Op.isLiteral()) {
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Vals.push_back(Op.getLiteralValue());
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continue;
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}
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if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
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Op.getEncoding() != BitCodeAbbrevOp::Blob) {
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Vals.push_back(readAbbreviatedField(*this, Op));
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continue;
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}
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if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
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// Array case. Read the number of elements as a vbr6.
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unsigned NumElts = ReadVBR(6);
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// Get the element encoding.
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if (i + 2 != e)
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report_fatal_error("Array op not second to last");
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const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
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if (!EltEnc.isEncoding())
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report_fatal_error(
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"Array element type has to be an encoding of a type");
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// Read all the elements.
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switch (EltEnc.getEncoding()) {
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default:
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report_fatal_error("Array element type can't be an Array or a Blob");
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case BitCodeAbbrevOp::Fixed:
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for (; NumElts; --NumElts)
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Vals.push_back(Read((unsigned)EltEnc.getEncodingData()));
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break;
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case BitCodeAbbrevOp::VBR:
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for (; NumElts; --NumElts)
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Vals.push_back(ReadVBR64((unsigned)EltEnc.getEncodingData()));
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break;
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case BitCodeAbbrevOp::Char6:
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for (; NumElts; --NumElts)
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Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
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}
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continue;
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}
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assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
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// Blob case. Read the number of bytes as a vbr6.
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unsigned NumElts = ReadVBR(6);
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SkipToFourByteBoundary(); // 32-bit alignment
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// Figure out where the end of this blob will be including tail padding.
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size_t CurBitPos = GetCurrentBitNo();
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size_t NewEnd = CurBitPos+((NumElts+3)&~3)*8;
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// If this would read off the end of the bitcode file, just set the
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// record to empty and return.
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if (!canSkipToPos(NewEnd/8)) {
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Vals.append(NumElts, 0);
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skipToEnd();
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break;
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}
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// Otherwise, inform the streamer that we need these bytes in memory. Skip
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// over tail padding first, in case jumping to NewEnd invalidates the Blob
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// pointer.
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JumpToBit(NewEnd);
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const char *Ptr = (const char *)getPointerToBit(CurBitPos, NumElts);
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// If we can return a reference to the data, do so to avoid copying it.
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if (Blob) {
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*Blob = StringRef(Ptr, NumElts);
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} else {
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// Otherwise, unpack into Vals with zero extension.
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for (; NumElts; --NumElts)
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Vals.push_back((unsigned char)*Ptr++);
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}
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}
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return Code;
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}
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void BitstreamCursor::ReadAbbrevRecord() {
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auto Abbv = std::make_shared<BitCodeAbbrev>();
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unsigned NumOpInfo = ReadVBR(5);
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for (unsigned i = 0; i != NumOpInfo; ++i) {
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bool IsLiteral = Read(1);
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if (IsLiteral) {
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Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
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continue;
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}
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BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
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if (BitCodeAbbrevOp::hasEncodingData(E)) {
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uint64_t Data = ReadVBR64(5);
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// As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
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// and vbr(0) as a literal zero. This is decoded the same way, and avoids
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// a slow path in Read() to have to handle reading zero bits.
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if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
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Data == 0) {
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Abbv->Add(BitCodeAbbrevOp(0));
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continue;
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}
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if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
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Data > MaxChunkSize)
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report_fatal_error(
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"Fixed or VBR abbrev record with size > MaxChunkData");
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Abbv->Add(BitCodeAbbrevOp(E, Data));
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} else
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Abbv->Add(BitCodeAbbrevOp(E));
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}
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if (Abbv->getNumOperandInfos() == 0)
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report_fatal_error("Abbrev record with no operands");
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CurAbbrevs.push_back(std::move(Abbv));
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}
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Optional<BitstreamBlockInfo>
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BitstreamCursor::ReadBlockInfoBlock(bool ReadBlockInfoNames) {
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if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return None;
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BitstreamBlockInfo NewBlockInfo;
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SmallVector<uint64_t, 64> Record;
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BitstreamBlockInfo::BlockInfo *CurBlockInfo = nullptr;
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// Read all the records for this module.
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while (true) {
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BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
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switch (Entry.Kind) {
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case llvm::BitstreamEntry::SubBlock: // Handled for us already.
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case llvm::BitstreamEntry::Error:
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return None;
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case llvm::BitstreamEntry::EndBlock:
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return std::move(NewBlockInfo);
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case llvm::BitstreamEntry::Record:
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// The interesting case.
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break;
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}
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// Read abbrev records, associate them with CurBID.
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if (Entry.ID == bitc::DEFINE_ABBREV) {
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if (!CurBlockInfo) return None;
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ReadAbbrevRecord();
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// ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
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// appropriate BlockInfo.
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CurBlockInfo->Abbrevs.push_back(std::move(CurAbbrevs.back()));
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CurAbbrevs.pop_back();
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continue;
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}
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// Read a record.
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Record.clear();
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switch (readRecord(Entry.ID, Record)) {
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default: break; // Default behavior, ignore unknown content.
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case bitc::BLOCKINFO_CODE_SETBID:
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if (Record.size() < 1) return None;
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CurBlockInfo = &NewBlockInfo.getOrCreateBlockInfo((unsigned)Record[0]);
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break;
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case bitc::BLOCKINFO_CODE_BLOCKNAME: {
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if (!CurBlockInfo) return None;
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if (!ReadBlockInfoNames)
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break; // Ignore name.
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std::string Name;
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for (unsigned i = 0, e = Record.size(); i != e; ++i)
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Name += (char)Record[i];
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CurBlockInfo->Name = Name;
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break;
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}
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case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
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if (!CurBlockInfo) return None;
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if (!ReadBlockInfoNames)
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break; // Ignore name.
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std::string Name;
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for (unsigned i = 1, e = Record.size(); i != e; ++i)
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Name += (char)Record[i];
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CurBlockInfo->RecordNames.push_back(std::make_pair((unsigned)Record[0],
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Name));
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break;
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}
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}
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}
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}
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