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Nothing fancy, just a simple demonstration parser. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167181 91177308-0d34-0410-b5e6-96231b3b80d8
226 lines
7.1 KiB
C++
226 lines
7.1 KiB
C++
//===-- llvm-mcmarkup.cpp - Parse the MC assembly markup tags -------------===//
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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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// Example simple parser implementation for the MC assembly markup language.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/OwningPtr.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/ManagedStatic.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/PrettyStackTrace.h"
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#include "llvm/Support/Signals.h"
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#include "llvm/Support/SourceMgr.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Support/system_error.h"
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using namespace llvm;
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static cl::list<std::string>
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InputFilenames(cl::Positional, cl::desc("<input files>"),
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cl::ZeroOrMore);
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static cl::opt<bool>
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DumpTags("dump-tags", cl::desc("List all tags encountered in input"));
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static StringRef ToolName;
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/// Trivial lexer for the markup parser. Input is always handled a character
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/// at a time. The lexer just encapsulates EOF and lookahead handling.
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class MarkupLexer {
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StringRef::const_iterator Start;
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StringRef::const_iterator CurPtr;
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StringRef::const_iterator End;
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public:
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MarkupLexer(StringRef Source)
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: Start(Source.begin()), CurPtr(Source.begin()), End(Source.end()) {}
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// When processing non-markup, input is consumed a character at a time.
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bool isEOF() { return CurPtr == End; }
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int getNextChar() {
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if (CurPtr == End) return EOF;
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return *CurPtr++;
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}
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int peekNextChar() {
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if (CurPtr == End) return EOF;
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return *CurPtr;
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}
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StringRef::const_iterator getPosition() const { return CurPtr; }
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};
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/// A markup tag is a name and a (usually empty) list of modifiers.
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class MarkupTag {
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StringRef Name;
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StringRef Modifiers;
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SMLoc StartLoc;
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public:
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MarkupTag(StringRef n, StringRef m, SMLoc Loc)
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: Name(n), Modifiers(m), StartLoc(Loc) {}
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StringRef getName() const { return Name; }
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StringRef getModifiers() const { return Modifiers; }
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SMLoc getLoc() const { return StartLoc; }
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};
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/// A simple parser implementation for creating MarkupTags from input text.
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class MarkupParser {
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MarkupLexer &Lex;
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SourceMgr &SM;
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public:
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MarkupParser(MarkupLexer &lex, SourceMgr &SrcMgr) : Lex(lex), SM(SrcMgr) {}
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/// Create a MarkupTag from the current position in the MarkupLexer.
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/// The parseTag() method should be called when the lexer has processed
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/// the opening '<' character. Input will be consumed up to and including
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/// the ':' which terminates the tag open.
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MarkupTag parseTag();
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/// Issue a diagnostic and terminate program execution.
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void FatalError(SMLoc Loc, StringRef Msg);
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};
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void MarkupParser::FatalError(SMLoc Loc, StringRef Msg) {
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SM.PrintMessage(Loc, SourceMgr::DK_Error, Msg);
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exit(1);
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}
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// Example handler for when a tag is recognized.
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static void processStartTag(MarkupTag &Tag) {
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// If we're just printing the tags, do that, otherwise do some simple
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// colorization.
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if (DumpTags) {
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outs() << Tag.getName();
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if (Tag.getModifiers().size())
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outs() << " " << Tag.getModifiers();
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outs() << "\n";
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return;
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}
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if (!outs().has_colors())
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return;
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// Color registers as red and immediates as cyan. Those don't have nested
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// tags, so don't bother keeping a stack of colors to reset to.
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if (Tag.getName() == "reg")
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outs().changeColor(raw_ostream::RED);
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else if (Tag.getName() == "imm")
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outs().changeColor(raw_ostream::CYAN);
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}
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// Example handler for when the end of a tag is recognized.
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static void processEndTag(MarkupTag &Tag) {
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// If we're printing the tags, there's nothing more to do here. Otherwise,
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// set the color back the normal.
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if (DumpTags)
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return;
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if (!outs().has_colors())
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return;
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// Just reset to basic white.
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outs().changeColor(raw_ostream::WHITE, false);
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}
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MarkupTag MarkupParser::parseTag() {
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// First off, extract the tag into it's own StringRef so we can look at it
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// outside of the context of consuming input.
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StringRef::const_iterator Start = Lex.getPosition();
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SMLoc Loc = SMLoc::getFromPointer(Start - 1);
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while(Lex.getNextChar() != ':') {
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// EOF is an error.
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if (Lex.isEOF())
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FatalError(SMLoc::getFromPointer(Start), "unterminated markup tag");
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}
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StringRef RawTag(Start, Lex.getPosition() - Start - 1);
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std::pair<StringRef, StringRef> SplitTag = RawTag.split(' ');
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return MarkupTag(SplitTag.first, SplitTag.second, Loc);
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}
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static void parseMCMarkup(StringRef Filename) {
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OwningPtr<MemoryBuffer> BufferPtr;
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if (error_code ec = MemoryBuffer::getFileOrSTDIN(Filename, BufferPtr)) {
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errs() << ToolName << ": " << ec.message() << '\n';
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return;
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}
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MemoryBuffer *Buffer = BufferPtr.take();
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SourceMgr SrcMgr;
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// Tell SrcMgr about this buffer, which is what the parser will pick up.
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SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
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StringRef InputSource = Buffer->getBuffer();
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MarkupLexer Lex(InputSource);
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MarkupParser Parser(Lex, SrcMgr);
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SmallVector<MarkupTag, 4> TagStack;
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for (int CurChar = Lex.getNextChar();
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CurChar != EOF;
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CurChar = Lex.getNextChar()) {
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switch (CurChar) {
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case '<': {
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// A "<<" is output as a literal '<' and does not start a markup tag.
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if (Lex.peekNextChar() == '<') {
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(void)Lex.getNextChar();
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break;
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}
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// Parse the markup entry.
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TagStack.push_back(Parser.parseTag());
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// Do any special handling for the start of a tag.
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processStartTag(TagStack.back());
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continue;
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}
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case '>': {
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SMLoc Loc = SMLoc::getFromPointer(Lex.getPosition() - 1);
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// A ">>" is output as a literal '>' and does not end a markup tag.
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if (Lex.peekNextChar() == '>') {
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(void)Lex.getNextChar();
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break;
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}
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// Close out the innermost tag.
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if (TagStack.empty())
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Parser.FatalError(Loc, "'>' without matching '<'");
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// Do any special handling for the end of a tag.
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processEndTag(TagStack.back());
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TagStack.pop_back();
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continue;
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}
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default:
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break;
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}
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// For anything else, just echo the character back out.
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if (!DumpTags && CurChar != EOF)
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outs() << (char)CurChar;
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}
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// If there are any unterminated markup tags, issue diagnostics for them.
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while (!TagStack.empty()) {
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MarkupTag &Tag = TagStack.back();
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SrcMgr.PrintMessage(Tag.getLoc(), SourceMgr::DK_Error,
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"unterminated markup tag");
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TagStack.pop_back();
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}
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}
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int main(int argc, char **argv) {
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// Print a stack trace if we signal out.
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sys::PrintStackTraceOnErrorSignal();
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PrettyStackTraceProgram X(argc, argv);
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llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
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cl::ParseCommandLineOptions(argc, argv, "llvm MC markup parser\n");
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ToolName = argv[0];
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// If no input files specified, read from stdin.
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if (InputFilenames.size() == 0)
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InputFilenames.push_back("-");
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std::for_each(InputFilenames.begin(), InputFilenames.end(),
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parseMCMarkup);
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return 0;
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}
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