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      1 //===- lib/MC/MCSymbol.cpp - MCSymbol implementation ----------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "llvm/MC/MCSymbol.h"
     11 #include "llvm/MC/MCExpr.h"
     12 #include "llvm/Support/Debug.h"
     13 #include "llvm/Support/raw_ostream.h"
     14 using namespace llvm;
     15 
     16 // Sentinel value for the absolute pseudo section.
     17 const MCSection *MCSymbol::AbsolutePseudoSection =
     18   reinterpret_cast<const MCSection *>(1);
     19 
     20 static bool isAcceptableChar(char C) {
     21   if ((C < 'a' || C > 'z') &&
     22       (C < 'A' || C > 'Z') &&
     23       (C < '0' || C > '9') &&
     24       C != '_' && C != '$' && C != '.' && C != '@')
     25     return false;
     26   return true;
     27 }
     28 
     29 /// NameNeedsQuoting - Return true if the identifier \p Str needs quotes to be
     30 /// syntactically correct.
     31 static bool NameNeedsQuoting(StringRef Str) {
     32   assert(!Str.empty() && "Cannot create an empty MCSymbol");
     33 
     34   // If any of the characters in the string is an unacceptable character, force
     35   // quotes.
     36   for (unsigned i = 0, e = Str.size(); i != e; ++i)
     37     if (!isAcceptableChar(Str[i]))
     38       return true;
     39   return false;
     40 }
     41 
     42 const MCSymbol &MCSymbol::AliasedSymbol() const {
     43   const MCSymbol *S = this;
     44   while (S->isVariable()) {
     45     const MCExpr *Value = S->getVariableValue();
     46     if (Value->getKind() != MCExpr::SymbolRef)
     47       return *S;
     48     const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
     49     S = &Ref->getSymbol();
     50   }
     51   return *S;
     52 }
     53 
     54 void MCSymbol::setVariableValue(const MCExpr *Value) {
     55   assert(!IsUsed && "Cannot set a variable that has already been used.");
     56   assert(Value && "Invalid variable value!");
     57   this->Value = Value;
     58   this->Section = nullptr;
     59 }
     60 
     61 void MCSymbol::print(raw_ostream &OS) const {
     62   // The name for this MCSymbol is required to be a valid target name.  However,
     63   // some targets support quoting names with funny characters.  If the name
     64   // contains a funny character, then print it quoted.
     65   StringRef Name = getName();
     66   if (!NameNeedsQuoting(Name)) {
     67     OS << Name;
     68     return;
     69   }
     70 
     71   OS << '"';
     72   for (unsigned I = 0, E = Name.size(); I != E; ++I) {
     73     char C = Name[I];
     74     if (C == '\n')
     75       OS << "\\n";
     76     else if (C == '"')
     77       OS << "\\\"";
     78     else
     79       OS << C;
     80   }
     81   OS << '"';
     82 }
     83 
     84 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
     85 void MCSymbol::dump() const {
     86   print(dbgs());
     87 }
     88 #endif
     89