[asm] Convert AsmPrinter::PrintSpecial() to StringRef

[thakis]

Summary

No behavior change.

[hans]

Nice!

llvm/include/llvm/CodeGen/AsmPrinter.h

public:
 
   /// Print information related to the specified machine instr that is
   /// independent of the operand, and may be independent of the instr itself.
   /// This can be useful for portably encoding the comment character or other
   /// bits of target-specific knowledge into the asmstrings.  The syntax used is
   /// ${:comment}.  Targets can override this to add support for their own
   /// strange codes.
   virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
-                            const char *Code) const;
+                            StringRef Code) const;
 
   /// Print the MachineOperand as a symbol. Targets with complex handling of
   /// symbol references should override the base implementation.
   virtual void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS);
 
   /// Print the specified operand of MI, an INLINEASM instruction, using the
   /// specified assembler variant.  Targets should override this to format as
   /// appropriate.  This method can return true if the operand is erroneous.

llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

case '$': {
       if (HasCurlyBraces && LastEmitted[0] == ':') {
         ++LastEmitted;
         const char *StrStart = LastEmitted;
         const char *StrEnd = strchr(StrStart, '}');
         if (!StrEnd)
           report_fatal_error("Unterminated ${:foo} operand in inline asm"
                              " string: '" + Twine(AsmStr) + "'");
 
-        std::string Val(StrStart, StrEnd);
-        AP->PrintSpecial(MI, OS, Val.c_str());
+        AP->PrintSpecial(MI, OS, StringRef(StrStart, StrEnd - StrStart));
         LastEmitted = StrEnd+1;
         break;
       }
 
       const char *IDStart = LastEmitted;
       const char *IDEnd = IDStart;
       while (isDigit(*IDEnd))
         ++IDEnd;
case '$': {
       // PrintSpecial.
       if (HasCurlyBraces && *LastEmitted == ':') {
         ++LastEmitted;
         const char *StrStart = LastEmitted;
         const char *StrEnd = strchr(StrStart, '}');
         if (!StrEnd)
           report_fatal_error("Unterminated ${:foo} operand in inline asm"
                              " string: '" + Twine(AsmStr) + "'");
-        if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
-          std::string Val(StrStart, StrEnd);
-          AP->PrintSpecial(MI, OS, Val.c_str());
-        }
+        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
+          AP->PrintSpecial(MI, OS, StringRef(StrStart, StrEnd - StrStart));
         LastEmitted = StrEnd+1;
         break;
       }
 
       const char *IDStart = LastEmitted;
       const char *IDEnd = IDStart;
       while (isDigit(*IDEnd))
         ++IDEnd;

 
 /// PrintSpecial - Print information related to the specified machine instr
 /// that is independent of the operand, and may be independent of the instr
 /// itself.  This can be useful for portably encoding the comment character
 /// or other bits of target-specific knowledge into the asmstrings.  The
 /// syntax used is ${:comment}.  Targets can override this to add support
 /// for their own strange codes.
 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
-                              const char *Code) const {
-  if (!strcmp(Code, "private")) {
+                              StringRef Code) const {
+  if (Code == "private") {
     const DataLayout &DL = MF->getDataLayout();
     OS << DL.getPrivateGlobalPrefix();
-  } else if (!strcmp(Code, "comment")) {
+  } else if (Code == "comment") {
     OS << MAI->getCommentString();
-  } else if (!strcmp(Code, "uid")) {
+  } else if (Code == "uid") {
     // Comparing the address of MI isn't sufficient, because machineinstrs may
     // be allocated to the same address across functions.
 
     // If this is a new LastFn instruction, bump the counter.
     if (LastMI != MI || LastFn != getFunctionNumber()) {
       ++Counter;
       LastMI = MI;
       LastFn = getFunctionNumber();