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      1 //===- AsmWriterInst.h - Classes encapsulating a printable inst -----------===//
      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 // These classes implement a parser for assembly strings.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "AsmWriterInst.h"
     15 #include "CodeGenTarget.h"
     16 #include "llvm/ADT/StringExtras.h"
     17 #include "llvm/TableGen/Error.h"
     18 #include "llvm/TableGen/Record.h"
     19 
     20 using namespace llvm;
     21 
     22 static bool isIdentChar(char C) {
     23   return (C >= 'a' && C <= 'z') ||
     24   (C >= 'A' && C <= 'Z') ||
     25   (C >= '0' && C <= '9') ||
     26   C == '_';
     27 }
     28 
     29 std::string AsmWriterOperand::getCode() const {
     30   if (OperandType == isLiteralTextOperand) {
     31     if (Str.size() == 1)
     32       return "O << '" + Str + "'; ";
     33     return "O << \"" + Str + "\"; ";
     34   }
     35 
     36   if (OperandType == isLiteralStatementOperand)
     37     return Str;
     38 
     39   std::string Result = Str + "(MI";
     40   if (MIOpNo != ~0U)
     41     Result += ", " + utostr(MIOpNo);
     42   Result += ", O";
     43   if (!MiModifier.empty())
     44     Result += ", \"" + MiModifier + '"';
     45   return Result + "); ";
     46 }
     47 
     48 /// ParseAsmString - Parse the specified Instruction's AsmString into this
     49 /// AsmWriterInst.
     50 ///
     51 AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI,
     52                              unsigned Variant,
     53                              int OperandSpacing) {
     54   this->CGI = &CGI;
     55 
     56   // NOTE: Any extensions to this code need to be mirrored in the
     57   // AsmPrinter::printInlineAsm code that executes as compile time (assuming
     58   // that inline asm strings should also get the new feature)!
     59   std::string AsmString = CGI.FlattenAsmStringVariants(CGI.AsmString, Variant);
     60   std::string::size_type LastEmitted = 0;
     61   while (LastEmitted != AsmString.size()) {
     62     std::string::size_type DollarPos =
     63       AsmString.find_first_of("$\\", LastEmitted);
     64     if (DollarPos == std::string::npos) DollarPos = AsmString.size();
     65 
     66     // Emit a constant string fragment.
     67     if (DollarPos != LastEmitted) {
     68       for (; LastEmitted != DollarPos; ++LastEmitted)
     69         switch (AsmString[LastEmitted]) {
     70           case '\n':
     71             AddLiteralString("\\n");
     72             break;
     73           case '\t':
     74             AddLiteralString("\\t");
     75             break;
     76           case '"':
     77             AddLiteralString("\\\"");
     78             break;
     79           case '\\':
     80             AddLiteralString("\\\\");
     81             break;
     82           default:
     83             AddLiteralString(std::string(1, AsmString[LastEmitted]));
     84             break;
     85         }
     86     } else if (AsmString[DollarPos] == '\\') {
     87       if (DollarPos+1 != AsmString.size()) {
     88         if (AsmString[DollarPos+1] == 'n') {
     89           AddLiteralString("\\n");
     90         } else if (AsmString[DollarPos+1] == 't') {
     91           AddLiteralString("\\t");
     92         } else if (std::string("${|}\\").find(AsmString[DollarPos+1])
     93                    != std::string::npos) {
     94           AddLiteralString(std::string(1, AsmString[DollarPos+1]));
     95         } else {
     96           PrintFatalError("Non-supported escaped character found in instruction '" +
     97             CGI.TheDef->getName() + "'!");
     98         }
     99         LastEmitted = DollarPos+2;
    100         continue;
    101       }
    102     } else if (DollarPos+1 != AsmString.size() &&
    103                AsmString[DollarPos+1] == '$') {
    104       AddLiteralString("$");  // "$$" -> $
    105       LastEmitted = DollarPos+2;
    106     } else {
    107       // Get the name of the variable.
    108       std::string::size_type VarEnd = DollarPos+1;
    109 
    110       // handle ${foo}bar as $foo by detecting whether the character following
    111       // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
    112       // so the variable name does not contain the leading curly brace.
    113       bool hasCurlyBraces = false;
    114       if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
    115         hasCurlyBraces = true;
    116         ++DollarPos;
    117         ++VarEnd;
    118       }
    119 
    120       while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
    121         ++VarEnd;
    122       std::string VarName(AsmString.begin()+DollarPos+1,
    123                           AsmString.begin()+VarEnd);
    124 
    125       // Modifier - Support ${foo:modifier} syntax, where "modifier" is passed
    126       // into printOperand.  Also support ${:feature}, which is passed into
    127       // PrintSpecial.
    128       std::string Modifier;
    129 
    130       // In order to avoid starting the next string at the terminating curly
    131       // brace, advance the end position past it if we found an opening curly
    132       // brace.
    133       if (hasCurlyBraces) {
    134         if (VarEnd >= AsmString.size())
    135           PrintFatalError("Reached end of string before terminating curly brace in '"
    136             + CGI.TheDef->getName() + "'");
    137 
    138         // Look for a modifier string.
    139         if (AsmString[VarEnd] == ':') {
    140           ++VarEnd;
    141           if (VarEnd >= AsmString.size())
    142             PrintFatalError("Reached end of string before terminating curly brace in '"
    143               + CGI.TheDef->getName() + "'");
    144 
    145           unsigned ModifierStart = VarEnd;
    146           while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
    147             ++VarEnd;
    148           Modifier = std::string(AsmString.begin()+ModifierStart,
    149                                  AsmString.begin()+VarEnd);
    150           if (Modifier.empty())
    151             PrintFatalError("Bad operand modifier name in '"+ CGI.TheDef->getName() + "'");
    152         }
    153 
    154         if (AsmString[VarEnd] != '}')
    155           PrintFatalError("Variable name beginning with '{' did not end with '}' in '"
    156             + CGI.TheDef->getName() + "'");
    157         ++VarEnd;
    158       }
    159       if (VarName.empty() && Modifier.empty())
    160         PrintFatalError("Stray '$' in '" + CGI.TheDef->getName() +
    161           "' asm string, maybe you want $$?");
    162 
    163       if (VarName.empty()) {
    164         // Just a modifier, pass this into PrintSpecial.
    165         Operands.push_back(AsmWriterOperand("PrintSpecial",
    166                                             ~0U,
    167                                             ~0U,
    168                                             Modifier));
    169       } else {
    170         // Otherwise, normal operand.
    171         unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
    172         CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
    173 
    174         unsigned MIOp = OpInfo.MIOperandNo;
    175         Operands.push_back(AsmWriterOperand(OpInfo.PrinterMethodName,
    176                                             OpNo, MIOp, Modifier));
    177       }
    178       LastEmitted = VarEnd;
    179     }
    180   }
    181 
    182   Operands.push_back(AsmWriterOperand("return;",
    183     AsmWriterOperand::isLiteralStatementOperand));
    184 }
    185 
    186 /// MatchesAllButOneOp - If this instruction is exactly identical to the
    187 /// specified instruction except for one differing operand, return the differing
    188 /// operand number.  If more than one operand mismatches, return ~1, otherwise
    189 /// if the instructions are identical return ~0.
    190 unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
    191   if (Operands.size() != Other.Operands.size()) return ~1;
    192 
    193   unsigned MismatchOperand = ~0U;
    194   for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
    195     if (Operands[i] != Other.Operands[i]) {
    196       if (MismatchOperand != ~0U)  // Already have one mismatch?
    197         return ~1U;
    198       MismatchOperand = i;
    199     }
    200   }
    201   return MismatchOperand;
    202 }
    203