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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(bool PassSubtarget) 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   if (PassSubtarget)
     43     Result += ", STI";
     44   Result += ", O";
     45   if (!MiModifier.empty())
     46     Result += ", \"" + MiModifier + '"';
     47   return Result + ");";
     48 }
     49 
     50 /// ParseAsmString - Parse the specified Instruction's AsmString into this
     51 /// AsmWriterInst.
     52 ///
     53 AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI, unsigned CGIIndex,
     54                              unsigned Variant)
     55     : CGI(&CGI), CGIIndex(CGIIndex) {
     56 
     57   // NOTE: Any extensions to this code need to be mirrored in the
     58   // AsmPrinter::printInlineAsm code that executes as compile time (assuming
     59   // that inline asm strings should also get the new feature)!
     60   std::string AsmString = CGI.FlattenAsmStringVariants(CGI.AsmString, Variant);
     61   std::string::size_type LastEmitted = 0;
     62   while (LastEmitted != AsmString.size()) {
     63     std::string::size_type DollarPos =
     64       AsmString.find_first_of("$\\", LastEmitted);
     65     if (DollarPos == std::string::npos) DollarPos = AsmString.size();
     66 
     67     // Emit a constant string fragment.
     68     if (DollarPos != LastEmitted) {
     69       for (; LastEmitted != DollarPos; ++LastEmitted)
     70         switch (AsmString[LastEmitted]) {
     71           case '\n':
     72             AddLiteralString("\\n");
     73             break;
     74           case '\t':
     75             AddLiteralString("\\t");
     76             break;
     77           case '"':
     78             AddLiteralString("\\\"");
     79             break;
     80           case '\\':
     81             AddLiteralString("\\\\");
     82             break;
     83           default:
     84             AddLiteralString(std::string(1, AsmString[LastEmitted]));
     85             break;
     86         }
     87     } else if (AsmString[DollarPos] == '\\') {
     88       if (DollarPos+1 != AsmString.size()) {
     89         if (AsmString[DollarPos+1] == 'n') {
     90           AddLiteralString("\\n");
     91         } else if (AsmString[DollarPos+1] == 't') {
     92           AddLiteralString("\\t");
     93         } else if (std::string("${|}\\").find(AsmString[DollarPos+1])
     94                    != std::string::npos) {
     95           AddLiteralString(std::string(1, AsmString[DollarPos+1]));
     96         } else {
     97           PrintFatalError("Non-supported escaped character found in instruction '" +
     98             CGI.TheDef->getName() + "'!");
     99         }
    100         LastEmitted = DollarPos+2;
    101         continue;
    102       }
    103     } else if (DollarPos+1 != AsmString.size() &&
    104                AsmString[DollarPos+1] == '$') {
    105       AddLiteralString("$");  // "$$" -> $
    106       LastEmitted = DollarPos+2;
    107     } else {
    108       // Get the name of the variable.
    109       std::string::size_type VarEnd = DollarPos+1;
    110 
    111       // handle ${foo}bar as $foo by detecting whether the character following
    112       // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
    113       // so the variable name does not contain the leading curly brace.
    114       bool hasCurlyBraces = false;
    115       if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
    116         hasCurlyBraces = true;
    117         ++DollarPos;
    118         ++VarEnd;
    119       }
    120 
    121       while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
    122         ++VarEnd;
    123       StringRef VarName(AsmString.data()+DollarPos+1, VarEnd-DollarPos-1);
    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           std::string::size_type 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.emplace_back("PrintSpecial", ~0U, Modifier);
    166       } else {
    167         // Otherwise, normal operand.
    168         unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
    169         CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
    170 
    171         unsigned MIOp = OpInfo.MIOperandNo;
    172         Operands.emplace_back(OpInfo.PrinterMethodName, MIOp, Modifier);
    173       }
    174       LastEmitted = VarEnd;
    175     }
    176   }
    177 
    178   Operands.emplace_back("return;", AsmWriterOperand::isLiteralStatementOperand);
    179 }
    180 
    181 /// MatchesAllButOneOp - If this instruction is exactly identical to the
    182 /// specified instruction except for one differing operand, return the differing
    183 /// operand number.  If more than one operand mismatches, return ~1, otherwise
    184 /// if the instructions are identical return ~0.
    185 unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
    186   if (Operands.size() != Other.Operands.size()) return ~1;
    187 
    188   unsigned MismatchOperand = ~0U;
    189   for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
    190     if (Operands[i] != Other.Operands[i]) {
    191       if (MismatchOperand != ~0U)  // Already have one mismatch?
    192         return ~1U;
    193       MismatchOperand = i;
    194     }
    195   }
    196   return MismatchOperand;
    197 }
    198