1//===- AsmWriterInst.h - Classes encapsulating a printable inst -----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// These classes implement a parser for assembly strings.
10//
11//===----------------------------------------------------------------------===//
12
13#include "AsmWriterInst.h"
14#include "CodeGenTarget.h"
15#include "llvm/ADT/StringExtras.h"
16#include "llvm/TableGen/Error.h"
17#include "llvm/TableGen/Record.h"
18
19using namespace llvm;
20
21static bool isIdentChar(char C) {
22  return (C >= 'a' && C <= 'z') ||
23  (C >= 'A' && C <= 'Z') ||
24  (C >= '0' && C <= '9') ||
25  C == '_';
26}
27
28std::string AsmWriterOperand::getCode(bool PassSubtarget) const {
29  if (OperandType == isLiteralTextOperand) {
30    if (Str.size() == 1)
31      return "O << '" + Str + "';";
32    return "O << \"" + Str + "\";";
33  }
34
35  if (OperandType == isLiteralStatementOperand)
36    return Str;
37
38  std::string Result = Str + "(MI";
39  if (PCRel)
40    Result += ", Address";
41  if (MIOpNo != ~0U)
42    Result += ", " + utostr(MIOpNo);
43  if (PassSubtarget)
44    Result += ", STI";
45  Result += ", O";
46  if (!MiModifier.empty())
47    Result += ", \"" + MiModifier + '"';
48  return Result + ");";
49}
50
51/// ParseAsmString - Parse the specified Instruction's AsmString into this
52/// AsmWriterInst.
53///
54AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI, unsigned CGIIndex,
55                             unsigned Variant)
56    : CGI(&CGI), CGIIndex(CGIIndex) {
57
58  // NOTE: Any extensions to this code need to be mirrored in the
59  // AsmPrinter::printInlineAsm code that executes as compile time (assuming
60  // that inline asm strings should also get the new feature)!
61  std::string AsmString = CGI.FlattenAsmStringVariants(CGI.AsmString, Variant);
62  std::string::size_type LastEmitted = 0;
63  while (LastEmitted != AsmString.size()) {
64    std::string::size_type DollarPos =
65      AsmString.find_first_of("$\\", LastEmitted);
66    if (DollarPos == std::string::npos) DollarPos = AsmString.size();
67
68    // Emit a constant string fragment.
69    if (DollarPos != LastEmitted) {
70      for (; LastEmitted != DollarPos; ++LastEmitted)
71        switch (AsmString[LastEmitted]) {
72          case '\n':
73            AddLiteralString("\\n");
74            break;
75          case '\t':
76            AddLiteralString("\\t");
77            break;
78          case '"':
79            AddLiteralString("\\\"");
80            break;
81          case '\\':
82            AddLiteralString("\\\\");
83            break;
84          default:
85            AddLiteralString(std::string(1, AsmString[LastEmitted]));
86            break;
87        }
88    } else if (AsmString[DollarPos] == '\\') {
89      if (DollarPos+1 != AsmString.size()) {
90        if (AsmString[DollarPos+1] == 'n') {
91          AddLiteralString("\\n");
92        } else if (AsmString[DollarPos+1] == 't') {
93          AddLiteralString("\\t");
94        } else if (std::string("${|}\\").find(AsmString[DollarPos+1])
95                   != std::string::npos) {
96          AddLiteralString(std::string(1, AsmString[DollarPos+1]));
97        } else {
98          PrintFatalError(
99              CGI.TheDef->getLoc(),
100              "Non-supported escaped character found in instruction '" +
101                  CGI.TheDef->getName() + "'!");
102        }
103        LastEmitted = DollarPos+2;
104        continue;
105      }
106    } else if (DollarPos+1 != AsmString.size() &&
107               AsmString[DollarPos+1] == '$') {
108      AddLiteralString("$");  // "$$" -> $
109      LastEmitted = DollarPos+2;
110    } else {
111      // Get the name of the variable.
112      std::string::size_type VarEnd = DollarPos+1;
113
114      // handle ${foo}bar as $foo by detecting whether the character following
115      // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
116      // so the variable name does not contain the leading curly brace.
117      bool hasCurlyBraces = false;
118      if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
119        hasCurlyBraces = true;
120        ++DollarPos;
121        ++VarEnd;
122      }
123
124      while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
125        ++VarEnd;
126      StringRef VarName(AsmString.data()+DollarPos+1, VarEnd-DollarPos-1);
127
128      // Modifier - Support ${foo:modifier} syntax, where "modifier" is passed
129      // into printOperand.  Also support ${:feature}, which is passed into
130      // PrintSpecial.
131      std::string Modifier;
132
133      // In order to avoid starting the next string at the terminating curly
134      // brace, advance the end position past it if we found an opening curly
135      // brace.
136      if (hasCurlyBraces) {
137        if (VarEnd >= AsmString.size())
138          PrintFatalError(
139              CGI.TheDef->getLoc(),
140              "Reached end of string before terminating curly brace in '" +
141                  CGI.TheDef->getName() + "'");
142
143        // Look for a modifier string.
144        if (AsmString[VarEnd] == ':') {
145          ++VarEnd;
146          if (VarEnd >= AsmString.size())
147            PrintFatalError(
148                CGI.TheDef->getLoc(),
149                "Reached end of string before terminating curly brace in '" +
150                    CGI.TheDef->getName() + "'");
151
152          std::string::size_type ModifierStart = VarEnd;
153          while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
154            ++VarEnd;
155          Modifier = std::string(AsmString.begin()+ModifierStart,
156                                 AsmString.begin()+VarEnd);
157          if (Modifier.empty())
158            PrintFatalError(CGI.TheDef->getLoc(),
159                            "Bad operand modifier name in '" +
160                                CGI.TheDef->getName() + "'");
161        }
162
163        if (AsmString[VarEnd] != '}')
164          PrintFatalError(
165              CGI.TheDef->getLoc(),
166              "Variable name beginning with '{' did not end with '}' in '" +
167                  CGI.TheDef->getName() + "'");
168        ++VarEnd;
169      }
170      if (VarName.empty() && Modifier.empty())
171        PrintFatalError(CGI.TheDef->getLoc(),
172                        "Stray '$' in '" + CGI.TheDef->getName() +
173                            "' asm string, maybe you want $$?");
174
175      if (VarName.empty()) {
176        // Just a modifier, pass this into PrintSpecial.
177        Operands.emplace_back("PrintSpecial", ~0U, Modifier);
178      } else {
179        // Otherwise, normal operand.
180        unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
181        CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
182
183        unsigned MIOp = OpInfo.MIOperandNo;
184        Operands.emplace_back(OpInfo.PrinterMethodName, MIOp, Modifier,
185                              AsmWriterOperand::isMachineInstrOperand,
186                              OpInfo.OperandType == "MCOI::OPERAND_PCREL");
187      }
188      LastEmitted = VarEnd;
189    }
190  }
191
192  Operands.emplace_back("return;", AsmWriterOperand::isLiteralStatementOperand);
193}
194
195/// MatchesAllButOneOp - If this instruction is exactly identical to the
196/// specified instruction except for one differing operand, return the differing
197/// operand number.  If more than one operand mismatches, return ~1, otherwise
198/// if the instructions are identical return ~0.
199unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
200  if (Operands.size() != Other.Operands.size()) return ~1;
201
202  unsigned MismatchOperand = ~0U;
203  for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
204    if (Operands[i] != Other.Operands[i]) {
205      if (MismatchOperand != ~0U)  // Already have one mismatch?
206        return ~1U;
207      MismatchOperand = i;
208    }
209  }
210  return MismatchOperand;
211}
212