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 (MIOpNo != ~0U)
40    Result += ", " + utostr(MIOpNo);
41  if (PassSubtarget)
42    Result += ", STI";
43  Result += ", O";
44  if (!MiModifier.empty())
45    Result += ", \"" + MiModifier + '"';
46  return Result + ");";
47}
48
49/// ParseAsmString - Parse the specified Instruction's AsmString into this
50/// AsmWriterInst.
51///
52AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI, unsigned CGIIndex,
53                             unsigned Variant)
54    : CGI(&CGI), CGIIndex(CGIIndex) {
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(
97              CGI.TheDef->getLoc(),
98              "Non-supported escaped character found in instruction '" +
99                  CGI.TheDef->getName() + "'!");
100        }
101        LastEmitted = DollarPos+2;
102        continue;
103      }
104    } else if (DollarPos+1 != AsmString.size() &&
105               AsmString[DollarPos+1] == '$') {
106      AddLiteralString("$");  // "$$" -> $
107      LastEmitted = DollarPos+2;
108    } else {
109      // Get the name of the variable.
110      std::string::size_type VarEnd = DollarPos+1;
111
112      // handle ${foo}bar as $foo by detecting whether the character following
113      // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
114      // so the variable name does not contain the leading curly brace.
115      bool hasCurlyBraces = false;
116      if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
117        hasCurlyBraces = true;
118        ++DollarPos;
119        ++VarEnd;
120      }
121
122      while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
123        ++VarEnd;
124      StringRef VarName(AsmString.data()+DollarPos+1, VarEnd-DollarPos-1);
125
126      // Modifier - Support ${foo:modifier} syntax, where "modifier" is passed
127      // into printOperand.  Also support ${:feature}, which is passed into
128      // PrintSpecial.
129      std::string Modifier;
130
131      // In order to avoid starting the next string at the terminating curly
132      // brace, advance the end position past it if we found an opening curly
133      // brace.
134      if (hasCurlyBraces) {
135        if (VarEnd >= AsmString.size())
136          PrintFatalError(
137              CGI.TheDef->getLoc(),
138              "Reached end of string before terminating curly brace in '" +
139                  CGI.TheDef->getName() + "'");
140
141        // Look for a modifier string.
142        if (AsmString[VarEnd] == ':') {
143          ++VarEnd;
144          if (VarEnd >= AsmString.size())
145            PrintFatalError(
146                CGI.TheDef->getLoc(),
147                "Reached end of string before terminating curly brace in '" +
148                    CGI.TheDef->getName() + "'");
149
150          std::string::size_type ModifierStart = VarEnd;
151          while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
152            ++VarEnd;
153          Modifier = std::string(AsmString.begin()+ModifierStart,
154                                 AsmString.begin()+VarEnd);
155          if (Modifier.empty())
156            PrintFatalError(CGI.TheDef->getLoc(),
157                            "Bad operand modifier name in '" +
158                                CGI.TheDef->getName() + "'");
159        }
160
161        if (AsmString[VarEnd] != '}')
162          PrintFatalError(
163              CGI.TheDef->getLoc(),
164              "Variable name beginning with '{' did not end with '}' in '" +
165                  CGI.TheDef->getName() + "'");
166        ++VarEnd;
167      }
168      if (VarName.empty() && Modifier.empty())
169        PrintFatalError(CGI.TheDef->getLoc(),
170                        "Stray '$' in '" + CGI.TheDef->getName() +
171                            "' asm string, maybe you want $$?");
172
173      if (VarName.empty()) {
174        // Just a modifier, pass this into PrintSpecial.
175        Operands.emplace_back("PrintSpecial", ~0U, Modifier);
176      } else {
177        // Otherwise, normal operand.
178        unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
179        CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
180
181        unsigned MIOp = OpInfo.MIOperandNo;
182        Operands.emplace_back(OpInfo.PrinterMethodName, MIOp, Modifier);
183      }
184      LastEmitted = VarEnd;
185    }
186  }
187
188  Operands.emplace_back("return;", AsmWriterOperand::isLiteralStatementOperand);
189}
190
191/// MatchesAllButOneOp - If this instruction is exactly identical to the
192/// specified instruction except for one differing operand, return the differing
193/// operand number.  If more than one operand mismatches, return ~1, otherwise
194/// if the instructions are identical return ~0.
195unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
196  if (Operands.size() != Other.Operands.size()) return ~1;
197
198  unsigned MismatchOperand = ~0U;
199  for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
200    if (Operands[i] != Other.Operands[i]) {
201      if (MismatchOperand != ~0U)  // Already have one mismatch?
202        return ~1U;
203      MismatchOperand = i;
204    }
205  }
206  return MismatchOperand;
207}
208