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