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 "CodeGenInstruction.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) { return isAlnum(C) || C == '_'; }
23 
24 std::string AsmWriterOperand::getCode(bool PassSubtarget) const {
25   if (OperandType == isLiteralTextOperand) {
26     if (Str.size() == 1)
27       return "O << '" + Str + "';";
28     return "O << \"" + Str + "\";";
29   }
30 
31   if (OperandType == isLiteralStatementOperand)
32     return Str;
33 
34   std::string Result = Str + "(MI";
35   if (PCRel)
36     Result += ", Address";
37   if (MIOpNo != ~0U)
38     Result += ", " + utostr(MIOpNo);
39   if (PassSubtarget)
40     Result += ", STI";
41   Result += ", O";
42   if (!MiModifier.empty())
43     Result += ", \"" + MiModifier + '"';
44   return Result + ");";
45 }
46 
47 /// ParseAsmString - Parse the specified Instruction's AsmString into this
48 /// AsmWriterInst.
49 ///
50 AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI, unsigned CGIIndex,
51                              unsigned Variant)
52     : CGI(&CGI), CGIIndex(CGIIndex) {
53 
54   // NOTE: Any extensions to this code need to be mirrored in the
55   // AsmPrinter::printInlineAsm code that executes as compile time (assuming
56   // that inline asm strings should also get the new feature)!
57   std::string AsmString = CGI.FlattenAsmStringVariants(CGI.AsmString, Variant);
58   std::string::size_type LastEmitted = 0;
59   while (LastEmitted != AsmString.size()) {
60     std::string::size_type DollarPos =
61       AsmString.find_first_of("$\\", LastEmitted);
62     if (DollarPos == std::string::npos) DollarPos = AsmString.size();
63 
64     // Emit a constant string fragment.
65     if (DollarPos != LastEmitted) {
66       for (; LastEmitted != DollarPos; ++LastEmitted)
67         switch (AsmString[LastEmitted]) {
68           case '\n':
69             AddLiteralString("\\n");
70             break;
71           case '\t':
72             AddLiteralString("\\t");
73             break;
74           case '"':
75             AddLiteralString("\\\"");
76             break;
77           case '\\':
78             AddLiteralString("\\\\");
79             break;
80           default:
81             AddLiteralString(std::string(1, AsmString[LastEmitted]));
82             break;
83         }
84     } else if (AsmString[DollarPos] == '\\') {
85       if (DollarPos+1 != AsmString.size()) {
86         if (AsmString[DollarPos+1] == 'n') {
87           AddLiteralString("\\n");
88         } else if (AsmString[DollarPos+1] == 't') {
89           AddLiteralString("\\t");
90         } else if (std::string("${|}\\").find(AsmString[DollarPos+1])
91                    != std::string::npos) {
92           AddLiteralString(std::string(1, AsmString[DollarPos+1]));
93         } else {
94           PrintFatalError(
95               CGI.TheDef->getLoc(),
96               "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       StringRef VarName(AsmString.data()+DollarPos+1, VarEnd-DollarPos-1);
123 
124       // Modifier - Support ${foo:modifier} syntax, where "modifier" is passed
125       // into printOperand.  Also support ${:feature}, which is passed into
126       // PrintSpecial.
127       std::string Modifier;
128 
129       // In order to avoid starting the next string at the terminating curly
130       // brace, advance the end position past it if we found an opening curly
131       // brace.
132       if (hasCurlyBraces) {
133         if (VarEnd >= AsmString.size())
134           PrintFatalError(
135               CGI.TheDef->getLoc(),
136               "Reached end of string before terminating curly brace in '" +
137                   CGI.TheDef->getName() + "'");
138 
139         // Look for a modifier string.
140         if (AsmString[VarEnd] == ':') {
141           ++VarEnd;
142           if (VarEnd >= AsmString.size())
143             PrintFatalError(
144                 CGI.TheDef->getLoc(),
145                 "Reached end of string before terminating curly brace in '" +
146                     CGI.TheDef->getName() + "'");
147 
148           std::string::size_type ModifierStart = VarEnd;
149           while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
150             ++VarEnd;
151           Modifier = AsmString.substr(ModifierStart, VarEnd - ModifierStart);
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