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) {
22   return (C >= 'a' && C <= 'z') ||
23   (C >= 'A' && C <= 'Z') ||
24   (C >= '0' && C <= '9') ||
25   C == '_';
26 }
27 
28 std::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 ///
52 AsmWriterInst::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("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("Reached end of string before terminating curly brace in '"
135             + CGI.TheDef->getName() + "'");
136 
137         // Look for a modifier string.
138         if (AsmString[VarEnd] == ':') {
139           ++VarEnd;
140           if (VarEnd >= AsmString.size())
141             PrintFatalError("Reached end of string before terminating curly brace in '"
142               + CGI.TheDef->getName() + "'");
143 
144           std::string::size_type ModifierStart = VarEnd;
145           while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
146             ++VarEnd;
147           Modifier = std::string(AsmString.begin()+ModifierStart,
148                                  AsmString.begin()+VarEnd);
149           if (Modifier.empty())
150             PrintFatalError("Bad operand modifier name in '"+ CGI.TheDef->getName() + "'");
151         }
152 
153         if (AsmString[VarEnd] != '}')
154           PrintFatalError("Variable name beginning with '{' did not end with '}' in '"
155             + CGI.TheDef->getName() + "'");
156         ++VarEnd;
157       }
158       if (VarName.empty() && Modifier.empty())
159         PrintFatalError("Stray '$' in '" + CGI.TheDef->getName() +
160           "' asm string, maybe you want $$?");
161 
162       if (VarName.empty()) {
163         // Just a modifier, pass this into PrintSpecial.
164         Operands.emplace_back("PrintSpecial", ~0U, Modifier);
165       } else {
166         // Otherwise, normal operand.
167         unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
168         CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
169 
170         unsigned MIOp = OpInfo.MIOperandNo;
171         Operands.emplace_back(OpInfo.PrinterMethodName, MIOp, Modifier);
172       }
173       LastEmitted = VarEnd;
174     }
175   }
176 
177   Operands.emplace_back("return;", AsmWriterOperand::isLiteralStatementOperand);
178 }
179 
180 /// MatchesAllButOneOp - If this instruction is exactly identical to the
181 /// specified instruction except for one differing operand, return the differing
182 /// operand number.  If more than one operand mismatches, return ~1, otherwise
183 /// if the instructions are identical return ~0.
184 unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
185   if (Operands.size() != Other.Operands.size()) return ~1;
186 
187   unsigned MismatchOperand = ~0U;
188   for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
189     if (Operands[i] != Other.Operands[i]) {
190       if (MismatchOperand != ~0U)  // Already have one mismatch?
191         return ~1U;
192       MismatchOperand = i;
193     }
194   }
195   return MismatchOperand;
196 }
197