1 //===- AsmWriterInst.h - Classes encapsulating a printable inst -----------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // These classes implement a parser for assembly strings.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "AsmWriterInst.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) {
23   return (C >= 'a' && C <= 'z') ||
24   (C >= 'A' && C <= 'Z') ||
25   (C >= '0' && C <= '9') ||
26   C == '_';
27 }
28 
29 std::string AsmWriterOperand::getCode() const {
30   if (OperandType == isLiteralTextOperand) {
31     if (Str.size() == 1)
32       return "O << '" + Str + "'; ";
33     return "O << \"" + Str + "\"; ";
34   }
35 
36   if (OperandType == isLiteralStatementOperand)
37     return Str;
38 
39   std::string Result = Str + "(MI";
40   if (MIOpNo != ~0U)
41     Result += ", " + utostr(MIOpNo);
42   Result += ", O";
43   if (!MiModifier.empty())
44     Result += ", \"" + MiModifier + '"';
45   return Result + "); ";
46 }
47 
48 /// ParseAsmString - Parse the specified Instruction's AsmString into this
49 /// AsmWriterInst.
50 ///
51 AsmWriterInst::AsmWriterInst(const CodeGenInstruction &CGI, unsigned Variant) {
52   this->CGI = &CGI;
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("Non-supported escaped character found in instruction '" +
95             CGI.TheDef->getName() + "'!");
96         }
97         LastEmitted = DollarPos+2;
98         continue;
99       }
100     } else if (DollarPos+1 != AsmString.size() &&
101                AsmString[DollarPos+1] == '$') {
102       AddLiteralString("$");  // "$$" -> $
103       LastEmitted = DollarPos+2;
104     } else {
105       // Get the name of the variable.
106       std::string::size_type VarEnd = DollarPos+1;
107 
108       // handle ${foo}bar as $foo by detecting whether the character following
109       // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
110       // so the variable name does not contain the leading curly brace.
111       bool hasCurlyBraces = false;
112       if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
113         hasCurlyBraces = true;
114         ++DollarPos;
115         ++VarEnd;
116       }
117 
118       while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
119         ++VarEnd;
120       std::string VarName(AsmString.begin()+DollarPos+1,
121                           AsmString.begin()+VarEnd);
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("Reached end of string before terminating curly brace in '"
134             + CGI.TheDef->getName() + "'");
135 
136         // Look for a modifier string.
137         if (AsmString[VarEnd] == ':') {
138           ++VarEnd;
139           if (VarEnd >= AsmString.size())
140             PrintFatalError("Reached end of string before terminating curly brace in '"
141               + CGI.TheDef->getName() + "'");
142 
143           unsigned ModifierStart = VarEnd;
144           while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
145             ++VarEnd;
146           Modifier = std::string(AsmString.begin()+ModifierStart,
147                                  AsmString.begin()+VarEnd);
148           if (Modifier.empty())
149             PrintFatalError("Bad operand modifier name in '"+ CGI.TheDef->getName() + "'");
150         }
151 
152         if (AsmString[VarEnd] != '}')
153           PrintFatalError("Variable name beginning with '{' did not end with '}' in '"
154             + CGI.TheDef->getName() + "'");
155         ++VarEnd;
156       }
157       if (VarName.empty() && Modifier.empty())
158         PrintFatalError("Stray '$' in '" + CGI.TheDef->getName() +
159           "' asm string, maybe you want $$?");
160 
161       if (VarName.empty()) {
162         // Just a modifier, pass this into PrintSpecial.
163         Operands.push_back(AsmWriterOperand("PrintSpecial",
164                                             ~0U,
165                                             ~0U,
166                                             Modifier));
167       } else {
168         // Otherwise, normal operand.
169         unsigned OpNo = CGI.Operands.getOperandNamed(VarName);
170         CGIOperandList::OperandInfo OpInfo = CGI.Operands[OpNo];
171 
172         unsigned MIOp = OpInfo.MIOperandNo;
173         Operands.push_back(AsmWriterOperand(OpInfo.PrinterMethodName,
174                                             OpNo, MIOp, Modifier));
175       }
176       LastEmitted = VarEnd;
177     }
178   }
179 
180   Operands.push_back(AsmWriterOperand("return;",
181     AsmWriterOperand::isLiteralStatementOperand));
182 }
183 
184 /// MatchesAllButOneOp - If this instruction is exactly identical to the
185 /// specified instruction except for one differing operand, return the differing
186 /// operand number.  If more than one operand mismatches, return ~1, otherwise
187 /// if the instructions are identical return ~0.
188 unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
189   if (Operands.size() != Other.Operands.size()) return ~1;
190 
191   unsigned MismatchOperand = ~0U;
192   for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
193     if (Operands[i] != Other.Operands[i]) {
194       if (MismatchOperand != ~0U)  // Already have one mismatch?
195         return ~1U;
196       MismatchOperand = i;
197     }
198   }
199   return MismatchOperand;
200 }
201