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 "Record.h"
17 #include "llvm/ADT/StringExtras.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() 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   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,
51                              unsigned Variant,
52                              int FirstOperandColumn,
53                              int OperandSpacing) {
54   this->CGI = &CGI;
55 
56   unsigned CurVariant = ~0U;  // ~0 if we are outside a {.|.|.} region, other #.
57 
58   // This is the number of tabs we've seen if we're doing columnar layout.
59   unsigned CurColumn = 0;
60 
61 
62   // NOTE: Any extensions to this code need to be mirrored in the
63   // AsmPrinter::printInlineAsm code that executes as compile time (assuming
64   // that inline asm strings should also get the new feature)!
65   const std::string &AsmString = CGI.AsmString;
66   std::string::size_type LastEmitted = 0;
67   while (LastEmitted != AsmString.size()) {
68     std::string::size_type DollarPos =
69     AsmString.find_first_of("${|}\\", LastEmitted);
70     if (DollarPos == std::string::npos) DollarPos = AsmString.size();
71 
72     // Emit a constant string fragment.
73 
74     if (DollarPos != LastEmitted) {
75       if (CurVariant == Variant || CurVariant == ~0U) {
76         for (; LastEmitted != DollarPos; ++LastEmitted)
77           switch (AsmString[LastEmitted]) {
78             case '\n':
79               AddLiteralString("\\n");
80               break;
81             case '\t':
82               // If the asm writer is not using a columnar layout, \t is not
83               // magic.
84               if (FirstOperandColumn == -1 || OperandSpacing == -1) {
85                 AddLiteralString("\\t");
86               } else {
87                 // We recognize a tab as an operand delimeter.
88                 unsigned DestColumn = FirstOperandColumn +
89                 CurColumn++ * OperandSpacing;
90                 Operands.push_back(
91                   AsmWriterOperand(
92                     "O.PadToColumn(" +
93                     utostr(DestColumn) + ");\n",
94                     AsmWriterOperand::isLiteralStatementOperand));
95               }
96               break;
97             case '"':
98               AddLiteralString("\\\"");
99               break;
100             case '\\':
101               AddLiteralString("\\\\");
102               break;
103             default:
104               AddLiteralString(std::string(1, AsmString[LastEmitted]));
105               break;
106           }
107       } else {
108         LastEmitted = DollarPos;
109       }
110     } else if (AsmString[DollarPos] == '\\') {
111       if (DollarPos+1 != AsmString.size() &&
112           (CurVariant == Variant || CurVariant == ~0U)) {
113         if (AsmString[DollarPos+1] == 'n') {
114           AddLiteralString("\\n");
115         } else if (AsmString[DollarPos+1] == 't') {
116           // If the asm writer is not using a columnar layout, \t is not
117           // magic.
118           if (FirstOperandColumn == -1 || OperandSpacing == -1) {
119             AddLiteralString("\\t");
120             break;
121           }
122 
123           // We recognize a tab as an operand delimeter.
124           unsigned DestColumn = FirstOperandColumn +
125           CurColumn++ * OperandSpacing;
126           Operands.push_back(
127             AsmWriterOperand("O.PadToColumn(" + utostr(DestColumn) + ");\n",
128                              AsmWriterOperand::isLiteralStatementOperand));
129           break;
130         } else if (std::string("${|}\\").find(AsmString[DollarPos+1])
131                    != std::string::npos) {
132           AddLiteralString(std::string(1, AsmString[DollarPos+1]));
133         } else {
134           throw "Non-supported escaped character found in instruction '" +
135           CGI.TheDef->getName() + "'!";
136         }
137         LastEmitted = DollarPos+2;
138         continue;
139       }
140     } else if (AsmString[DollarPos] == '{') {
141       if (CurVariant != ~0U)
142         throw "Nested variants found for instruction '" +
143         CGI.TheDef->getName() + "'!";
144       LastEmitted = DollarPos+1;
145       CurVariant = 0;   // We are now inside of the variant!
146     } else if (AsmString[DollarPos] == '|') {
147       if (CurVariant == ~0U)
148         throw "'|' character found outside of a variant in instruction '"
149         + CGI.TheDef->getName() + "'!";
150       ++CurVariant;
151       ++LastEmitted;
152     } else if (AsmString[DollarPos] == '}') {
153       if (CurVariant == ~0U)
154         throw "'}' character found outside of a variant in instruction '"
155         + CGI.TheDef->getName() + "'!";
156       ++LastEmitted;
157       CurVariant = ~0U;
158     } else if (DollarPos+1 != AsmString.size() &&
159                AsmString[DollarPos+1] == '$') {
160       if (CurVariant == Variant || CurVariant == ~0U) {
161         AddLiteralString("$");  // "$$" -> $
162       }
163       LastEmitted = DollarPos+2;
164     } else {
165       // Get the name of the variable.
166       std::string::size_type VarEnd = DollarPos+1;
167 
168       // handle ${foo}bar as $foo by detecting whether the character following
169       // the dollar sign is a curly brace.  If so, advance VarEnd and DollarPos
170       // so the variable name does not contain the leading curly brace.
171       bool hasCurlyBraces = false;
172       if (VarEnd < AsmString.size() && '{' == AsmString[VarEnd]) {
173         hasCurlyBraces = true;
174         ++DollarPos;
175         ++VarEnd;
176       }
177 
178       while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
179         ++VarEnd;
180       std::string VarName(AsmString.begin()+DollarPos+1,
181                           AsmString.begin()+VarEnd);
182 
183       // Modifier - Support ${foo:modifier} syntax, where "modifier" is passed
184       // into printOperand.  Also support ${:feature}, which is passed into
185       // PrintSpecial.
186       std::string Modifier;
187 
188       // In order to avoid starting the next string at the terminating curly
189       // brace, advance the end position past it if we found an opening curly
190       // brace.
191       if (hasCurlyBraces) {
192         if (VarEnd >= AsmString.size())
193           throw "Reached end of string before terminating curly brace in '"
194           + CGI.TheDef->getName() + "'";
195 
196         // Look for a modifier string.
197         if (AsmString[VarEnd] == ':') {
198           ++VarEnd;
199           if (VarEnd >= AsmString.size())
200             throw "Reached end of string before terminating curly brace in '"
201             + CGI.TheDef->getName() + "'";
202 
203           unsigned ModifierStart = VarEnd;
204           while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
205             ++VarEnd;
206           Modifier = std::string(AsmString.begin()+ModifierStart,
207                                  AsmString.begin()+VarEnd);
208           if (Modifier.empty())
209             throw "Bad operand modifier name in '"+ CGI.TheDef->getName() + "'";
210         }
211 
212         if (AsmString[VarEnd] != '}')
213           throw "Variable name beginning with '{' did not end with '}' in '"
214           + CGI.TheDef->getName() + "'";
215         ++VarEnd;
216       }
217       if (VarName.empty() && Modifier.empty())
218         throw "Stray '$' in '" + CGI.TheDef->getName() +
219         "' asm string, maybe you want $$?";
220 
221       if (VarName.empty()) {
222         // Just a modifier, pass this into PrintSpecial.
223         Operands.push_back(AsmWriterOperand("PrintSpecial",
224                                             ~0U,
225                                             ~0U,
226                                             Modifier));
227       } else {
228         // Otherwise, normal operand.
229         unsigned OpNo = CGI.getOperandNamed(VarName);
230         CodeGenInstruction::OperandInfo OpInfo = CGI.OperandList[OpNo];
231 
232         if (CurVariant == Variant || CurVariant == ~0U) {
233           unsigned MIOp = OpInfo.MIOperandNo;
234           Operands.push_back(AsmWriterOperand(OpInfo.PrinterMethodName,
235                                               OpNo,
236                                               MIOp,
237                                               Modifier));
238         }
239       }
240       LastEmitted = VarEnd;
241     }
242   }
243 
244   Operands.push_back(AsmWriterOperand("return;",
245     AsmWriterOperand::isLiteralStatementOperand));
246 }
247 
248 /// MatchesAllButOneOp - If this instruction is exactly identical to the
249 /// specified instruction except for one differing operand, return the differing
250 /// operand number.  If more than one operand mismatches, return ~1, otherwise
251 /// if the instructions are identical return ~0.
252 unsigned AsmWriterInst::MatchesAllButOneOp(const AsmWriterInst &Other)const{
253   if (Operands.size() != Other.Operands.size()) return ~1;
254 
255   unsigned MismatchOperand = ~0U;
256   for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
257     if (Operands[i] != Other.Operands[i]) {
258       if (MismatchOperand != ~0U)  // Already have one mismatch?
259         return ~1U;
260       else
261         MismatchOperand = i;
262     }
263   }
264   return MismatchOperand;
265 }
266