AsmWriterEmitter.cpp revision 953c6fe11277c2511744440f5d8d90aca1354e18 
1//===- AsmWriterEmitter.cpp - Generate an assembly writer -----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This tablegen backend is emits an assembly printer for the current target.
11// Note that this is currently fairly skeletal, but will grow over time.
12//
13//===----------------------------------------------------------------------===//
14
15#include "AsmWriterEmitter.h"
16#include "CodeGenTarget.h"
17#include "Record.h"
18#include <ostream>
19using namespace llvm;
20
21static bool isIdentChar(char C) {
22  return (C >= 'a' && C <= 'z') ||
23         (C >= 'A' && C <= 'Z') ||
24         (C >= '0' && C <= '9') ||
25         C == '_';
26}
27
28void AsmWriterEmitter::run(std::ostream &O) {
29  EmitSourceFileHeader("Assembly Writer Source Fragment", O);
30  O << "namespace llvm {\n\n";
31
32  CodeGenTarget Target;
33  Record *AsmWriter = Target.getAsmWriter();
34  std::string ClassName = AsmWriter->getValueAsString("AsmWriterClassName");
35  unsigned Variant = AsmWriter->getValueAsInt("Variant");
36
37  O <<
38  "/// printInstruction - This method is automatically generated by tablegen\n"
39  "/// from the instruction set description.  This method returns true if the\n"
40  "/// machine instruction was sufficiently described to print it, otherwise\n"
41  "/// it returns false.\n"
42    "bool " << Target.getName() << ClassName
43            << "::printInstruction(const MachineInstr *MI) {\n";
44  O << "  switch (MI->getOpcode()) {\n"
45       "  default: return false;\n";
46
47  std::string Namespace = Target.inst_begin()->second.Namespace;
48
49  bool inVariant = false;  // True if we are inside a {.|.|.} region.
50
51  for (CodeGenTarget::inst_iterator I = Target.inst_begin(),
52         E = Target.inst_end(); I != E; ++I)
53    if (!I->second.AsmString.empty()) {
54      const std::string &AsmString = I->second.AsmString;
55      O << "  case " << Namespace << "::" << I->first << ": O ";
56
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          // TODO: this should eventually handle escaping.
66          O << " << \"" << std::string(AsmString.begin()+LastEmitted,
67                                       AsmString.begin()+DollarPos) << "\"";
68          LastEmitted = DollarPos;
69        } else if (AsmString[DollarPos] == '{') {
70          if (inVariant)
71            throw "Nested variants found for instruction '" + I->first + "'!";
72          LastEmitted = DollarPos+1;
73          inVariant = true;   // We are now inside of the variant!
74          for (unsigned i = 0; i != Variant; ++i) {
75            // Skip over all of the text for an irrelevant variant here.  The
76            // next variant starts at |, or there may not be text for this
77            // variant if we see a }.
78            std::string::size_type NP =
79              AsmString.find_first_of("|}", LastEmitted);
80            if (NP == std::string::npos)
81              throw "Incomplete variant for instruction '" + I->first + "'!";
82            LastEmitted = NP+1;
83            if (AsmString[NP] == '}') {
84              inVariant = false;        // No text for this variant.
85              break;
86            }
87          }
88        } else if (AsmString[DollarPos] == '|') {
89          if (!inVariant)
90            throw "'|' character found outside of a variant in instruction '"
91                  + I->first + "'!";
92          // Move to the end of variant list.
93          std::string::size_type NP = AsmString.find('}', LastEmitted);
94          if (NP == std::string::npos)
95            throw "Incomplete variant for instruction '" + I->first + "'!";
96          LastEmitted = NP+1;
97          inVariant = false;
98        } else if (AsmString[DollarPos] == '}') {
99          if (!inVariant)
100            throw "'}' character found outside of a variant in instruction '"
101                  + I->first + "'!";
102          LastEmitted = DollarPos+1;
103          inVariant = false;
104        } else if (DollarPos+1 != AsmString.size() &&
105                   AsmString[DollarPos+1] == '$') {
106          O << " << '$'";         // "$$" -> $
107        } else {
108          // Get the name of the variable.
109          // TODO: should eventually handle ${foo}bar as $foo
110          std::string::size_type VarEnd = DollarPos+1;
111          while (VarEnd < AsmString.size() && isIdentChar(AsmString[VarEnd]))
112            ++VarEnd;
113          std::string VarName(AsmString.begin()+DollarPos+1,
114                              AsmString.begin()+VarEnd);
115          if (VarName.empty())
116            throw "Stray '$' in '" + I->first +
117                  "' asm string, maybe you want $$?";
118          unsigned OpNo = I->second.getOperandNamed(VarName);
119
120          // If this is a two-address instruction and we are not accessing the
121          // 0th operand, remove an operand.
122          unsigned MIOp = I->second.OperandList[OpNo].MIOperandNo;
123          if (I->second.isTwoAddress && MIOp != 0) {
124            if (MIOp == 1)
125              throw "Should refer to operand #0 instead of #1 for two-address"
126                    " instruction '" + I->first + "'!";
127            --MIOp;
128          }
129
130          O << ";  " << I->second.OperandList[OpNo].PrinterMethodName
131            << "(MI, " << MIOp << ", MVT::"
132            << getName(I->second.OperandList[OpNo].Ty) << "); O ";
133          LastEmitted = VarEnd;
134        }
135      }
136
137      O << " << '\\n'; break;\n";
138    }
139
140  O << "  }\n"
141       "  return true;\n"
142       "}\n";
143  O << "} // End llvm namespace \n";
144}
145