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1 //===- InlineAsm.cpp - Implement the InlineAsm class ----------------------===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8 //
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9 // This file implements the InlineAsm class.
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10 //
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11 //===----------------------------------------------------------------------===//
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12
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13 #include "llvm/IR/InlineAsm.h"
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14 #include "ConstantsContext.h"
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15 #include "LLVMContextImpl.h"
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16 #include "llvm/ADT/StringRef.h"
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17 #include "llvm/IR/DerivedTypes.h"
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18 #include "llvm/IR/LLVMContext.h"
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19 #include "llvm/IR/Value.h"
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20 #include "llvm/Support/Casting.h"
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21 #include "llvm/Support/Compiler.h"
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22 #include <algorithm>
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23 #include <cassert>
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24 #include <cctype>
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25 #include <cstddef>
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26 #include <cstdlib>
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27
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28 using namespace llvm;
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29
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30 InlineAsm::InlineAsm(FunctionType *FTy, const std::string &asmString,
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31 const std::string &constraints, bool hasSideEffects,
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32 bool isAlignStack, AsmDialect asmDialect)
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33 : Value(PointerType::getUnqual(FTy), Value::InlineAsmVal),
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34 AsmString(asmString), Constraints(constraints), FTy(FTy),
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35 HasSideEffects(hasSideEffects), IsAlignStack(isAlignStack),
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36 Dialect(asmDialect) {
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37 // Do various checks on the constraint string and type.
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38 assert(Verify(getFunctionType(), constraints) &&
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39 "Function type not legal for constraints!");
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40 }
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41
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42 InlineAsm *InlineAsm::get(FunctionType *FTy, StringRef AsmString,
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43 StringRef Constraints, bool hasSideEffects,
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44 bool isAlignStack, AsmDialect asmDialect) {
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45 InlineAsmKeyType Key(AsmString, Constraints, FTy, hasSideEffects,
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46 isAlignStack, asmDialect);
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47 LLVMContextImpl *pImpl = FTy->getContext().pImpl;
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48 return pImpl->InlineAsms.getOrCreate(PointerType::getUnqual(FTy), Key);
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49 }
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50
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51 void InlineAsm::destroyConstant() {
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52 getType()->getContext().pImpl->InlineAsms.remove(this);
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53 delete this;
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54 }
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55
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56 FunctionType *InlineAsm::getFunctionType() const {
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57 return FTy;
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58 }
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59
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60 /// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
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61 /// fields in this structure. If the constraint string is not understood,
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62 /// return true, otherwise return false.
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63 bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
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64 InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
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65 StringRef::iterator I = Str.begin(), E = Str.end();
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66 unsigned multipleAlternativeCount = Str.count('|') + 1;
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67 unsigned multipleAlternativeIndex = 0;
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68 ConstraintCodeVector *pCodes = &Codes;
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69
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70 // Initialize
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71 isMultipleAlternative = multipleAlternativeCount > 1;
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72 if (isMultipleAlternative) {
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73 multipleAlternatives.resize(multipleAlternativeCount);
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74 pCodes = &multipleAlternatives[0].Codes;
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75 }
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76 Type = isInput;
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77 isEarlyClobber = false;
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78 MatchingInput = -1;
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79 isCommutative = false;
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80 isIndirect = false;
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81 currentAlternativeIndex = 0;
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82
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83 // Parse prefixes.
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84 if (*I == '~') {
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85 Type = isClobber;
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86 ++I;
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87
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88 // '{' must immediately follow '~'.
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89 if (I != E && *I != '{')
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90 return true;
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91 } else if (*I == '=') {
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92 ++I;
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93 Type = isOutput;
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94 }
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95
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96 if (*I == '*') {
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97 isIndirect = true;
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98 ++I;
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99 }
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100
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101 if (I == E) return true; // Just a prefix, like "==" or "~".
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102
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103 // Parse the modifiers.
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104 bool DoneWithModifiers = false;
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105 while (!DoneWithModifiers) {
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106 switch (*I) {
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107 default:
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108 DoneWithModifiers = true;
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109 break;
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110 case '&': // Early clobber.
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111 if (Type != isOutput || // Cannot early clobber anything but output.
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112 isEarlyClobber) // Reject &&&&&&
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113 return true;
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114 isEarlyClobber = true;
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115 break;
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116 case '%': // Commutative.
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117 if (Type == isClobber || // Cannot commute clobbers.
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118 isCommutative) // Reject %%%%%
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119 return true;
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120 isCommutative = true;
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121 break;
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122 case '#': // Comment.
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123 case '*': // Register preferencing.
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124 return true; // Not supported.
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125 }
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126
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127 if (!DoneWithModifiers) {
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128 ++I;
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129 if (I == E) return true; // Just prefixes and modifiers!
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130 }
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131 }
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132
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133 // Parse the various constraints.
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134 while (I != E) {
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135 if (*I == '{') { // Physical register reference.
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136 // Find the end of the register name.
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137 StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
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138 if (ConstraintEnd == E) return true; // "{foo"
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139 pCodes->push_back(std::string(StringRef(I, ConstraintEnd + 1 - I)));
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140 I = ConstraintEnd+1;
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141 } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
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142 // Maximal munch numbers.
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143 StringRef::iterator NumStart = I;
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144 while (I != E && isdigit(static_cast<unsigned char>(*I)))
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145 ++I;
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146 pCodes->push_back(std::string(StringRef(NumStart, I - NumStart)));
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147 unsigned N = atoi(pCodes->back().c_str());
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148 // Check that this is a valid matching constraint!
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149 if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
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150 Type != isInput)
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151 return true; // Invalid constraint number.
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152
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153 // If Operand N already has a matching input, reject this. An output
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154 // can't be constrained to the same value as multiple inputs.
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155 if (isMultipleAlternative) {
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156 if (multipleAlternativeIndex >=
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157 ConstraintsSoFar[N].multipleAlternatives.size())
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158 return true;
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159 InlineAsm::SubConstraintInfo &scInfo =
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160 ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
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161 if (scInfo.MatchingInput != -1)
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162 return true;
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163 // Note that operand #n has a matching input.
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164 scInfo.MatchingInput = ConstraintsSoFar.size();
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165 assert(scInfo.MatchingInput >= 0);
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166 } else {
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167 if (ConstraintsSoFar[N].hasMatchingInput() &&
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168 (size_t)ConstraintsSoFar[N].MatchingInput !=
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169 ConstraintsSoFar.size())
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170 return true;
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171 // Note that operand #n has a matching input.
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172 ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
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173 assert(ConstraintsSoFar[N].MatchingInput >= 0);
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174 }
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175 } else if (*I == '|') {
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176 multipleAlternativeIndex++;
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177 pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
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178 ++I;
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179 } else if (*I == '^') {
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180 // Multi-letter constraint
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181 // FIXME: For now assuming these are 2-character constraints.
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182 pCodes->push_back(std::string(StringRef(I + 1, 2)));
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183 I += 3;
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184 } else if (*I == '@') {
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185 // Multi-letter constraint
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186 ++I;
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187 unsigned char C = static_cast<unsigned char>(*I);
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188 assert(isdigit(C) && "Expected a digit!");
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189 int N = C - '0';
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190 assert(N > 0 && "Found a zero letter constraint!");
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191 ++I;
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192 pCodes->push_back(std::string(StringRef(I, N)));
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193 I += N;
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194 } else {
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195 // Single letter constraint.
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196 pCodes->push_back(std::string(StringRef(I, 1)));
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197 ++I;
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198 }
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199 }
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200
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201 return false;
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202 }
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203
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204 /// selectAlternative - Point this constraint to the alternative constraint
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205 /// indicated by the index.
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206 void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
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207 if (index < multipleAlternatives.size()) {
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208 currentAlternativeIndex = index;
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209 InlineAsm::SubConstraintInfo &scInfo =
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210 multipleAlternatives[currentAlternativeIndex];
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211 MatchingInput = scInfo.MatchingInput;
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212 Codes = scInfo.Codes;
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213 }
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214 }
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215
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216 InlineAsm::ConstraintInfoVector
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217 InlineAsm::ParseConstraints(StringRef Constraints) {
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218 ConstraintInfoVector Result;
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219
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220 // Scan the constraints string.
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221 for (StringRef::iterator I = Constraints.begin(),
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222 E = Constraints.end(); I != E; ) {
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223 ConstraintInfo Info;
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224
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225 // Find the end of this constraint.
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226 StringRef::iterator ConstraintEnd = std::find(I, E, ',');
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227
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228 if (ConstraintEnd == I || // Empty constraint like ",,"
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229 Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
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230 Result.clear(); // Erroneous constraint?
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231 break;
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232 }
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233
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234 Result.push_back(Info);
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235
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236 // ConstraintEnd may be either the next comma or the end of the string. In
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237 // the former case, we skip the comma.
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238 I = ConstraintEnd;
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239 if (I != E) {
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240 ++I;
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241 if (I == E) {
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242 Result.clear();
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243 break;
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244 } // don't allow "xyz,"
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245 }
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246 }
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247
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248 return Result;
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249 }
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250
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251 /// Verify - Verify that the specified constraint string is reasonable for the
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252 /// specified function type, and otherwise validate the constraint string.
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253 bool InlineAsm::Verify(FunctionType *Ty, StringRef ConstStr) {
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254 if (Ty->isVarArg()) return false;
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255
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256 ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
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257
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258 // Error parsing constraints.
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259 if (Constraints.empty() && !ConstStr.empty()) return false;
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260
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261 unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
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262 unsigned NumIndirect = 0;
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263
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264 for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
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265 switch (Constraints[i].Type) {
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266 case InlineAsm::isOutput:
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267 if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
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268 return false; // outputs before inputs and clobbers.
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269 if (!Constraints[i].isIndirect) {
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270 ++NumOutputs;
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271 break;
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272 }
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273 ++NumIndirect;
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274 LLVM_FALLTHROUGH; // We fall through for Indirect Outputs.
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275 case InlineAsm::isInput:
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276 if (NumClobbers) return false; // inputs before clobbers.
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277 ++NumInputs;
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278 break;
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279 case InlineAsm::isClobber:
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280 ++NumClobbers;
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281 break;
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282 }
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283 }
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284
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285 switch (NumOutputs) {
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286 case 0:
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287 if (!Ty->getReturnType()->isVoidTy()) return false;
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288 break;
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289 case 1:
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290 if (Ty->getReturnType()->isStructTy()) return false;
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291 break;
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292 default:
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293 StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
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294 if (!STy || STy->getNumElements() != NumOutputs)
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295 return false;
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296 break;
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297 }
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298
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299 if (Ty->getNumParams() != NumInputs) return false;
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300 return true;
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301 }
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