src/llvm/lib/IR/InlineAsm.cpp

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