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