llvm/lib/IR/InlineAsm.cpp

   1 //===- InlineAsm.cpp - Implement the InlineAsm class ----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the InlineAsm class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/IR/InlineAsm.h"
  14 #include "ConstantsContext.h"
  15 #include "LLVMContextImpl.h"
  16 #include "llvm/ADT/StringRef.h"
  17 #include "llvm/IR/DerivedTypes.h"
  18 #include "llvm/IR/LLVMContext.h"
  19 #include "llvm/IR/Value.h"
  20 #include "llvm/Support/Casting.h"
  21 #include "llvm/Support/Compiler.h"
  22 #include <algorithm>
  23 #include <cassert>
  24 #include <cctype>
  25 #include <cstddef>
  26 #include <cstdlib>
  27
  28 using namespace llvm;
  29
  30 InlineAsm::InlineAsm(FunctionType *FTy, const std::string &asmString,
  31                      const std::string &constraints, bool hasSideEffects,
  32                      bool isAlignStack, AsmDialect asmDialect, bool canThrow)
  33     : Value(PointerType::getUnqual(FTy), Value::InlineAsmVal),
  34       AsmString(asmString), Constraints(constraints), FTy(FTy),
  35       HasSideEffects(hasSideEffects), IsAlignStack(isAlignStack),
  36       Dialect(asmDialect), CanThrow(canThrow) {
  37   // Do various checks on the constraint string and type.
  38   assert(Verify(getFunctionType(), constraints) &&
  39          "Function type not legal for constraints!");
  40 }
  41
  42 InlineAsm *InlineAsm::get(FunctionType *FTy, StringRef AsmString,
  43                           StringRef Constraints, bool hasSideEffects,
  44                           bool isAlignStack, AsmDialect asmDialect,
  45                           bool canThrow) {
  46   InlineAsmKeyType Key(AsmString, Constraints, FTy, hasSideEffects,
  47                        isAlignStack, asmDialect, canThrow);
  48   LLVMContextImpl *pImpl = FTy->getContext().pImpl;
  49   return pImpl->InlineAsms.getOrCreate(PointerType::getUnqual(FTy), Key);
  50 }
  51
  52 void InlineAsm::destroyConstant() {
  53   getType()->getContext().pImpl->InlineAsms.remove(this);
  54   delete this;
  55 }
  56
  57 FunctionType *InlineAsm::getFunctionType() const {
  58   return FTy;
  59 }
  60
  61 /// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
  62 /// fields in this structure.  If the constraint string is not understood,
  63 /// return true, otherwise return false.
  64 bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
  65                      InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
  66   StringRef::iterator I = Str.begin(), E = Str.end();
  67   unsigned multipleAlternativeCount = Str.count('|') + 1;
  68   unsigned multipleAlternativeIndex = 0;
  69   ConstraintCodeVector *pCodes = &Codes;
  70
  71   // Initialize
  72   isMultipleAlternative = multipleAlternativeCount > 1;
  73   if (isMultipleAlternative) {
  74     multipleAlternatives.resize(multipleAlternativeCount);
  75     pCodes = &multipleAlternatives[0].Codes;
  76   }
  77   Type = isInput;
  78   isEarlyClobber = false;
  79   MatchingInput = -1;
  80   isCommutative = false;
  81   isIndirect = false;
  82   currentAlternativeIndex = 0;
  83
  84   // Parse prefixes.
  85   if (*I == '~') {
  86     Type = isClobber;
  87     ++I;
  88
  89     // '{' must immediately follow '~'.
  90     if (I != E && *I != '{')
  91       return true;
  92   } else if (*I == '=') {
  93     ++I;
  94     Type = isOutput;
  95   }
  96
  97   if (*I == '*') {
  98     isIndirect = true;
  99     ++I;
 100   }
 101
 102   if (I == E) return true;  // Just a prefix, like "==" or "~".
 103
 104   // Parse the modifiers.
 105   bool DoneWithModifiers = false;
 106   while (!DoneWithModifiers) {
 107     switch (*I) {
 108     default:
 109       DoneWithModifiers = true;
 110       break;
 111     case '&':     // Early clobber.
 112       if (Type != isOutput ||      // Cannot early clobber anything but output.
 113           isEarlyClobber)          // Reject &&&&&&
 114         return true;
 115       isEarlyClobber = true;
 116       break;
 117     case '%':     // Commutative.
 118       if (Type == isClobber ||     // Cannot commute clobbers.
 119           isCommutative)           // Reject %%%%%
 120         return true;
 121       isCommutative = true;
 122       break;
 123     case '#':     // Comment.
 124     case '*':     // Register preferencing.
 125       return true;     // Not supported.
 126     }
 127
 128     if (!DoneWithModifiers) {
 129       ++I;
 130       if (I == E) return true;   // Just prefixes and modifiers!
 131     }
 132   }
 133
 134   // Parse the various constraints.
 135   while (I != E) {
 136     if (*I == '{') {   // Physical register reference.
 137       // Find the end of the register name.
 138       StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
 139       if (ConstraintEnd == E) return true;  // "{foo"
 140       pCodes->push_back(std::string(StringRef(I, ConstraintEnd + 1 - I)));
 141       I = ConstraintEnd+1;
 142     } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
 143       // Maximal munch numbers.
 144       StringRef::iterator NumStart = I;
 145       while (I != E && isdigit(static_cast<unsigned char>(*I)))
 146         ++I;
 147       pCodes->push_back(std::string(StringRef(NumStart, I - NumStart)));
 148       unsigned N = atoi(pCodes->back().c_str());
 149       // Check that this is a valid matching constraint!
 150       if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
 151           Type != isInput)
 152         return true;  // Invalid constraint number.
 153
 154       // If Operand N already has a matching input, reject this.  An output
 155       // can't be constrained to the same value as multiple inputs.
 156       if (isMultipleAlternative) {
 157         if (multipleAlternativeIndex >=
 158             ConstraintsSoFar[N].multipleAlternatives.size())
 159           return true;
 160         InlineAsm::SubConstraintInfo &scInfo =
 161           ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
 162         if (scInfo.MatchingInput != -1)
 163           return true;
 164         // Note that operand #n has a matching input.
 165         scInfo.MatchingInput = ConstraintsSoFar.size();
 166         assert(scInfo.MatchingInput >= 0);
 167       } else {
 168         if (ConstraintsSoFar[N].hasMatchingInput() &&
 169             (size_t)ConstraintsSoFar[N].MatchingInput !=
 170                 ConstraintsSoFar.size())
 171           return true;
 172         // Note that operand #n has a matching input.
 173         ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
 174         assert(ConstraintsSoFar[N].MatchingInput >= 0);
 175         }
 176     } else if (*I == '|') {
 177       multipleAlternativeIndex++;
 178       pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
 179       ++I;
 180     } else if (*I == '^') {
 181       // Multi-letter constraint
 182       // FIXME: For now assuming these are 2-character constraints.
 183       pCodes->push_back(std::string(StringRef(I + 1, 2)));
 184       I += 3;
 185     } else if (*I == '@') {
 186       // Multi-letter constraint
 187       ++I;
 188       unsigned char C = static_cast<unsigned char>(*I);
 189       assert(isdigit(C) && "Expected a digit!");
 190       int N = C - '0';
 191       assert(N > 0 && "Found a zero letter constraint!");
 192       ++I;
 193       pCodes->push_back(std::string(StringRef(I, N)));
 194       I += N;
 195     } else {
 196       // Single letter constraint.
 197       pCodes->push_back(std::string(StringRef(I, 1)));
 198       ++I;
 199     }
 200   }
 201
 202   return false;
 203 }
 204
 205 /// selectAlternative - Point this constraint to the alternative constraint
 206 /// indicated by the index.
 207 void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
 208   if (index < multipleAlternatives.size()) {
 209     currentAlternativeIndex = index;
 210     InlineAsm::SubConstraintInfo &scInfo =
 211       multipleAlternatives[currentAlternativeIndex];
 212     MatchingInput = scInfo.MatchingInput;
 213     Codes = scInfo.Codes;
 214   }
 215 }
 216
 217 InlineAsm::ConstraintInfoVector
 218 InlineAsm::ParseConstraints(StringRef Constraints) {
 219   ConstraintInfoVector Result;
 220
 221   // Scan the constraints string.
 222   for (StringRef::iterator I = Constraints.begin(),
 223          E = Constraints.end(); I != E; ) {
 224     ConstraintInfo Info;
 225
 226     // Find the end of this constraint.
 227     StringRef::iterator ConstraintEnd = std::find(I, E, ',');
 228
 229     if (ConstraintEnd == I ||  // Empty constraint like ",,"
 230         Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
 231       Result.clear();          // Erroneous constraint?
 232       break;
 233     }
 234
 235     Result.push_back(Info);
 236
 237     // ConstraintEnd may be either the next comma or the end of the string.  In
 238     // the former case, we skip the comma.
 239     I = ConstraintEnd;
 240     if (I != E) {
 241       ++I;
 242       if (I == E) {
 243         Result.clear();
 244         break;
 245       } // don't allow "xyz,"
 246     }
 247   }
 248
 249   return Result;
 250 }
 251
 252 /// Verify - Verify that the specified constraint string is reasonable for the
 253 /// specified function type, and otherwise validate the constraint string.
 254 bool InlineAsm::Verify(FunctionType *Ty, StringRef ConstStr) {
 255   if (Ty->isVarArg()) return false;
 256
 257   ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
 258
 259   // Error parsing constraints.
 260   if (Constraints.empty() && !ConstStr.empty()) return false;
 261
 262   unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
 263   unsigned NumIndirect = 0;
 264
 265   for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
 266     switch (Constraints[i].Type) {
 267     case InlineAsm::isOutput:
 268       if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
 269         return false;  // outputs before inputs and clobbers.
 270       if (!Constraints[i].isIndirect) {
 271         ++NumOutputs;
 272         break;
 273       }
 274       ++NumIndirect;
 275       LLVM_FALLTHROUGH; // We fall through for Indirect Outputs.
 276     case InlineAsm::isInput:
 277       if (NumClobbers) return false;               // inputs before clobbers.
 278       ++NumInputs;
 279       break;
 280     case InlineAsm::isClobber:
 281       ++NumClobbers;
 282       break;
 283     }
 284   }
 285
 286   switch (NumOutputs) {
 287   case 0:
 288     if (!Ty->getReturnType()->isVoidTy()) return false;
 289     break;
 290   case 1:
 291     if (Ty->getReturnType()->isStructTy()) return false;
 292     break;
 293   default:
 294     StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
 295     if (!STy || STy->getNumElements() != NumOutputs)
 296       return false;
 297     break;
 298   }
 299
 300   if (Ty->getNumParams() != NumInputs) return false;
 301   return true;
 302 }