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   delete this;
  51 }
  52
  53 const FunctionType *InlineAsm::getFunctionType() const {
  54   return cast<FunctionType>(getType()->getElementType());
  55 }
  56
  57 /// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
  58 /// fields in this structure.  If the constraint string is not understood,
  59 /// return true, otherwise return false.
  60 bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
  61                      std::vector<InlineAsm::ConstraintInfo> &ConstraintsSoFar) {
  62   StringRef::iterator I = Str.begin(), E = Str.end();
  63
  64   // Initialize
  65   Type = isInput;
  66   isEarlyClobber = false;
  67   MatchingInput = -1;
  68   isCommutative = false;
  69   isIndirect = false;
  70
  71   // Parse prefixes.
  72   if (*I == '~') {
  73     Type = isClobber;
  74     ++I;
  75   } else if (*I == '=') {
  76     ++I;
  77     Type = isOutput;
  78   }
  79
  80   if (*I == '*') {
  81     isIndirect = true;
  82     ++I;
  83   }
  84
  85   if (I == E) return true;  // Just a prefix, like "==" or "~".
  86
  87   // Parse the modifiers.
  88   bool DoneWithModifiers = false;
  89   while (!DoneWithModifiers) {
  90     switch (*I) {
  91     default:
  92       DoneWithModifiers = true;
  93       break;
  94     case '&':     // Early clobber.
  95       if (Type != isOutput ||      // Cannot early clobber anything but output.
  96           isEarlyClobber)          // Reject &&&&&&
  97         return true;
  98       isEarlyClobber = true;
  99       break;
 100     case '%':     // Commutative.
 101       if (Type == isClobber ||     // Cannot commute clobbers.
 102           isCommutative)           // Reject %%%%%
 103         return true;
 104       isCommutative = true;
 105       break;
 106     case '#':     // Comment.
 107     case '*':     // Register preferencing.
 108       return true;     // Not supported.
 109     }
 110
 111     if (!DoneWithModifiers) {
 112       ++I;
 113       if (I == E) return true;   // Just prefixes and modifiers!
 114     }
 115   }
 116
 117   // Parse the various constraints.
 118   while (I != E) {
 119     if (*I == '{') {   // Physical register reference.
 120       // Find the end of the register name.
 121       StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
 122       if (ConstraintEnd == E) return true;  // "{foo"
 123       Codes.push_back(std::string(I, ConstraintEnd+1));
 124       I = ConstraintEnd+1;
 125     } else if (isdigit(*I)) {     // Matching Constraint
 126       // Maximal munch numbers.
 127       StringRef::iterator NumStart = I;
 128       while (I != E && isdigit(*I))
 129         ++I;
 130       Codes.push_back(std::string(NumStart, I));
 131       unsigned N = atoi(Codes.back().c_str());
 132       // Check that this is a valid matching constraint!
 133       if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
 134           Type != isInput)
 135         return true;  // Invalid constraint number.
 136
 137       // If Operand N already has a matching input, reject this.  An output
 138       // can't be constrained to the same value as multiple inputs.
 139       if (ConstraintsSoFar[N].hasMatchingInput())
 140         return true;
 141
 142       // Note that operand #n has a matching input.
 143       ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
 144     } else {
 145       // Single letter constraint.
 146       Codes.push_back(std::string(I, I+1));
 147       ++I;
 148     }
 149   }
 150
 151   return false;
 152 }
 153
 154 std::vector<InlineAsm::ConstraintInfo>
 155 InlineAsm::ParseConstraints(StringRef Constraints) {
 156   std::vector<ConstraintInfo> Result;
 157
 158   // Scan the constraints string.
 159   for (StringRef::iterator I = Constraints.begin(),
 160          E = Constraints.end(); I != E; ) {
 161     ConstraintInfo Info;
 162
 163     // Find the end of this constraint.
 164     StringRef::iterator ConstraintEnd = std::find(I, E, ',');
 165
 166     if (ConstraintEnd == I ||  // Empty constraint like ",,"
 167         Info.Parse(std::string(I, ConstraintEnd), Result)) {
 168       Result.clear();          // Erroneous constraint?
 169       break;
 170     }
 171
 172     Result.push_back(Info);
 173
 174     // ConstraintEnd may be either the next comma or the end of the string.  In
 175     // the former case, we skip the comma.
 176     I = ConstraintEnd;
 177     if (I != E) {
 178       ++I;
 179       if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
 180     }
 181   }
 182
 183   return Result;
 184 }
 185
 186
 187 /// Verify - Verify that the specified constraint string is reasonable for the
 188 /// specified function type, and otherwise validate the constraint string.
 189 bool InlineAsm::Verify(const FunctionType *Ty, StringRef ConstStr) {
 190   if (Ty->isVarArg()) return false;
 191
 192   std::vector<ConstraintInfo> Constraints = ParseConstraints(ConstStr);
 193
 194   // Error parsing constraints.
 195   if (Constraints.empty() && !ConstStr.empty()) return false;
 196
 197   unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
 198   unsigned NumIndirect = 0;
 199
 200   for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
 201     switch (Constraints[i].Type) {
 202     case InlineAsm::isOutput:
 203       if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
 204         return false;  // outputs before inputs and clobbers.
 205       if (!Constraints[i].isIndirect) {
 206         ++NumOutputs;
 207         break;
 208       }
 209       ++NumIndirect;
 210       // FALLTHROUGH for Indirect Outputs.
 211     case InlineAsm::isInput:
 212       if (NumClobbers) return false;               // inputs before clobbers.
 213       ++NumInputs;
 214       break;
 215     case InlineAsm::isClobber:
 216       ++NumClobbers;
 217       break;
 218     }
 219   }
 220
 221   switch (NumOutputs) {
 222   case 0:
 223     if (!Ty->getReturnType()->isVoidTy()) return false;
 224     break;
 225   case 1:
 226     if (Ty->getReturnType()->isStructTy()) return false;
 227     break;
 228   default:
 229     const StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
 230     if (STy == 0 || STy->getNumElements() != NumOutputs)
 231       return false;
 232     break;
 233   }
 234
 235   if (Ty->getNumParams() != NumInputs) return false;
 236   return true;
 237 }
 238