lib/VMCore/InlineAsm.cpp

   1 //===-- InlineAsm.cpp - Implement the InlineAsm class ---------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by Chris Lattner and is distributed under the
   6 // University of Illinois Open Source 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 "llvm/DerivedTypes.h"
  16 #include <algorithm>
  17 #include <cctype>
  18 using namespace llvm;
  19
  20 // Implement the first virtual method in this class in this file so the
  21 // InlineAsm vtable is emitted here.
  22 InlineAsm::~InlineAsm() {
  23 }
  24
  25
  26 // NOTE: when memoizing the function type, we have to be careful to handle the
  27 // case when the type gets refined.
  28
  29 InlineAsm *InlineAsm::get(const FunctionType *Ty, const std::string &AsmString,
  30                           const std::string &Constraints, bool hasSideEffects) {
  31   // FIXME: memoize!
  32   return new InlineAsm(Ty, AsmString, Constraints, hasSideEffects);
  33 }
  34
  35 InlineAsm::InlineAsm(const FunctionType *Ty, const std::string &asmString,
  36                      const std::string &constraints, bool hasSideEffects)
  37   : Value(PointerType::get(Ty), Value::InlineAsmVal), AsmString(asmString),
  38     Constraints(constraints), HasSideEffects(hasSideEffects) {
  39
  40   // Do various checks on the constraint string and type.
  41   assert(Verify(Ty, constraints) && "Function type not legal for constraints!");
  42 }
  43
  44 const FunctionType *InlineAsm::getFunctionType() const {
  45   return cast<FunctionType>(getType()->getElementType());
  46 }
  47
  48 /// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
  49 /// fields in this structure.  If the constraint string is not understood,
  50 /// return true, otherwise return false.
  51 bool InlineAsm::ConstraintInfo::Parse(const std::string &Str,
  52                      std::vector<InlineAsm::ConstraintInfo> &ConstraintsSoFar) {
  53   std::string::const_iterator I = Str.begin(), E = Str.end();
  54
  55   // Initialize
  56   Type = isInput;
  57   isEarlyClobber = false;
  58   hasMatchingInput = false;
  59   isCommutative = false;
  60   isIndirect = false;
  61
  62   // Parse prefixes.
  63   if (*I == '~') {
  64     Type = isClobber;
  65     ++I;
  66   } else if (*I == '=') {
  67     ++I;
  68     Type = isOutput;
  69   }
  70
  71   if (*I == '*') {
  72     isIndirect = true;
  73     ++I;
  74   }
  75
  76   if (I == E) return true;  // Just a prefix, like "==" or "~".
  77
  78   // Parse the modifiers.
  79   bool DoneWithModifiers = false;
  80   while (!DoneWithModifiers) {
  81     switch (*I) {
  82     default:
  83       DoneWithModifiers = true;
  84       break;
  85     case '&':     // Early clobber.
  86       if (Type != isOutput ||      // Cannot early clobber anything but output.
  87           isEarlyClobber)          // Reject &&&&&&
  88         return true;
  89       isEarlyClobber = true;
  90       break;
  91     case '%':     // Commutative.
  92       if (Type == isClobber ||     // Cannot commute clobbers.
  93           isCommutative)           // Reject %%%%%
  94         return true;
  95       isCommutative = true;
  96       break;
  97     case '#':     // Comment.
  98     case '*':     // Register preferencing.
  99       return true;     // Not supported.
 100     }
 101
 102     if (!DoneWithModifiers) {
 103       ++I;
 104       if (I == E) return true;   // Just prefixes and modifiers!
 105     }
 106   }
 107
 108   // Parse the various constraints.
 109   while (I != E) {
 110     if (*I == '{') {   // Physical register reference.
 111       // Find the end of the register name.
 112       std::string::const_iterator ConstraintEnd = std::find(I+1, E, '}');
 113       if (ConstraintEnd == E) return true;  // "{foo"
 114       Codes.push_back(std::string(I, ConstraintEnd+1));
 115       I = ConstraintEnd+1;
 116     } else if (isdigit(*I)) {     // Matching Constraint
 117       // Maximal munch numbers.
 118       std::string::const_iterator NumStart = I;
 119       while (I != E && isdigit(*I))
 120         ++I;
 121       Codes.push_back(std::string(NumStart, I));
 122       unsigned N = atoi(Codes.back().c_str());
 123       // Check that this is a valid matching constraint!
 124       if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
 125           Type != isInput)
 126         return true;  // Invalid constraint number.
 127
 128       // Note that operand #n has a matching input.
 129       ConstraintsSoFar[N].hasMatchingInput = true;
 130     } else {
 131       // Single letter constraint.
 132       Codes.push_back(std::string(I, I+1));
 133       ++I;
 134     }
 135   }
 136
 137   return false;
 138 }
 139
 140 std::vector<InlineAsm::ConstraintInfo>
 141 InlineAsm::ParseConstraints(const std::string &Constraints) {
 142   std::vector<ConstraintInfo> Result;
 143
 144   // Scan the constraints string.
 145   for (std::string::const_iterator I = Constraints.begin(),
 146        E = Constraints.end(); I != E; ) {
 147     ConstraintInfo Info;
 148
 149     // Find the end of this constraint.
 150     std::string::const_iterator ConstraintEnd = std::find(I, E, ',');
 151
 152     if (ConstraintEnd == I ||  // Empty constraint like ",,"
 153         Info.Parse(std::string(I, ConstraintEnd), Result)) {
 154       Result.clear();          // Erroneous constraint?
 155       break;
 156     }
 157
 158     Result.push_back(Info);
 159
 160     // ConstraintEnd may be either the next comma or the end of the string.  In
 161     // the former case, we skip the comma.
 162     I = ConstraintEnd;
 163     if (I != E) {
 164       ++I;
 165       if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
 166     }
 167   }
 168
 169   return Result;
 170 }
 171
 172
 173 /// Verify - Verify that the specified constraint string is reasonable for the
 174 /// specified function type, and otherwise validate the constraint string.
 175 bool InlineAsm::Verify(const FunctionType *Ty, const std::string &ConstStr) {
 176   if (Ty->isVarArg()) return false;
 177
 178   std::vector<ConstraintInfo> Constraints = ParseConstraints(ConstStr);
 179
 180   // Error parsing constraints.
 181   if (Constraints.empty() && !ConstStr.empty()) return false;
 182
 183   unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
 184
 185   for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
 186     switch (Constraints[i].Type) {
 187     case InlineAsm::isOutput:
 188       if (!Constraints[i].isIndirect) {
 189         if (NumInputs || NumClobbers) return false;  // outputs come first.
 190         ++NumOutputs;
 191         break;
 192       }
 193       // FALLTHROUGH for Indirect Outputs.
 194     case InlineAsm::isInput:
 195       if (NumClobbers) return false;               // inputs before clobbers.
 196       ++NumInputs;
 197       break;
 198     case InlineAsm::isClobber:
 199       ++NumClobbers;
 200       break;
 201     }
 202   }
 203
 204   if (NumOutputs > 1) return false;  // Only one result allowed so far.
 205
 206   if ((Ty->getReturnType() != Type::VoidTy) != NumOutputs)
 207     return false;   // NumOutputs = 1 iff has a result type.
 208
 209   if (Ty->getNumParams() != NumInputs) return false;
 210   return true;
 211 }
 212
 213 DEFINING_FILE_FOR(InlineAsm)