InlineAsm.cpp revision 0b8c9a80f20772c3793201ab5b251d3520b9cea3 
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>
20using namespace llvm;
21
22// Implement the first virtual method in this class in this file so the
23// InlineAsm vtable is emitted here.
24InlineAsm::~InlineAsm() {
25}
26
27
28InlineAsm *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
37InlineAsm::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
50void InlineAsm::destroyConstant() {
51  getType()->getContext().pImpl->InlineAsms.remove(this);
52  delete this;
53}
54
55FunctionType *InlineAsm::getFunctionType() const {
56  return cast<FunctionType>(getType()->getElementType());
57}
58
59///Default constructor.
60InlineAsm::ConstraintInfo::ConstraintInfo() :
61  Type(isInput), isEarlyClobber(false),
62  MatchingInput(-1), isCommutative(false),
63  isIndirect(false), isMultipleAlternative(false),
64  currentAlternativeIndex(0) {
65}
66
67/// Copy constructor.
68InlineAsm::ConstraintInfo::ConstraintInfo(const ConstraintInfo &other) :
69  Type(other.Type), isEarlyClobber(other.isEarlyClobber),
70  MatchingInput(other.MatchingInput), isCommutative(other.isCommutative),
71  isIndirect(other.isIndirect), Codes(other.Codes),
72  isMultipleAlternative(other.isMultipleAlternative),
73  multipleAlternatives(other.multipleAlternatives),
74  currentAlternativeIndex(other.currentAlternativeIndex) {
75}
76
77/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
78/// fields in this structure.  If the constraint string is not understood,
79/// return true, otherwise return false.
80bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
81                     InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
82  StringRef::iterator I = Str.begin(), E = Str.end();
83  unsigned multipleAlternativeCount = Str.count('|') + 1;
84  unsigned multipleAlternativeIndex = 0;
85  ConstraintCodeVector *pCodes = &Codes;
86
87  // Initialize
88  isMultipleAlternative = (multipleAlternativeCount > 1 ? true : false);
89  if (isMultipleAlternative) {
90    multipleAlternatives.resize(multipleAlternativeCount);
91    pCodes = &multipleAlternatives[0].Codes;
92  }
93  Type = isInput;
94  isEarlyClobber = false;
95  MatchingInput = -1;
96  isCommutative = false;
97  isIndirect = false;
98  currentAlternativeIndex = 0;
99
100  // Parse prefixes.
101  if (*I == '~') {
102    Type = isClobber;
103    ++I;
104  } else if (*I == '=') {
105    ++I;
106    Type = isOutput;
107  }
108
109  if (*I == '*') {
110    isIndirect = true;
111    ++I;
112  }
113
114  if (I == E) return true;  // Just a prefix, like "==" or "~".
115
116  // Parse the modifiers.
117  bool DoneWithModifiers = false;
118  while (!DoneWithModifiers) {
119    switch (*I) {
120    default:
121      DoneWithModifiers = true;
122      break;
123    case '&':     // Early clobber.
124      if (Type != isOutput ||      // Cannot early clobber anything but output.
125          isEarlyClobber)          // Reject &&&&&&
126        return true;
127      isEarlyClobber = true;
128      break;
129    case '%':     // Commutative.
130      if (Type == isClobber ||     // Cannot commute clobbers.
131          isCommutative)           // Reject %%%%%
132        return true;
133      isCommutative = true;
134      break;
135    case '#':     // Comment.
136    case '*':     // Register preferencing.
137      return true;     // Not supported.
138    }
139
140    if (!DoneWithModifiers) {
141      ++I;
142      if (I == E) return true;   // Just prefixes and modifiers!
143    }
144  }
145
146  // Parse the various constraints.
147  while (I != E) {
148    if (*I == '{') {   // Physical register reference.
149      // Find the end of the register name.
150      StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
151      if (ConstraintEnd == E) return true;  // "{foo"
152      pCodes->push_back(std::string(I, ConstraintEnd+1));
153      I = ConstraintEnd+1;
154    } else if (isdigit(*I)) {     // Matching Constraint
155      // Maximal munch numbers.
156      StringRef::iterator NumStart = I;
157      while (I != E && isdigit(*I))
158        ++I;
159      pCodes->push_back(std::string(NumStart, I));
160      unsigned N = atoi(pCodes->back().c_str());
161      // Check that this is a valid matching constraint!
162      if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
163          Type != isInput)
164        return true;  // Invalid constraint number.
165
166      // If Operand N already has a matching input, reject this.  An output
167      // can't be constrained to the same value as multiple inputs.
168      if (isMultipleAlternative) {
169        InlineAsm::SubConstraintInfo &scInfo =
170          ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
171        if (scInfo.MatchingInput != -1)
172          return true;
173        // Note that operand #n has a matching input.
174        scInfo.MatchingInput = ConstraintsSoFar.size();
175      } else {
176        if (ConstraintsSoFar[N].hasMatchingInput())
177          return true;
178        // Note that operand #n has a matching input.
179        ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
180        }
181    } else if (*I == '|') {
182      multipleAlternativeIndex++;
183      pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
184      ++I;
185    } else if (*I == '^') {
186      // Multi-letter constraint
187      // FIXME: For now assuming these are 2-character constraints.
188      pCodes->push_back(std::string(I+1, I+3));
189      I += 3;
190    } else {
191      // Single letter constraint.
192      pCodes->push_back(std::string(I, I+1));
193      ++I;
194    }
195  }
196
197  return false;
198}
199
200/// selectAlternative - Point this constraint to the alternative constraint
201/// indicated by the index.
202void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
203  if (index < multipleAlternatives.size()) {
204    currentAlternativeIndex = index;
205    InlineAsm::SubConstraintInfo &scInfo =
206      multipleAlternatives[currentAlternativeIndex];
207    MatchingInput = scInfo.MatchingInput;
208    Codes = scInfo.Codes;
209  }
210}
211
212InlineAsm::ConstraintInfoVector
213InlineAsm::ParseConstraints(StringRef Constraints) {
214  ConstraintInfoVector Result;
215
216  // Scan the constraints string.
217  for (StringRef::iterator I = Constraints.begin(),
218         E = Constraints.end(); I != E; ) {
219    ConstraintInfo Info;
220
221    // Find the end of this constraint.
222    StringRef::iterator ConstraintEnd = std::find(I, E, ',');
223
224    if (ConstraintEnd == I ||  // Empty constraint like ",,"
225        Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
226      Result.clear();          // Erroneous constraint?
227      break;
228    }
229
230    Result.push_back(Info);
231
232    // ConstraintEnd may be either the next comma or the end of the string.  In
233    // the former case, we skip the comma.
234    I = ConstraintEnd;
235    if (I != E) {
236      ++I;
237      if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
238    }
239  }
240
241  return Result;
242}
243
244/// Verify - Verify that the specified constraint string is reasonable for the
245/// specified function type, and otherwise validate the constraint string.
246bool InlineAsm::Verify(FunctionType *Ty, StringRef ConstStr) {
247  if (Ty->isVarArg()) return false;
248
249  ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
250
251  // Error parsing constraints.
252  if (Constraints.empty() && !ConstStr.empty()) return false;
253
254  unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
255  unsigned NumIndirect = 0;
256
257  for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
258    switch (Constraints[i].Type) {
259    case InlineAsm::isOutput:
260      if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
261        return false;  // outputs before inputs and clobbers.
262      if (!Constraints[i].isIndirect) {
263        ++NumOutputs;
264        break;
265      }
266      ++NumIndirect;
267      // FALLTHROUGH for Indirect Outputs.
268    case InlineAsm::isInput:
269      if (NumClobbers) return false;               // inputs before clobbers.
270      ++NumInputs;
271      break;
272    case InlineAsm::isClobber:
273      ++NumClobbers;
274      break;
275    }
276  }
277
278  switch (NumOutputs) {
279  case 0:
280    if (!Ty->getReturnType()->isVoidTy()) return false;
281    break;
282  case 1:
283    if (Ty->getReturnType()->isStructTy()) return false;
284    break;
285  default:
286    StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
287    if (STy == 0 || STy->getNumElements() != NumOutputs)
288      return false;
289    break;
290  }
291
292  if (Ty->getNumParams() != NumInputs) return false;
293  return true;
294}
295
296