InlineAsm.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
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/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
68/// fields in this structure.  If the constraint string is not understood,
69/// return true, otherwise return false.
70bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
71                     InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
72  StringRef::iterator I = Str.begin(), E = Str.end();
73  unsigned multipleAlternativeCount = Str.count('|') + 1;
74  unsigned multipleAlternativeIndex = 0;
75  ConstraintCodeVector *pCodes = &Codes;
76
77  // Initialize
78  isMultipleAlternative = (multipleAlternativeCount > 1 ? true : false);
79  if (isMultipleAlternative) {
80    multipleAlternatives.resize(multipleAlternativeCount);
81    pCodes = &multipleAlternatives[0].Codes;
82  }
83  Type = isInput;
84  isEarlyClobber = false;
85  MatchingInput = -1;
86  isCommutative = false;
87  isIndirect = false;
88  currentAlternativeIndex = 0;
89
90  // Parse prefixes.
91  if (*I == '~') {
92    Type = isClobber;
93    ++I;
94  } else if (*I == '=') {
95    ++I;
96    Type = isOutput;
97  }
98
99  if (*I == '*') {
100    isIndirect = true;
101    ++I;
102  }
103
104  if (I == E) return true;  // Just a prefix, like "==" or "~".
105
106  // Parse the modifiers.
107  bool DoneWithModifiers = false;
108  while (!DoneWithModifiers) {
109    switch (*I) {
110    default:
111      DoneWithModifiers = true;
112      break;
113    case '&':     // Early clobber.
114      if (Type != isOutput ||      // Cannot early clobber anything but output.
115          isEarlyClobber)          // Reject &&&&&&
116        return true;
117      isEarlyClobber = true;
118      break;
119    case '%':     // Commutative.
120      if (Type == isClobber ||     // Cannot commute clobbers.
121          isCommutative)           // Reject %%%%%
122        return true;
123      isCommutative = true;
124      break;
125    case '#':     // Comment.
126    case '*':     // Register preferencing.
127      return true;     // Not supported.
128    }
129
130    if (!DoneWithModifiers) {
131      ++I;
132      if (I == E) return true;   // Just prefixes and modifiers!
133    }
134  }
135
136  // Parse the various constraints.
137  while (I != E) {
138    if (*I == '{') {   // Physical register reference.
139      // Find the end of the register name.
140      StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
141      if (ConstraintEnd == E) return true;  // "{foo"
142      pCodes->push_back(std::string(I, ConstraintEnd+1));
143      I = ConstraintEnd+1;
144    } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
145      // Maximal munch numbers.
146      StringRef::iterator NumStart = I;
147      while (I != E && isdigit(static_cast<unsigned char>(*I)))
148        ++I;
149      pCodes->push_back(std::string(NumStart, I));
150      unsigned N = atoi(pCodes->back().c_str());
151      // Check that this is a valid matching constraint!
152      if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
153          Type != isInput)
154        return true;  // Invalid constraint number.
155
156      // If Operand N already has a matching input, reject this.  An output
157      // can't be constrained to the same value as multiple inputs.
158      if (isMultipleAlternative) {
159        InlineAsm::SubConstraintInfo &scInfo =
160          ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
161        if (scInfo.MatchingInput != -1)
162          return true;
163        // Note that operand #n has a matching input.
164        scInfo.MatchingInput = ConstraintsSoFar.size();
165      } else {
166        if (ConstraintsSoFar[N].hasMatchingInput())
167          return true;
168        // Note that operand #n has a matching input.
169        ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
170        }
171    } else if (*I == '|') {
172      multipleAlternativeIndex++;
173      pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
174      ++I;
175    } else if (*I == '^') {
176      // Multi-letter constraint
177      // FIXME: For now assuming these are 2-character constraints.
178      pCodes->push_back(std::string(I+1, I+3));
179      I += 3;
180    } else {
181      // Single letter constraint.
182      pCodes->push_back(std::string(I, I+1));
183      ++I;
184    }
185  }
186
187  return false;
188}
189
190/// selectAlternative - Point this constraint to the alternative constraint
191/// indicated by the index.
192void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
193  if (index < multipleAlternatives.size()) {
194    currentAlternativeIndex = index;
195    InlineAsm::SubConstraintInfo &scInfo =
196      multipleAlternatives[currentAlternativeIndex];
197    MatchingInput = scInfo.MatchingInput;
198    Codes = scInfo.Codes;
199  }
200}
201
202InlineAsm::ConstraintInfoVector
203InlineAsm::ParseConstraints(StringRef Constraints) {
204  ConstraintInfoVector Result;
205
206  // Scan the constraints string.
207  for (StringRef::iterator I = Constraints.begin(),
208         E = Constraints.end(); I != E; ) {
209    ConstraintInfo Info;
210
211    // Find the end of this constraint.
212    StringRef::iterator ConstraintEnd = std::find(I, E, ',');
213
214    if (ConstraintEnd == I ||  // Empty constraint like ",,"
215        Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
216      Result.clear();          // Erroneous constraint?
217      break;
218    }
219
220    Result.push_back(Info);
221
222    // ConstraintEnd may be either the next comma or the end of the string.  In
223    // the former case, we skip the comma.
224    I = ConstraintEnd;
225    if (I != E) {
226      ++I;
227      if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
228    }
229  }
230
231  return Result;
232}
233
234/// Verify - Verify that the specified constraint string is reasonable for the
235/// specified function type, and otherwise validate the constraint string.
236bool InlineAsm::Verify(FunctionType *Ty, StringRef ConstStr) {
237  if (Ty->isVarArg()) return false;
238
239  ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
240
241  // Error parsing constraints.
242  if (Constraints.empty() && !ConstStr.empty()) return false;
243
244  unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
245  unsigned NumIndirect = 0;
246
247  for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
248    switch (Constraints[i].Type) {
249    case InlineAsm::isOutput:
250      if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
251        return false;  // outputs before inputs and clobbers.
252      if (!Constraints[i].isIndirect) {
253        ++NumOutputs;
254        break;
255      }
256      ++NumIndirect;
257      // FALLTHROUGH for Indirect Outputs.
258    case InlineAsm::isInput:
259      if (NumClobbers) return false;               // inputs before clobbers.
260      ++NumInputs;
261      break;
262    case InlineAsm::isClobber:
263      ++NumClobbers;
264      break;
265    }
266  }
267
268  switch (NumOutputs) {
269  case 0:
270    if (!Ty->getReturnType()->isVoidTy()) return false;
271    break;
272  case 1:
273    if (Ty->getReturnType()->isStructTy()) return false;
274    break;
275  default:
276    StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
277    if (STy == 0 || STy->getNumElements() != NumOutputs)
278      return false;
279    break;
280  }
281
282  if (Ty->getNumParams() != NumInputs) return false;
283  return true;
284}
285
286