InlineAsm.cpp revision e602f473062a91e6ac9aa17097de8b5cd75b0852 
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>
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) {
31  InlineAsmKeyType Key(AsmString, Constraints, hasSideEffects, isAlignStack);
32  LLVMContextImpl *pImpl = Ty->getContext().pImpl;
33  return pImpl->InlineAsms.getOrCreate(PointerType::getUnqual(Ty), Key);
34}
35
36InlineAsm::InlineAsm(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
49void InlineAsm::destroyConstant() {
50  getType()->getContext().pImpl->InlineAsms.remove(this);
51  delete this;
52}
53
54FunctionType *InlineAsm::getFunctionType() const {
55  return cast<FunctionType>(getType()->getElementType());
56}
57
58///Default constructor.
59InlineAsm::ConstraintInfo::ConstraintInfo() :
60  Type(isInput), isEarlyClobber(false),
61  MatchingInput(-1), isCommutative(false),
62  isIndirect(false), isMultipleAlternative(false),
63  currentAlternativeIndex(0) {
64}
65
66/// Copy constructor.
67InlineAsm::ConstraintInfo::ConstraintInfo(const ConstraintInfo &other) :
68  Type(other.Type), isEarlyClobber(other.isEarlyClobber),
69  MatchingInput(other.MatchingInput), isCommutative(other.isCommutative),
70  isIndirect(other.isIndirect), Codes(other.Codes),
71  isMultipleAlternative(other.isMultipleAlternative),
72  multipleAlternatives(other.multipleAlternatives),
73  currentAlternativeIndex(other.currentAlternativeIndex) {
74}
75
76/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
77/// fields in this structure.  If the constraint string is not understood,
78/// return true, otherwise return false.
79bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
80                     InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
81  StringRef::iterator I = Str.begin(), E = Str.end();
82  unsigned multipleAlternativeCount = Str.count('|') + 1;
83  unsigned multipleAlternativeIndex = 0;
84  ConstraintCodeVector *pCodes = &Codes;
85
86  // Initialize
87  isMultipleAlternative = (multipleAlternativeCount > 1 ? true : false);
88  if (isMultipleAlternative) {
89    multipleAlternatives.resize(multipleAlternativeCount);
90    pCodes = &multipleAlternatives[0].Codes;
91  }
92  Type = isInput;
93  isEarlyClobber = false;
94  MatchingInput = -1;
95  isCommutative = false;
96  isIndirect = false;
97  currentAlternativeIndex = 0;
98
99  // Parse prefixes.
100  if (*I == '~') {
101    Type = isClobber;
102    ++I;
103  } else if (*I == '=') {
104    ++I;
105    Type = isOutput;
106  }
107
108  if (*I == '*') {
109    isIndirect = true;
110    ++I;
111  }
112
113  if (I == E) return true;  // Just a prefix, like "==" or "~".
114
115  // Parse the modifiers.
116  bool DoneWithModifiers = false;
117  while (!DoneWithModifiers) {
118    switch (*I) {
119    default:
120      DoneWithModifiers = true;
121      break;
122    case '&':     // Early clobber.
123      if (Type != isOutput ||      // Cannot early clobber anything but output.
124          isEarlyClobber)          // Reject &&&&&&
125        return true;
126      isEarlyClobber = true;
127      break;
128    case '%':     // Commutative.
129      if (Type == isClobber ||     // Cannot commute clobbers.
130          isCommutative)           // Reject %%%%%
131        return true;
132      isCommutative = true;
133      break;
134    case '#':     // Comment.
135    case '*':     // Register preferencing.
136      return true;     // Not supported.
137    }
138
139    if (!DoneWithModifiers) {
140      ++I;
141      if (I == E) return true;   // Just prefixes and modifiers!
142    }
143  }
144
145  // Parse the various constraints.
146  while (I != E) {
147    if (*I == '{') {   // Physical register reference.
148      // Find the end of the register name.
149      StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
150      if (ConstraintEnd == E) return true;  // "{foo"
151      pCodes->push_back(std::string(I, ConstraintEnd+1));
152      I = ConstraintEnd+1;
153    } else if (isdigit(*I)) {     // Matching Constraint
154      // Maximal munch numbers.
155      StringRef::iterator NumStart = I;
156      while (I != E && isdigit(*I))
157        ++I;
158      pCodes->push_back(std::string(NumStart, I));
159      unsigned N = atoi(pCodes->back().c_str());
160      // Check that this is a valid matching constraint!
161      if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
162          Type != isInput)
163        return true;  // Invalid constraint number.
164
165      // If Operand N already has a matching input, reject this.  An output
166      // can't be constrained to the same value as multiple inputs.
167      if (isMultipleAlternative) {
168        InlineAsm::SubConstraintInfo &scInfo =
169          ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
170        if (scInfo.MatchingInput != -1)
171          return true;
172        // Note that operand #n has a matching input.
173        scInfo.MatchingInput = ConstraintsSoFar.size();
174      } else {
175        if (ConstraintsSoFar[N].hasMatchingInput())
176          return true;
177        // Note that operand #n has a matching input.
178        ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
179        }
180    } else if (*I == '|') {
181      multipleAlternativeIndex++;
182      pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
183      ++I;
184    } else if (*I == '^') {
185      // Multi-letter constraint
186      // FIXME: For now assuming these are 2-character constraints.
187      pCodes->push_back(std::string(I+1, I+3));
188      I += 3;
189    } else {
190      // Single letter constraint.
191      pCodes->push_back(std::string(I, I+1));
192      ++I;
193    }
194  }
195
196  return false;
197}
198
199/// selectAlternative - Point this constraint to the alternative constraint
200/// indicated by the index.
201void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
202  if (index < multipleAlternatives.size()) {
203    currentAlternativeIndex = index;
204    InlineAsm::SubConstraintInfo &scInfo =
205      multipleAlternatives[currentAlternativeIndex];
206    MatchingInput = scInfo.MatchingInput;
207    Codes = scInfo.Codes;
208  }
209}
210
211InlineAsm::ConstraintInfoVector
212InlineAsm::ParseConstraints(StringRef Constraints) {
213  ConstraintInfoVector Result;
214
215  // Scan the constraints string.
216  for (StringRef::iterator I = Constraints.begin(),
217         E = Constraints.end(); I != E; ) {
218    ConstraintInfo Info;
219
220    // Find the end of this constraint.
221    StringRef::iterator ConstraintEnd = std::find(I, E, ',');
222
223    if (ConstraintEnd == I ||  // Empty constraint like ",,"
224        Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
225      Result.clear();          // Erroneous constraint?
226      break;
227    }
228
229    Result.push_back(Info);
230
231    // ConstraintEnd may be either the next comma or the end of the string.  In
232    // the former case, we skip the comma.
233    I = ConstraintEnd;
234    if (I != E) {
235      ++I;
236      if (I == E) { Result.clear(); break; }    // don't allow "xyz,"
237    }
238  }
239
240  return Result;
241}
242
243/// Verify - Verify that the specified constraint string is reasonable for the
244/// specified function type, and otherwise validate the constraint string.
245bool InlineAsm::Verify(FunctionType *Ty, StringRef ConstStr) {
246  if (Ty->isVarArg()) return false;
247
248  ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
249
250  // Error parsing constraints.
251  if (Constraints.empty() && !ConstStr.empty()) return false;
252
253  unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
254  unsigned NumIndirect = 0;
255
256  for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
257    switch (Constraints[i].Type) {
258    case InlineAsm::isOutput:
259      if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0)
260        return false;  // outputs before inputs and clobbers.
261      if (!Constraints[i].isIndirect) {
262        ++NumOutputs;
263        break;
264      }
265      ++NumIndirect;
266      // FALLTHROUGH for Indirect Outputs.
267    case InlineAsm::isInput:
268      if (NumClobbers) return false;               // inputs before clobbers.
269      ++NumInputs;
270      break;
271    case InlineAsm::isClobber:
272      ++NumClobbers;
273      break;
274    }
275  }
276
277  switch (NumOutputs) {
278  case 0:
279    if (!Ty->getReturnType()->isVoidTy()) return false;
280    break;
281  case 1:
282    if (Ty->getReturnType()->isStructTy()) return false;
283    break;
284  default:
285    StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
286    if (STy == 0 || STy->getNumElements() != NumOutputs)
287      return false;
288    break;
289  }
290
291  if (Ty->getNumParams() != NumInputs) return false;
292  return true;
293}
294
295