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;
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
95    // '{' must immediately follow '~'.
96    if (I != E && *I != '{')
97      return true;
98  } else if (*I == '=') {
99    ++I;
100    Type = isOutput;
101  }
102
103  if (*I == '*') {
104    isIndirect = true;
105    ++I;
106  }
107
108  if (I == E) return true;  // Just a prefix, like "==" or "~".
109
110  // Parse the modifiers.
111  bool DoneWithModifiers = false;
112  while (!DoneWithModifiers) {
113    switch (*I) {
114    default:
115      DoneWithModifiers = true;
116      break;
117    case '&':     // Early clobber.
118      if (Type != isOutput ||      // Cannot early clobber anything but output.
119          isEarlyClobber)          // Reject &&&&&&
120        return true;
121      isEarlyClobber = true;
122      break;
123    case '%':     // Commutative.
124      if (Type == isClobber ||     // Cannot commute clobbers.
125          isCommutative)           // Reject %%%%%
126        return true;
127      isCommutative = true;
128      break;
129    case '#':     // Comment.
130    case '*':     // Register preferencing.
131      return true;     // Not supported.
132    }
133
134    if (!DoneWithModifiers) {
135      ++I;
136      if (I == E) return true;   // Just prefixes and modifiers!
137    }
138  }
139
140  // Parse the various constraints.
141  while (I != E) {
142    if (*I == '{') {   // Physical register reference.
143      // Find the end of the register name.
144      StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
145      if (ConstraintEnd == E) return true;  // "{foo"
146      pCodes->push_back(std::string(I, ConstraintEnd+1));
147      I = ConstraintEnd+1;
148    } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
149      // Maximal munch numbers.
150      StringRef::iterator NumStart = I;
151      while (I != E && isdigit(static_cast<unsigned char>(*I)))
152        ++I;
153      pCodes->push_back(std::string(NumStart, I));
154      unsigned N = atoi(pCodes->back().c_str());
155      // Check that this is a valid matching constraint!
156      if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
157          Type != isInput)
158        return true;  // Invalid constraint number.
159
160      // If Operand N already has a matching input, reject this.  An output
161      // can't be constrained to the same value as multiple inputs.
162      if (isMultipleAlternative) {
163        InlineAsm::SubConstraintInfo &scInfo =
164          ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
165        if (scInfo.MatchingInput != -1)
166          return true;
167        // Note that operand #n has a matching input.
168        scInfo.MatchingInput = ConstraintsSoFar.size();
169      } else {
170        if (ConstraintsSoFar[N].hasMatchingInput() &&
171            (size_t)ConstraintsSoFar[N].MatchingInput !=
172                ConstraintsSoFar.size())
173          return true;
174        // Note that operand #n has a matching input.
175        ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
176        }
177    } else if (*I == '|') {
178      multipleAlternativeIndex++;
179      pCodes = &multipleAlternatives[multipleAlternativeIndex].Codes;
180      ++I;
181    } else if (*I == '^') {
182      // Multi-letter constraint
183      // FIXME: For now assuming these are 2-character constraints.
184      pCodes->push_back(std::string(I+1, I+3));
185      I += 3;
186    } else {
187      // Single letter constraint.
188      pCodes->push_back(std::string(I, I+1));
189      ++I;
190    }
191  }
192
193  return false;
194}
195
196/// selectAlternative - Point this constraint to the alternative constraint
197/// indicated by the index.
198void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
199  if (index < multipleAlternatives.size()) {
200    currentAlternativeIndex = index;
201    InlineAsm::SubConstraintInfo &scInfo =
202      multipleAlternatives[currentAlternativeIndex];
203    MatchingInput = scInfo.MatchingInput;
204    Codes = scInfo.Codes;
205  }
206}
207
208InlineAsm::ConstraintInfoVector
209InlineAsm::ParseConstraints(StringRef Constraints) {
210  ConstraintInfoVector Result;
211
212  // Scan the constraints string.
213  for (StringRef::iterator I = Constraints.begin(),
214         E = Constraints.end(); I != E; ) {
215    ConstraintInfo Info;
216
217    // Find the end of this constraint.
218    StringRef::iterator ConstraintEnd = std::find(I, E, ',');
219
220    if (ConstraintEnd == I ||  // Empty constraint like ",,"
221        Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
222      Result.clear();          // Erroneous constraint?
223      break;
224    }
225
226    Result.push_back(Info);
227
228    // ConstraintEnd may be either the next comma or the end of the string.  In
229    // the former case, we skip the comma.
230    I = ConstraintEnd;
231    if (I != E) {
232      ++I;
233      if (I == E) {
234        Result.clear();
235        break;
236      } // 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 || STy->getNumElements() != NumOutputs)
287      return false;
288    break;
289  }
290
291  if (Ty->getNumParams() != NumInputs) return false;
292  return true;
293}
294
295