1 //===- InlineAsm.cpp - Implement the InlineAsm class ----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the InlineAsm class.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/IR/InlineAsm.h"
14 #include "ConstantsContext.h"
15 #include "LLVMContextImpl.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/IR/DerivedTypes.h"
18 #include "llvm/IR/LLVMContext.h"
19 #include "llvm/IR/Value.h"
20 #include "llvm/Support/Casting.h"
21 #include "llvm/Support/Compiler.h"
22 #include "llvm/Support/Errc.h"
23 #include <algorithm>
24 #include <cassert>
25 #include <cctype>
26 #include <cstdlib>
27
28 using namespace llvm;
29
InlineAsm(FunctionType * FTy,const std::string & asmString,const std::string & constraints,bool hasSideEffects,bool isAlignStack,AsmDialect asmDialect,bool canThrow)30 InlineAsm::InlineAsm(FunctionType *FTy, const std::string &asmString,
31 const std::string &constraints, bool hasSideEffects,
32 bool isAlignStack, AsmDialect asmDialect, bool canThrow)
33 : Value(PointerType::getUnqual(FTy), Value::InlineAsmVal),
34 AsmString(asmString), Constraints(constraints), FTy(FTy),
35 HasSideEffects(hasSideEffects), IsAlignStack(isAlignStack),
36 Dialect(asmDialect), CanThrow(canThrow) {
37 #ifndef NDEBUG
38 // Do various checks on the constraint string and type.
39 cantFail(verify(getFunctionType(), constraints));
40 #endif
41 }
42
get(FunctionType * FTy,StringRef AsmString,StringRef Constraints,bool hasSideEffects,bool isAlignStack,AsmDialect asmDialect,bool canThrow)43 InlineAsm *InlineAsm::get(FunctionType *FTy, StringRef AsmString,
44 StringRef Constraints, bool hasSideEffects,
45 bool isAlignStack, AsmDialect asmDialect,
46 bool canThrow) {
47 InlineAsmKeyType Key(AsmString, Constraints, FTy, hasSideEffects,
48 isAlignStack, asmDialect, canThrow);
49 LLVMContextImpl *pImpl = FTy->getContext().pImpl;
50 return pImpl->InlineAsms.getOrCreate(PointerType::getUnqual(FTy), Key);
51 }
52
destroyConstant()53 void InlineAsm::destroyConstant() {
54 getType()->getContext().pImpl->InlineAsms.remove(this);
55 delete this;
56 }
57
getFunctionType() const58 FunctionType *InlineAsm::getFunctionType() const {
59 return FTy;
60 }
61
62 /// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
63 /// fields in this structure. If the constraint string is not understood,
64 /// return true, otherwise return false.
Parse(StringRef Str,InlineAsm::ConstraintInfoVector & ConstraintsSoFar)65 bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
66 InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
67 StringRef::iterator I = Str.begin(), E = Str.end();
68 unsigned multipleAlternativeCount = Str.count('|') + 1;
69 unsigned multipleAlternativeIndex = 0;
70 ConstraintCodeVector *pCodes = &Codes;
71
72 // Initialize
73 isMultipleAlternative = multipleAlternativeCount > 1;
74 if (isMultipleAlternative) {
75 multipleAlternatives.resize(multipleAlternativeCount);
76 pCodes = &multipleAlternatives[0].Codes;
77 }
78 Type = isInput;
79 isEarlyClobber = false;
80 MatchingInput = -1;
81 isCommutative = false;
82 isIndirect = false;
83 currentAlternativeIndex = 0;
84
85 // Parse prefixes.
86 if (*I == '~') {
87 Type = isClobber;
88 ++I;
89
90 // '{' must immediately follow '~'.
91 if (I != E && *I != '{')
92 return true;
93 } else if (*I == '=') {
94 ++I;
95 Type = isOutput;
96 } else if (*I == '!') {
97 ++I;
98 Type = isLabel;
99 }
100
101 if (*I == '*') {
102 isIndirect = true;
103 ++I;
104 }
105
106 if (I == E) return true; // Just a prefix, like "==" or "~".
107
108 // Parse the modifiers.
109 bool DoneWithModifiers = false;
110 while (!DoneWithModifiers) {
111 switch (*I) {
112 default:
113 DoneWithModifiers = true;
114 break;
115 case '&': // Early clobber.
116 if (Type != isOutput || // Cannot early clobber anything but output.
117 isEarlyClobber) // Reject &&&&&&
118 return true;
119 isEarlyClobber = true;
120 break;
121 case '%': // Commutative.
122 if (Type == isClobber || // Cannot commute clobbers.
123 isCommutative) // Reject %%%%%
124 return true;
125 isCommutative = true;
126 break;
127 case '#': // Comment.
128 case '*': // Register preferencing.
129 return true; // Not supported.
130 }
131
132 if (!DoneWithModifiers) {
133 ++I;
134 if (I == E) return true; // Just prefixes and modifiers!
135 }
136 }
137
138 // Parse the various constraints.
139 while (I != E) {
140 if (*I == '{') { // Physical register reference.
141 // Find the end of the register name.
142 StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
143 if (ConstraintEnd == E) return true; // "{foo"
144 pCodes->push_back(std::string(StringRef(I, ConstraintEnd + 1 - I)));
145 I = ConstraintEnd+1;
146 } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
147 // Maximal munch numbers.
148 StringRef::iterator NumStart = I;
149 while (I != E && isdigit(static_cast<unsigned char>(*I)))
150 ++I;
151 pCodes->push_back(std::string(StringRef(NumStart, I - NumStart)));
152 unsigned N = atoi(pCodes->back().c_str());
153 // Check that this is a valid matching constraint!
154 if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
155 Type != isInput)
156 return true; // Invalid constraint number.
157
158 // If Operand N already has a matching input, reject this. An output
159 // can't be constrained to the same value as multiple inputs.
160 if (isMultipleAlternative) {
161 if (multipleAlternativeIndex >=
162 ConstraintsSoFar[N].multipleAlternatives.size())
163 return true;
164 InlineAsm::SubConstraintInfo &scInfo =
165 ConstraintsSoFar[N].multipleAlternatives[multipleAlternativeIndex];
166 if (scInfo.MatchingInput != -1)
167 return true;
168 // Note that operand #n has a matching input.
169 scInfo.MatchingInput = ConstraintsSoFar.size();
170 assert(scInfo.MatchingInput >= 0);
171 } else {
172 if (ConstraintsSoFar[N].hasMatchingInput() &&
173 (size_t)ConstraintsSoFar[N].MatchingInput !=
174 ConstraintsSoFar.size())
175 return true;
176 // Note that operand #n has a matching input.
177 ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
178 assert(ConstraintsSoFar[N].MatchingInput >= 0);
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(StringRef(I + 1, 2)));
188 I += 3;
189 } else if (*I == '@') {
190 // Multi-letter constraint
191 ++I;
192 unsigned char C = static_cast<unsigned char>(*I);
193 assert(isdigit(C) && "Expected a digit!");
194 int N = C - '0';
195 assert(N > 0 && "Found a zero letter constraint!");
196 ++I;
197 pCodes->push_back(std::string(StringRef(I, N)));
198 I += N;
199 } else {
200 // Single letter constraint.
201 pCodes->push_back(std::string(StringRef(I, 1)));
202 ++I;
203 }
204 }
205
206 return false;
207 }
208
209 /// selectAlternative - Point this constraint to the alternative constraint
210 /// indicated by the index.
selectAlternative(unsigned index)211 void InlineAsm::ConstraintInfo::selectAlternative(unsigned index) {
212 if (index < multipleAlternatives.size()) {
213 currentAlternativeIndex = index;
214 InlineAsm::SubConstraintInfo &scInfo =
215 multipleAlternatives[currentAlternativeIndex];
216 MatchingInput = scInfo.MatchingInput;
217 Codes = scInfo.Codes;
218 }
219 }
220
221 InlineAsm::ConstraintInfoVector
ParseConstraints(StringRef Constraints)222 InlineAsm::ParseConstraints(StringRef Constraints) {
223 ConstraintInfoVector Result;
224
225 // Scan the constraints string.
226 for (StringRef::iterator I = Constraints.begin(),
227 E = Constraints.end(); I != E; ) {
228 ConstraintInfo Info;
229
230 // Find the end of this constraint.
231 StringRef::iterator ConstraintEnd = std::find(I, E, ',');
232
233 if (ConstraintEnd == I || // Empty constraint like ",,"
234 Info.Parse(StringRef(I, ConstraintEnd-I), Result)) {
235 Result.clear(); // Erroneous constraint?
236 break;
237 }
238
239 Result.push_back(Info);
240
241 // ConstraintEnd may be either the next comma or the end of the string. In
242 // the former case, we skip the comma.
243 I = ConstraintEnd;
244 if (I != E) {
245 ++I;
246 if (I == E) {
247 Result.clear();
248 break;
249 } // don't allow "xyz,"
250 }
251 }
252
253 return Result;
254 }
255
makeStringError(const char * Msg)256 static Error makeStringError(const char *Msg) {
257 return createStringError(errc::invalid_argument, Msg);
258 }
259
verify(FunctionType * Ty,StringRef ConstStr)260 Error InlineAsm::verify(FunctionType *Ty, StringRef ConstStr) {
261 if (Ty->isVarArg())
262 return makeStringError("inline asm cannot be variadic");
263
264 ConstraintInfoVector Constraints = ParseConstraints(ConstStr);
265
266 // Error parsing constraints.
267 if (Constraints.empty() && !ConstStr.empty())
268 return makeStringError("failed to parse constraints");
269
270 unsigned NumOutputs = 0, NumInputs = 0, NumClobbers = 0;
271 unsigned NumIndirect = 0, NumLabels = 0;
272
273 for (const ConstraintInfo &Constraint : Constraints) {
274 switch (Constraint.Type) {
275 case InlineAsm::isOutput:
276 if ((NumInputs-NumIndirect) != 0 || NumClobbers != 0 || NumLabels != 0)
277 return makeStringError("output constraint occurs after input, "
278 "clobber or label constraint");
279
280 if (!Constraint.isIndirect) {
281 ++NumOutputs;
282 break;
283 }
284 ++NumIndirect;
285 LLVM_FALLTHROUGH; // We fall through for Indirect Outputs.
286 case InlineAsm::isInput:
287 if (NumClobbers)
288 return makeStringError("input constraint occurs after clobber "
289 "constraint");
290 ++NumInputs;
291 break;
292 case InlineAsm::isClobber:
293 ++NumClobbers;
294 break;
295 case InlineAsm::isLabel:
296 if (NumClobbers)
297 return makeStringError("label constraint occurs after clobber "
298 "constraint");
299
300 ++NumLabels;
301 break;
302 }
303 }
304
305 switch (NumOutputs) {
306 case 0:
307 if (!Ty->getReturnType()->isVoidTy())
308 return makeStringError("inline asm without outputs must return void");
309 break;
310 case 1:
311 if (Ty->getReturnType()->isStructTy())
312 return makeStringError("inline asm with one output cannot return struct");
313 break;
314 default:
315 StructType *STy = dyn_cast<StructType>(Ty->getReturnType());
316 if (!STy || STy->getNumElements() != NumOutputs)
317 return makeStringError("number of output constraints does not match "
318 "number of return struct elements");
319 break;
320 }
321
322 if (Ty->getNumParams() != NumInputs)
323 return makeStringError("number of input constraints does not match number "
324 "of parameters");
325
326 // We don't have access to labels here, NumLabels will be checked separately.
327 return Error::success();
328 }
329