1 //===--- PPExpressions.cpp - Preprocessor Expression Evaluation -----------===//
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 Preprocessor::EvaluateDirectiveExpression method,
10 // which parses and evaluates integer constant expressions for #if directives.
11 //
12 //===----------------------------------------------------------------------===//
13 //
14 // FIXME: implement testing for #assert's.
15 //
16 //===----------------------------------------------------------------------===//
17
18 #include "clang/Basic/IdentifierTable.h"
19 #include "clang/Basic/SourceLocation.h"
20 #include "clang/Basic/SourceManager.h"
21 #include "clang/Basic/TargetInfo.h"
22 #include "clang/Basic/TokenKinds.h"
23 #include "clang/Lex/CodeCompletionHandler.h"
24 #include "clang/Lex/LexDiagnostic.h"
25 #include "clang/Lex/LiteralSupport.h"
26 #include "clang/Lex/MacroInfo.h"
27 #include "clang/Lex/PPCallbacks.h"
28 #include "clang/Lex/Preprocessor.h"
29 #include "clang/Lex/Token.h"
30 #include "llvm/ADT/APSInt.h"
31 #include "llvm/ADT/STLExtras.h"
32 #include "llvm/ADT/SmallString.h"
33 #include "llvm/ADT/StringExtras.h"
34 #include "llvm/ADT/StringRef.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/SaveAndRestore.h"
37 #include <cassert>
38
39 using namespace clang;
40
41 namespace {
42
43 /// PPValue - Represents the value of a subexpression of a preprocessor
44 /// conditional and the source range covered by it.
45 class PPValue {
46 SourceRange Range;
47 IdentifierInfo *II;
48
49 public:
50 llvm::APSInt Val;
51
52 // Default ctor - Construct an 'invalid' PPValue.
PPValue(unsigned BitWidth)53 PPValue(unsigned BitWidth) : Val(BitWidth) {}
54
55 // If this value was produced by directly evaluating an identifier, produce
56 // that identifier.
getIdentifier() const57 IdentifierInfo *getIdentifier() const { return II; }
setIdentifier(IdentifierInfo * II)58 void setIdentifier(IdentifierInfo *II) { this->II = II; }
59
getBitWidth() const60 unsigned getBitWidth() const { return Val.getBitWidth(); }
isUnsigned() const61 bool isUnsigned() const { return Val.isUnsigned(); }
62
getRange() const63 SourceRange getRange() const { return Range; }
64
setRange(SourceLocation L)65 void setRange(SourceLocation L) { Range.setBegin(L); Range.setEnd(L); }
setRange(SourceLocation B,SourceLocation E)66 void setRange(SourceLocation B, SourceLocation E) {
67 Range.setBegin(B); Range.setEnd(E);
68 }
setBegin(SourceLocation L)69 void setBegin(SourceLocation L) { Range.setBegin(L); }
setEnd(SourceLocation L)70 void setEnd(SourceLocation L) { Range.setEnd(L); }
71 };
72
73 } // end anonymous namespace
74
75 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
76 Token &PeekTok, bool ValueLive,
77 bool &IncludedUndefinedIds,
78 Preprocessor &PP);
79
80 /// DefinedTracker - This struct is used while parsing expressions to keep track
81 /// of whether !defined(X) has been seen.
82 ///
83 /// With this simple scheme, we handle the basic forms:
84 /// !defined(X) and !defined X
85 /// but we also trivially handle (silly) stuff like:
86 /// !!!defined(X) and +!defined(X) and !+!+!defined(X) and !(defined(X)).
87 struct DefinedTracker {
88 /// Each time a Value is evaluated, it returns information about whether the
89 /// parsed value is of the form defined(X), !defined(X) or is something else.
90 enum TrackerState {
91 DefinedMacro, // defined(X)
92 NotDefinedMacro, // !defined(X)
93 Unknown // Something else.
94 } State;
95 /// TheMacro - When the state is DefinedMacro or NotDefinedMacro, this
96 /// indicates the macro that was checked.
97 IdentifierInfo *TheMacro;
98 bool IncludedUndefinedIds = false;
99 };
100
101 /// EvaluateDefined - Process a 'defined(sym)' expression.
EvaluateDefined(PPValue & Result,Token & PeekTok,DefinedTracker & DT,bool ValueLive,Preprocessor & PP)102 static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
103 bool ValueLive, Preprocessor &PP) {
104 SourceLocation beginLoc(PeekTok.getLocation());
105 Result.setBegin(beginLoc);
106
107 // Get the next token, don't expand it.
108 PP.LexUnexpandedNonComment(PeekTok);
109
110 // Two options, it can either be a pp-identifier or a (.
111 SourceLocation LParenLoc;
112 if (PeekTok.is(tok::l_paren)) {
113 // Found a paren, remember we saw it and skip it.
114 LParenLoc = PeekTok.getLocation();
115 PP.LexUnexpandedNonComment(PeekTok);
116 }
117
118 if (PeekTok.is(tok::code_completion)) {
119 if (PP.getCodeCompletionHandler())
120 PP.getCodeCompletionHandler()->CodeCompleteMacroName(false);
121 PP.setCodeCompletionReached();
122 PP.LexUnexpandedNonComment(PeekTok);
123 }
124
125 // If we don't have a pp-identifier now, this is an error.
126 if (PP.CheckMacroName(PeekTok, MU_Other))
127 return true;
128
129 // Otherwise, we got an identifier, is it defined to something?
130 IdentifierInfo *II = PeekTok.getIdentifierInfo();
131 MacroDefinition Macro = PP.getMacroDefinition(II);
132 Result.Val = !!Macro;
133 Result.Val.setIsUnsigned(false); // Result is signed intmax_t.
134 DT.IncludedUndefinedIds = !Macro;
135
136 // If there is a macro, mark it used.
137 if (Result.Val != 0 && ValueLive)
138 PP.markMacroAsUsed(Macro.getMacroInfo());
139
140 // Save macro token for callback.
141 Token macroToken(PeekTok);
142
143 // If we are in parens, ensure we have a trailing ).
144 if (LParenLoc.isValid()) {
145 // Consume identifier.
146 Result.setEnd(PeekTok.getLocation());
147 PP.LexUnexpandedNonComment(PeekTok);
148
149 if (PeekTok.isNot(tok::r_paren)) {
150 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_after)
151 << "'defined'" << tok::r_paren;
152 PP.Diag(LParenLoc, diag::note_matching) << tok::l_paren;
153 return true;
154 }
155 // Consume the ).
156 PP.LexNonComment(PeekTok);
157 Result.setEnd(PeekTok.getLocation());
158 } else {
159 // Consume identifier.
160 Result.setEnd(PeekTok.getLocation());
161 PP.LexNonComment(PeekTok);
162 }
163
164 // [cpp.cond]p4:
165 // Prior to evaluation, macro invocations in the list of preprocessing
166 // tokens that will become the controlling constant expression are replaced
167 // (except for those macro names modified by the 'defined' unary operator),
168 // just as in normal text. If the token 'defined' is generated as a result
169 // of this replacement process or use of the 'defined' unary operator does
170 // not match one of the two specified forms prior to macro replacement, the
171 // behavior is undefined.
172 // This isn't an idle threat, consider this program:
173 // #define FOO
174 // #define BAR defined(FOO)
175 // #if BAR
176 // ...
177 // #else
178 // ...
179 // #endif
180 // clang and gcc will pick the #if branch while Visual Studio will take the
181 // #else branch. Emit a warning about this undefined behavior.
182 if (beginLoc.isMacroID()) {
183 bool IsFunctionTypeMacro =
184 PP.getSourceManager()
185 .getSLocEntry(PP.getSourceManager().getFileID(beginLoc))
186 .getExpansion()
187 .isFunctionMacroExpansion();
188 // For object-type macros, it's easy to replace
189 // #define FOO defined(BAR)
190 // with
191 // #if defined(BAR)
192 // #define FOO 1
193 // #else
194 // #define FOO 0
195 // #endif
196 // and doing so makes sense since compilers handle this differently in
197 // practice (see example further up). But for function-type macros,
198 // there is no good way to write
199 // # define FOO(x) (defined(M_ ## x) && M_ ## x)
200 // in a different way, and compilers seem to agree on how to behave here.
201 // So warn by default on object-type macros, but only warn in -pedantic
202 // mode on function-type macros.
203 if (IsFunctionTypeMacro)
204 PP.Diag(beginLoc, diag::warn_defined_in_function_type_macro);
205 else
206 PP.Diag(beginLoc, diag::warn_defined_in_object_type_macro);
207 }
208
209 // Invoke the 'defined' callback.
210 if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
211 Callbacks->Defined(macroToken, Macro,
212 SourceRange(beginLoc, PeekTok.getLocation()));
213 }
214
215 // Success, remember that we saw defined(X).
216 DT.State = DefinedTracker::DefinedMacro;
217 DT.TheMacro = II;
218 return false;
219 }
220
221 /// EvaluateValue - Evaluate the token PeekTok (and any others needed) and
222 /// return the computed value in Result. Return true if there was an error
223 /// parsing. This function also returns information about the form of the
224 /// expression in DT. See above for information on what DT means.
225 ///
226 /// If ValueLive is false, then this value is being evaluated in a context where
227 /// the result is not used. As such, avoid diagnostics that relate to
228 /// evaluation.
EvaluateValue(PPValue & Result,Token & PeekTok,DefinedTracker & DT,bool ValueLive,Preprocessor & PP)229 static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
230 bool ValueLive, Preprocessor &PP) {
231 DT.State = DefinedTracker::Unknown;
232
233 Result.setIdentifier(nullptr);
234
235 if (PeekTok.is(tok::code_completion)) {
236 if (PP.getCodeCompletionHandler())
237 PP.getCodeCompletionHandler()->CodeCompletePreprocessorExpression();
238 PP.setCodeCompletionReached();
239 PP.LexNonComment(PeekTok);
240 }
241
242 switch (PeekTok.getKind()) {
243 default:
244 // If this token's spelling is a pp-identifier, check to see if it is
245 // 'defined' or if it is a macro. Note that we check here because many
246 // keywords are pp-identifiers, so we can't check the kind.
247 if (IdentifierInfo *II = PeekTok.getIdentifierInfo()) {
248 // Handle "defined X" and "defined(X)".
249 if (II->isStr("defined"))
250 return EvaluateDefined(Result, PeekTok, DT, ValueLive, PP);
251
252 if (!II->isCPlusPlusOperatorKeyword()) {
253 // If this identifier isn't 'defined' or one of the special
254 // preprocessor keywords and it wasn't macro expanded, it turns
255 // into a simple 0
256 if (ValueLive) {
257 PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II;
258
259 const DiagnosticsEngine &DiagEngine = PP.getDiagnostics();
260 // If 'Wundef' is enabled, do not emit 'undef-prefix' diagnostics.
261 if (DiagEngine.isIgnored(diag::warn_pp_undef_identifier,
262 PeekTok.getLocation())) {
263 const std::vector<std::string> UndefPrefixes =
264 DiagEngine.getDiagnosticOptions().UndefPrefixes;
265 const StringRef IdentifierName = II->getName();
266 if (llvm::any_of(UndefPrefixes,
267 [&IdentifierName](const std::string &Prefix) {
268 return IdentifierName.startswith(Prefix);
269 }))
270 PP.Diag(PeekTok, diag::warn_pp_undef_prefix)
271 << AddFlagValue{llvm::join(UndefPrefixes, ",")} << II;
272 }
273 }
274 Result.Val = 0;
275 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0.
276 Result.setIdentifier(II);
277 Result.setRange(PeekTok.getLocation());
278 DT.IncludedUndefinedIds = true;
279 PP.LexNonComment(PeekTok);
280 return false;
281 }
282 }
283 PP.Diag(PeekTok, diag::err_pp_expr_bad_token_start_expr);
284 return true;
285 case tok::eod:
286 case tok::r_paren:
287 // If there is no expression, report and exit.
288 PP.Diag(PeekTok, diag::err_pp_expected_value_in_expr);
289 return true;
290 case tok::numeric_constant: {
291 SmallString<64> IntegerBuffer;
292 bool NumberInvalid = false;
293 StringRef Spelling = PP.getSpelling(PeekTok, IntegerBuffer,
294 &NumberInvalid);
295 if (NumberInvalid)
296 return true; // a diagnostic was already reported
297
298 NumericLiteralParser Literal(Spelling, PeekTok.getLocation(),
299 PP.getSourceManager(), PP.getLangOpts(),
300 PP.getTargetInfo(), PP.getDiagnostics());
301 if (Literal.hadError)
302 return true; // a diagnostic was already reported.
303
304 if (Literal.isFloatingLiteral() || Literal.isImaginary) {
305 PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
306 return true;
307 }
308 assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
309
310 // Complain about, and drop, any ud-suffix.
311 if (Literal.hasUDSuffix())
312 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*integer*/1;
313
314 // 'long long' is a C99 or C++11 feature.
315 if (!PP.getLangOpts().C99 && Literal.isLongLong) {
316 if (PP.getLangOpts().CPlusPlus)
317 PP.Diag(PeekTok,
318 PP.getLangOpts().CPlusPlus11 ?
319 diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
320 else
321 PP.Diag(PeekTok, diag::ext_c99_longlong);
322 }
323
324 // 'z/uz' literals are a C++2b feature.
325 if (Literal.isSizeT)
326 PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus
327 ? PP.getLangOpts().CPlusPlus2b
328 ? diag::warn_cxx20_compat_size_t_suffix
329 : diag::ext_cxx2b_size_t_suffix
330 : diag::err_cxx2b_size_t_suffix);
331
332 // Parse the integer literal into Result.
333 if (Literal.GetIntegerValue(Result.Val)) {
334 // Overflow parsing integer literal.
335 if (ValueLive)
336 PP.Diag(PeekTok, diag::err_integer_literal_too_large)
337 << /* Unsigned */ 1;
338 Result.Val.setIsUnsigned(true);
339 } else {
340 // Set the signedness of the result to match whether there was a U suffix
341 // or not.
342 Result.Val.setIsUnsigned(Literal.isUnsigned);
343
344 // Detect overflow based on whether the value is signed. If signed
345 // and if the value is too large, emit a warning "integer constant is so
346 // large that it is unsigned" e.g. on 12345678901234567890 where intmax_t
347 // is 64-bits.
348 if (!Literal.isUnsigned && Result.Val.isNegative()) {
349 // Octal, hexadecimal, and binary literals are implicitly unsigned if
350 // the value does not fit into a signed integer type.
351 if (ValueLive && Literal.getRadix() == 10)
352 PP.Diag(PeekTok, diag::ext_integer_literal_too_large_for_signed);
353 Result.Val.setIsUnsigned(true);
354 }
355 }
356
357 // Consume the token.
358 Result.setRange(PeekTok.getLocation());
359 PP.LexNonComment(PeekTok);
360 return false;
361 }
362 case tok::char_constant: // 'x'
363 case tok::wide_char_constant: // L'x'
364 case tok::utf8_char_constant: // u8'x'
365 case tok::utf16_char_constant: // u'x'
366 case tok::utf32_char_constant: { // U'x'
367 // Complain about, and drop, any ud-suffix.
368 if (PeekTok.hasUDSuffix())
369 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*character*/0;
370
371 SmallString<32> CharBuffer;
372 bool CharInvalid = false;
373 StringRef ThisTok = PP.getSpelling(PeekTok, CharBuffer, &CharInvalid);
374 if (CharInvalid)
375 return true;
376
377 CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(),
378 PeekTok.getLocation(), PP, PeekTok.getKind());
379 if (Literal.hadError())
380 return true; // A diagnostic was already emitted.
381
382 // Character literals are always int or wchar_t, expand to intmax_t.
383 const TargetInfo &TI = PP.getTargetInfo();
384 unsigned NumBits;
385 if (Literal.isMultiChar())
386 NumBits = TI.getIntWidth();
387 else if (Literal.isWide())
388 NumBits = TI.getWCharWidth();
389 else if (Literal.isUTF16())
390 NumBits = TI.getChar16Width();
391 else if (Literal.isUTF32())
392 NumBits = TI.getChar32Width();
393 else // char or char8_t
394 NumBits = TI.getCharWidth();
395
396 // Set the width.
397 llvm::APSInt Val(NumBits);
398 // Set the value.
399 Val = Literal.getValue();
400 // Set the signedness. UTF-16 and UTF-32 are always unsigned
401 if (Literal.isWide())
402 Val.setIsUnsigned(!TargetInfo::isTypeSigned(TI.getWCharType()));
403 else if (!Literal.isUTF16() && !Literal.isUTF32())
404 Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned);
405
406 if (Result.Val.getBitWidth() > Val.getBitWidth()) {
407 Result.Val = Val.extend(Result.Val.getBitWidth());
408 } else {
409 assert(Result.Val.getBitWidth() == Val.getBitWidth() &&
410 "intmax_t smaller than char/wchar_t?");
411 Result.Val = Val;
412 }
413
414 // Consume the token.
415 Result.setRange(PeekTok.getLocation());
416 PP.LexNonComment(PeekTok);
417 return false;
418 }
419 case tok::l_paren: {
420 SourceLocation Start = PeekTok.getLocation();
421 PP.LexNonComment(PeekTok); // Eat the (.
422 // Parse the value and if there are any binary operators involved, parse
423 // them.
424 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
425
426 // If this is a silly value like (X), which doesn't need parens, check for
427 // !(defined X).
428 if (PeekTok.is(tok::r_paren)) {
429 // Just use DT unmodified as our result.
430 } else {
431 // Otherwise, we have something like (x+y), and we consumed '(x'.
432 if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive,
433 DT.IncludedUndefinedIds, PP))
434 return true;
435
436 if (PeekTok.isNot(tok::r_paren)) {
437 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_rparen)
438 << Result.getRange();
439 PP.Diag(Start, diag::note_matching) << tok::l_paren;
440 return true;
441 }
442 DT.State = DefinedTracker::Unknown;
443 }
444 Result.setRange(Start, PeekTok.getLocation());
445 Result.setIdentifier(nullptr);
446 PP.LexNonComment(PeekTok); // Eat the ).
447 return false;
448 }
449 case tok::plus: {
450 SourceLocation Start = PeekTok.getLocation();
451 // Unary plus doesn't modify the value.
452 PP.LexNonComment(PeekTok);
453 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
454 Result.setBegin(Start);
455 Result.setIdentifier(nullptr);
456 return false;
457 }
458 case tok::minus: {
459 SourceLocation Loc = PeekTok.getLocation();
460 PP.LexNonComment(PeekTok);
461 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
462 Result.setBegin(Loc);
463 Result.setIdentifier(nullptr);
464
465 // C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
466 Result.Val = -Result.Val;
467
468 // -MININT is the only thing that overflows. Unsigned never overflows.
469 bool Overflow = !Result.isUnsigned() && Result.Val.isMinSignedValue();
470
471 // If this operator is live and overflowed, report the issue.
472 if (Overflow && ValueLive)
473 PP.Diag(Loc, diag::warn_pp_expr_overflow) << Result.getRange();
474
475 DT.State = DefinedTracker::Unknown;
476 return false;
477 }
478
479 case tok::tilde: {
480 SourceLocation Start = PeekTok.getLocation();
481 PP.LexNonComment(PeekTok);
482 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
483 Result.setBegin(Start);
484 Result.setIdentifier(nullptr);
485
486 // C99 6.5.3.3p4: The sign of the result matches the sign of the operand.
487 Result.Val = ~Result.Val;
488 DT.State = DefinedTracker::Unknown;
489 return false;
490 }
491
492 case tok::exclaim: {
493 SourceLocation Start = PeekTok.getLocation();
494 PP.LexNonComment(PeekTok);
495 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
496 Result.setBegin(Start);
497 Result.Val = !Result.Val;
498 // C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed.
499 Result.Val.setIsUnsigned(false);
500 Result.setIdentifier(nullptr);
501
502 if (DT.State == DefinedTracker::DefinedMacro)
503 DT.State = DefinedTracker::NotDefinedMacro;
504 else if (DT.State == DefinedTracker::NotDefinedMacro)
505 DT.State = DefinedTracker::DefinedMacro;
506 return false;
507 }
508 case tok::kw_true:
509 case tok::kw_false:
510 Result.Val = PeekTok.getKind() == tok::kw_true;
511 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0.
512 Result.setIdentifier(PeekTok.getIdentifierInfo());
513 Result.setRange(PeekTok.getLocation());
514 PP.LexNonComment(PeekTok);
515 return false;
516
517 // FIXME: Handle #assert
518 }
519 }
520
521 /// getPrecedence - Return the precedence of the specified binary operator
522 /// token. This returns:
523 /// ~0 - Invalid token.
524 /// 14 -> 3 - various operators.
525 /// 0 - 'eod' or ')'
getPrecedence(tok::TokenKind Kind)526 static unsigned getPrecedence(tok::TokenKind Kind) {
527 switch (Kind) {
528 default: return ~0U;
529 case tok::percent:
530 case tok::slash:
531 case tok::star: return 14;
532 case tok::plus:
533 case tok::minus: return 13;
534 case tok::lessless:
535 case tok::greatergreater: return 12;
536 case tok::lessequal:
537 case tok::less:
538 case tok::greaterequal:
539 case tok::greater: return 11;
540 case tok::exclaimequal:
541 case tok::equalequal: return 10;
542 case tok::amp: return 9;
543 case tok::caret: return 8;
544 case tok::pipe: return 7;
545 case tok::ampamp: return 6;
546 case tok::pipepipe: return 5;
547 case tok::question: return 4;
548 case tok::comma: return 3;
549 case tok::colon: return 2;
550 case tok::r_paren: return 0;// Lowest priority, end of expr.
551 case tok::eod: return 0;// Lowest priority, end of directive.
552 }
553 }
554
diagnoseUnexpectedOperator(Preprocessor & PP,PPValue & LHS,Token & Tok)555 static void diagnoseUnexpectedOperator(Preprocessor &PP, PPValue &LHS,
556 Token &Tok) {
557 if (Tok.is(tok::l_paren) && LHS.getIdentifier())
558 PP.Diag(LHS.getRange().getBegin(), diag::err_pp_expr_bad_token_lparen)
559 << LHS.getIdentifier();
560 else
561 PP.Diag(Tok.getLocation(), diag::err_pp_expr_bad_token_binop)
562 << LHS.getRange();
563 }
564
565 /// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is
566 /// PeekTok, and whose precedence is PeekPrec. This returns the result in LHS.
567 ///
568 /// If ValueLive is false, then this value is being evaluated in a context where
569 /// the result is not used. As such, avoid diagnostics that relate to
570 /// evaluation, such as division by zero warnings.
EvaluateDirectiveSubExpr(PPValue & LHS,unsigned MinPrec,Token & PeekTok,bool ValueLive,bool & IncludedUndefinedIds,Preprocessor & PP)571 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
572 Token &PeekTok, bool ValueLive,
573 bool &IncludedUndefinedIds,
574 Preprocessor &PP) {
575 unsigned PeekPrec = getPrecedence(PeekTok.getKind());
576 // If this token isn't valid, report the error.
577 if (PeekPrec == ~0U) {
578 diagnoseUnexpectedOperator(PP, LHS, PeekTok);
579 return true;
580 }
581
582 while (true) {
583 // If this token has a lower precedence than we are allowed to parse, return
584 // it so that higher levels of the recursion can parse it.
585 if (PeekPrec < MinPrec)
586 return false;
587
588 tok::TokenKind Operator = PeekTok.getKind();
589
590 // If this is a short-circuiting operator, see if the RHS of the operator is
591 // dead. Note that this cannot just clobber ValueLive. Consider
592 // "0 && 1 ? 4 : 1 / 0", which is parsed as "(0 && 1) ? 4 : (1 / 0)". In
593 // this example, the RHS of the && being dead does not make the rest of the
594 // expr dead.
595 bool RHSIsLive;
596 if (Operator == tok::ampamp && LHS.Val == 0)
597 RHSIsLive = false; // RHS of "0 && x" is dead.
598 else if (Operator == tok::pipepipe && LHS.Val != 0)
599 RHSIsLive = false; // RHS of "1 || x" is dead.
600 else if (Operator == tok::question && LHS.Val == 0)
601 RHSIsLive = false; // RHS (x) of "0 ? x : y" is dead.
602 else
603 RHSIsLive = ValueLive;
604
605 // Consume the operator, remembering the operator's location for reporting.
606 SourceLocation OpLoc = PeekTok.getLocation();
607 PP.LexNonComment(PeekTok);
608
609 PPValue RHS(LHS.getBitWidth());
610 // Parse the RHS of the operator.
611 DefinedTracker DT;
612 if (EvaluateValue(RHS, PeekTok, DT, RHSIsLive, PP)) return true;
613 IncludedUndefinedIds = DT.IncludedUndefinedIds;
614
615 // Remember the precedence of this operator and get the precedence of the
616 // operator immediately to the right of the RHS.
617 unsigned ThisPrec = PeekPrec;
618 PeekPrec = getPrecedence(PeekTok.getKind());
619
620 // If this token isn't valid, report the error.
621 if (PeekPrec == ~0U) {
622 diagnoseUnexpectedOperator(PP, RHS, PeekTok);
623 return true;
624 }
625
626 // Decide whether to include the next binop in this subexpression. For
627 // example, when parsing x+y*z and looking at '*', we want to recursively
628 // handle y*z as a single subexpression. We do this because the precedence
629 // of * is higher than that of +. The only strange case we have to handle
630 // here is for the ?: operator, where the precedence is actually lower than
631 // the LHS of the '?'. The grammar rule is:
632 //
633 // conditional-expression ::=
634 // logical-OR-expression ? expression : conditional-expression
635 // where 'expression' is actually comma-expression.
636 unsigned RHSPrec;
637 if (Operator == tok::question)
638 // The RHS of "?" should be maximally consumed as an expression.
639 RHSPrec = getPrecedence(tok::comma);
640 else // All others should munch while higher precedence.
641 RHSPrec = ThisPrec+1;
642
643 if (PeekPrec >= RHSPrec) {
644 if (EvaluateDirectiveSubExpr(RHS, RHSPrec, PeekTok, RHSIsLive,
645 IncludedUndefinedIds, PP))
646 return true;
647 PeekPrec = getPrecedence(PeekTok.getKind());
648 }
649 assert(PeekPrec <= ThisPrec && "Recursion didn't work!");
650
651 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
652 // either operand is unsigned.
653 llvm::APSInt Res(LHS.getBitWidth());
654 switch (Operator) {
655 case tok::question: // No UAC for x and y in "x ? y : z".
656 case tok::lessless: // Shift amount doesn't UAC with shift value.
657 case tok::greatergreater: // Shift amount doesn't UAC with shift value.
658 case tok::comma: // Comma operands are not subject to UACs.
659 case tok::pipepipe: // Logical || does not do UACs.
660 case tok::ampamp: // Logical && does not do UACs.
661 break; // No UAC
662 default:
663 Res.setIsUnsigned(LHS.isUnsigned()|RHS.isUnsigned());
664 // If this just promoted something from signed to unsigned, and if the
665 // value was negative, warn about it.
666 if (ValueLive && Res.isUnsigned()) {
667 if (!LHS.isUnsigned() && LHS.Val.isNegative())
668 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 0
669 << toString(LHS.Val, 10, true) + " to " +
670 toString(LHS.Val, 10, false)
671 << LHS.getRange() << RHS.getRange();
672 if (!RHS.isUnsigned() && RHS.Val.isNegative())
673 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 1
674 << toString(RHS.Val, 10, true) + " to " +
675 toString(RHS.Val, 10, false)
676 << LHS.getRange() << RHS.getRange();
677 }
678 LHS.Val.setIsUnsigned(Res.isUnsigned());
679 RHS.Val.setIsUnsigned(Res.isUnsigned());
680 }
681
682 bool Overflow = false;
683 switch (Operator) {
684 default: llvm_unreachable("Unknown operator token!");
685 case tok::percent:
686 if (RHS.Val != 0)
687 Res = LHS.Val % RHS.Val;
688 else if (ValueLive) {
689 PP.Diag(OpLoc, diag::err_pp_remainder_by_zero)
690 << LHS.getRange() << RHS.getRange();
691 return true;
692 }
693 break;
694 case tok::slash:
695 if (RHS.Val != 0) {
696 if (LHS.Val.isSigned())
697 Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS.Val, Overflow), false);
698 else
699 Res = LHS.Val / RHS.Val;
700 } else if (ValueLive) {
701 PP.Diag(OpLoc, diag::err_pp_division_by_zero)
702 << LHS.getRange() << RHS.getRange();
703 return true;
704 }
705 break;
706
707 case tok::star:
708 if (Res.isSigned())
709 Res = llvm::APSInt(LHS.Val.smul_ov(RHS.Val, Overflow), false);
710 else
711 Res = LHS.Val * RHS.Val;
712 break;
713 case tok::lessless: {
714 // Determine whether overflow is about to happen.
715 if (LHS.isUnsigned())
716 Res = LHS.Val.ushl_ov(RHS.Val, Overflow);
717 else
718 Res = llvm::APSInt(LHS.Val.sshl_ov(RHS.Val, Overflow), false);
719 break;
720 }
721 case tok::greatergreater: {
722 // Determine whether overflow is about to happen.
723 unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
724 if (ShAmt >= LHS.getBitWidth()) {
725 Overflow = true;
726 ShAmt = LHS.getBitWidth()-1;
727 }
728 Res = LHS.Val >> ShAmt;
729 break;
730 }
731 case tok::plus:
732 if (LHS.isUnsigned())
733 Res = LHS.Val + RHS.Val;
734 else
735 Res = llvm::APSInt(LHS.Val.sadd_ov(RHS.Val, Overflow), false);
736 break;
737 case tok::minus:
738 if (LHS.isUnsigned())
739 Res = LHS.Val - RHS.Val;
740 else
741 Res = llvm::APSInt(LHS.Val.ssub_ov(RHS.Val, Overflow), false);
742 break;
743 case tok::lessequal:
744 Res = LHS.Val <= RHS.Val;
745 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
746 break;
747 case tok::less:
748 Res = LHS.Val < RHS.Val;
749 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
750 break;
751 case tok::greaterequal:
752 Res = LHS.Val >= RHS.Val;
753 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
754 break;
755 case tok::greater:
756 Res = LHS.Val > RHS.Val;
757 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
758 break;
759 case tok::exclaimequal:
760 Res = LHS.Val != RHS.Val;
761 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
762 break;
763 case tok::equalequal:
764 Res = LHS.Val == RHS.Val;
765 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
766 break;
767 case tok::amp:
768 Res = LHS.Val & RHS.Val;
769 break;
770 case tok::caret:
771 Res = LHS.Val ^ RHS.Val;
772 break;
773 case tok::pipe:
774 Res = LHS.Val | RHS.Val;
775 break;
776 case tok::ampamp:
777 Res = (LHS.Val != 0 && RHS.Val != 0);
778 Res.setIsUnsigned(false); // C99 6.5.13p3, result is always int (signed)
779 break;
780 case tok::pipepipe:
781 Res = (LHS.Val != 0 || RHS.Val != 0);
782 Res.setIsUnsigned(false); // C99 6.5.14p3, result is always int (signed)
783 break;
784 case tok::comma:
785 // Comma is invalid in pp expressions in c89/c++ mode, but is valid in C99
786 // if not being evaluated.
787 if (!PP.getLangOpts().C99 || ValueLive)
788 PP.Diag(OpLoc, diag::ext_pp_comma_expr)
789 << LHS.getRange() << RHS.getRange();
790 Res = RHS.Val; // LHS = LHS,RHS -> RHS.
791 break;
792 case tok::question: {
793 // Parse the : part of the expression.
794 if (PeekTok.isNot(tok::colon)) {
795 PP.Diag(PeekTok.getLocation(), diag::err_expected)
796 << tok::colon << LHS.getRange() << RHS.getRange();
797 PP.Diag(OpLoc, diag::note_matching) << tok::question;
798 return true;
799 }
800 // Consume the :.
801 PP.LexNonComment(PeekTok);
802
803 // Evaluate the value after the :.
804 bool AfterColonLive = ValueLive && LHS.Val == 0;
805 PPValue AfterColonVal(LHS.getBitWidth());
806 DefinedTracker DT;
807 if (EvaluateValue(AfterColonVal, PeekTok, DT, AfterColonLive, PP))
808 return true;
809
810 // Parse anything after the : with the same precedence as ?. We allow
811 // things of equal precedence because ?: is right associative.
812 if (EvaluateDirectiveSubExpr(AfterColonVal, ThisPrec,
813 PeekTok, AfterColonLive,
814 IncludedUndefinedIds, PP))
815 return true;
816
817 // Now that we have the condition, the LHS and the RHS of the :, evaluate.
818 Res = LHS.Val != 0 ? RHS.Val : AfterColonVal.Val;
819 RHS.setEnd(AfterColonVal.getRange().getEnd());
820
821 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
822 // either operand is unsigned.
823 Res.setIsUnsigned(RHS.isUnsigned() | AfterColonVal.isUnsigned());
824
825 // Figure out the precedence of the token after the : part.
826 PeekPrec = getPrecedence(PeekTok.getKind());
827 break;
828 }
829 case tok::colon:
830 // Don't allow :'s to float around without being part of ?: exprs.
831 PP.Diag(OpLoc, diag::err_pp_colon_without_question)
832 << LHS.getRange() << RHS.getRange();
833 return true;
834 }
835
836 // If this operator is live and overflowed, report the issue.
837 if (Overflow && ValueLive)
838 PP.Diag(OpLoc, diag::warn_pp_expr_overflow)
839 << LHS.getRange() << RHS.getRange();
840
841 // Put the result back into 'LHS' for our next iteration.
842 LHS.Val = Res;
843 LHS.setEnd(RHS.getRange().getEnd());
844 RHS.setIdentifier(nullptr);
845 }
846 }
847
848 /// EvaluateDirectiveExpression - Evaluate an integer constant expression that
849 /// may occur after a #if or #elif directive. If the expression is equivalent
850 /// to "!defined(X)" return X in IfNDefMacro.
851 Preprocessor::DirectiveEvalResult
EvaluateDirectiveExpression(IdentifierInfo * & IfNDefMacro)852 Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro) {
853 SaveAndRestore<bool> PPDir(ParsingIfOrElifDirective, true);
854 // Save the current state of 'DisableMacroExpansion' and reset it to false. If
855 // 'DisableMacroExpansion' is true, then we must be in a macro argument list
856 // in which case a directive is undefined behavior. We want macros to be able
857 // to recursively expand in order to get more gcc-list behavior, so we force
858 // DisableMacroExpansion to false and restore it when we're done parsing the
859 // expression.
860 bool DisableMacroExpansionAtStartOfDirective = DisableMacroExpansion;
861 DisableMacroExpansion = false;
862
863 // Peek ahead one token.
864 Token Tok;
865 LexNonComment(Tok);
866
867 // C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
868 unsigned BitWidth = getTargetInfo().getIntMaxTWidth();
869
870 PPValue ResVal(BitWidth);
871 DefinedTracker DT;
872 SourceLocation ExprStartLoc = SourceMgr.getExpansionLoc(Tok.getLocation());
873 if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
874 // Parse error, skip the rest of the macro line.
875 SourceRange ConditionRange = ExprStartLoc;
876 if (Tok.isNot(tok::eod))
877 ConditionRange = DiscardUntilEndOfDirective();
878
879 // Restore 'DisableMacroExpansion'.
880 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
881
882 // We cannot trust the source range from the value because there was a
883 // parse error. Track the range manually -- the end of the directive is the
884 // end of the condition range.
885 return {false,
886 DT.IncludedUndefinedIds,
887 {ExprStartLoc, ConditionRange.getEnd()}};
888 }
889
890 // If we are at the end of the expression after just parsing a value, there
891 // must be no (unparenthesized) binary operators involved, so we can exit
892 // directly.
893 if (Tok.is(tok::eod)) {
894 // If the expression we parsed was of the form !defined(macro), return the
895 // macro in IfNDefMacro.
896 if (DT.State == DefinedTracker::NotDefinedMacro)
897 IfNDefMacro = DT.TheMacro;
898
899 // Restore 'DisableMacroExpansion'.
900 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
901 return {ResVal.Val != 0, DT.IncludedUndefinedIds, ResVal.getRange()};
902 }
903
904 // Otherwise, we must have a binary operator (e.g. "#if 1 < 2"), so parse the
905 // operator and the stuff after it.
906 if (EvaluateDirectiveSubExpr(ResVal, getPrecedence(tok::question),
907 Tok, true, DT.IncludedUndefinedIds, *this)) {
908 // Parse error, skip the rest of the macro line.
909 if (Tok.isNot(tok::eod))
910 DiscardUntilEndOfDirective();
911
912 // Restore 'DisableMacroExpansion'.
913 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
914 return {false, DT.IncludedUndefinedIds, ResVal.getRange()};
915 }
916
917 // If we aren't at the tok::eod token, something bad happened, like an extra
918 // ')' token.
919 if (Tok.isNot(tok::eod)) {
920 Diag(Tok, diag::err_pp_expected_eol);
921 DiscardUntilEndOfDirective();
922 }
923
924 // Restore 'DisableMacroExpansion'.
925 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
926 return {ResVal.Val != 0, DT.IncludedUndefinedIds, ResVal.getRange()};
927 }
928