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
39using namespace clang;
40
41namespace {
42
43/// PPValue - Represents the value of a subexpression of a preprocessor
44/// conditional and the source range covered by it.
45class PPValue {
46 SourceRange Range;
47 IdentifierInfo *II = nullptr;
48
49public:
50 llvm::APSInt Val;
51
52 // Default ctor - Construct an 'invalid' PPValue.
53 PPValue(unsigned BitWidth) : Val(BitWidth) {}
54
55 // If this value was produced by directly evaluating an identifier, produce
56 // that identifier.
57 IdentifierInfo *getIdentifier() const { return II; }
58 void setIdentifier(IdentifierInfo *II) { this->II = II; }
59
60 unsigned getBitWidth() const { return Val.getBitWidth(); }
61 bool isUnsigned() const { return Val.isUnsigned(); }
62
63 SourceRange getRange() const { return Range; }
64
65 void setRange(SourceLocation L) { Range.setBegin(L); Range.setEnd(L); }
66 void setRange(SourceLocation B, SourceLocation E) {
67 Range.setBegin(B); Range.setEnd(E);
68 }
69 void setBegin(SourceLocation L) { Range.setBegin(L); }
70 void setEnd(SourceLocation L) { Range.setEnd(L); }
71};
72
73} // end anonymous namespace
74
75static 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)).
87struct 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.
102static 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(Result&: PeekTok);
109
110 // Two options, it can either be a pp-identifier or a (.
111 SourceLocation LParenLoc;
112 if (PeekTok.is(K: tok::l_paren)) {
113 // Found a paren, remember we saw it and skip it.
114 LParenLoc = PeekTok.getLocation();
115 PP.LexUnexpandedNonComment(Result&: PeekTok);
116 }
117
118 if (PeekTok.is(K: tok::code_completion)) {
119 if (PP.getCodeCompletionHandler())
120 PP.getCodeCompletionHandler()->CodeCompleteMacroName(IsDefinition: false);
121 PP.setCodeCompletionReached();
122 PP.LexUnexpandedNonComment(Result&: PeekTok);
123 }
124
125 // If we don't have a pp-identifier now, this is an error.
126 if (PP.CheckMacroName(MacroNameTok&: PeekTok, isDefineUndef: 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 PP.emitMacroExpansionWarnings(
137 Identifier: PeekTok,
138 IsIfnDef: (II->getName() == "INFINITY" || II->getName() == "NAN") ? true : false);
139
140 // If there is a macro, mark it used.
141 if (Result.Val != 0 && ValueLive)
142 PP.markMacroAsUsed(MI: Macro.getMacroInfo());
143
144 // Save macro token for callback.
145 Token macroToken(PeekTok);
146
147 // If we are in parens, ensure we have a trailing ).
148 if (LParenLoc.isValid()) {
149 // Consume identifier.
150 Result.setEnd(PeekTok.getLocation());
151 PP.LexUnexpandedNonComment(Result&: PeekTok);
152
153 if (PeekTok.isNot(K: tok::r_paren)) {
154 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_after)
155 << "'defined'" << tok::r_paren;
156 PP.Diag(LParenLoc, diag::note_matching) << tok::l_paren;
157 return true;
158 }
159 // Consume the ).
160 PP.LexNonComment(Result&: PeekTok);
161 Result.setEnd(PeekTok.getLocation());
162 } else {
163 // Consume identifier.
164 Result.setEnd(PeekTok.getLocation());
165 PP.LexNonComment(Result&: PeekTok);
166 }
167
168 // [cpp.cond]p4:
169 // Prior to evaluation, macro invocations in the list of preprocessing
170 // tokens that will become the controlling constant expression are replaced
171 // (except for those macro names modified by the 'defined' unary operator),
172 // just as in normal text. If the token 'defined' is generated as a result
173 // of this replacement process or use of the 'defined' unary operator does
174 // not match one of the two specified forms prior to macro replacement, the
175 // behavior is undefined.
176 // This isn't an idle threat, consider this program:
177 // #define FOO
178 // #define BAR defined(FOO)
179 // #if BAR
180 // ...
181 // #else
182 // ...
183 // #endif
184 // clang and gcc will pick the #if branch while Visual Studio will take the
185 // #else branch. Emit a warning about this undefined behavior.
186 if (beginLoc.isMacroID()) {
187 bool IsFunctionTypeMacro =
188 PP.getSourceManager()
189 .getSLocEntry(FID: PP.getSourceManager().getFileID(SpellingLoc: beginLoc))
190 .getExpansion()
191 .isFunctionMacroExpansion();
192 // For object-type macros, it's easy to replace
193 // #define FOO defined(BAR)
194 // with
195 // #if defined(BAR)
196 // #define FOO 1
197 // #else
198 // #define FOO 0
199 // #endif
200 // and doing so makes sense since compilers handle this differently in
201 // practice (see example further up). But for function-type macros,
202 // there is no good way to write
203 // # define FOO(x) (defined(M_ ## x) && M_ ## x)
204 // in a different way, and compilers seem to agree on how to behave here.
205 // So warn by default on object-type macros, but only warn in -pedantic
206 // mode on function-type macros.
207 if (IsFunctionTypeMacro)
208 PP.Diag(beginLoc, diag::warn_defined_in_function_type_macro);
209 else
210 PP.Diag(beginLoc, diag::warn_defined_in_object_type_macro);
211 }
212
213 // Invoke the 'defined' callback.
214 if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
215 Callbacks->Defined(MacroNameTok: macroToken, MD: Macro,
216 Range: SourceRange(beginLoc, PeekTok.getLocation()));
217 }
218
219 // Success, remember that we saw defined(X).
220 DT.State = DefinedTracker::DefinedMacro;
221 DT.TheMacro = II;
222 return false;
223}
224
225/// EvaluateValue - Evaluate the token PeekTok (and any others needed) and
226/// return the computed value in Result. Return true if there was an error
227/// parsing. This function also returns information about the form of the
228/// expression in DT. See above for information on what DT means.
229///
230/// If ValueLive is false, then this value is being evaluated in a context where
231/// the result is not used. As such, avoid diagnostics that relate to
232/// evaluation.
233static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
234 bool ValueLive, Preprocessor &PP) {
235 DT.State = DefinedTracker::Unknown;
236
237 Result.setIdentifier(nullptr);
238
239 if (PeekTok.is(K: tok::code_completion)) {
240 if (PP.getCodeCompletionHandler())
241 PP.getCodeCompletionHandler()->CodeCompletePreprocessorExpression();
242 PP.setCodeCompletionReached();
243 PP.LexNonComment(Result&: PeekTok);
244 }
245
246 switch (PeekTok.getKind()) {
247 default:
248 // If this token's spelling is a pp-identifier, check to see if it is
249 // 'defined' or if it is a macro. Note that we check here because many
250 // keywords are pp-identifiers, so we can't check the kind.
251 if (IdentifierInfo *II = PeekTok.getIdentifierInfo()) {
252 // Handle "defined X" and "defined(X)".
253 if (II->isStr(Str: "defined"))
254 return EvaluateDefined(Result, PeekTok, DT, ValueLive, PP);
255
256 if (!II->isCPlusPlusOperatorKeyword()) {
257 // If this identifier isn't 'defined' or one of the special
258 // preprocessor keywords and it wasn't macro expanded, it turns
259 // into a simple 0
260 if (ValueLive) {
261 PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II;
262
263 const DiagnosticsEngine &DiagEngine = PP.getDiagnostics();
264 // If 'Wundef' is enabled, do not emit 'undef-prefix' diagnostics.
265 if (DiagEngine.isIgnored(diag::DiagID: warn_pp_undef_identifier,
266 Loc: PeekTok.getLocation())) {
267 const std::vector<std::string> UndefPrefixes =
268 DiagEngine.getDiagnosticOptions().UndefPrefixes;
269 const StringRef IdentifierName = II->getName();
270 if (llvm::any_of(Range: UndefPrefixes,
271 P: [&IdentifierName](const std::string &Prefix) {
272 return IdentifierName.starts_with(Prefix);
273 }))
274 PP.Diag(PeekTok, diag::warn_pp_undef_prefix)
275 << AddFlagValue{llvm::join(R: UndefPrefixes, Separator: ",")} << II;
276 }
277 }
278 Result.Val = 0;
279 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0.
280 Result.setIdentifier(II);
281 Result.setRange(PeekTok.getLocation());
282 DT.IncludedUndefinedIds = true;
283 PP.LexNonComment(Result&: PeekTok);
284 return false;
285 }
286 }
287 PP.Diag(PeekTok, diag::err_pp_expr_bad_token_start_expr);
288 return true;
289 case tok::eod:
290 case tok::r_paren:
291 // If there is no expression, report and exit.
292 PP.Diag(PeekTok, diag::err_pp_expected_value_in_expr);
293 return true;
294 case tok::numeric_constant: {
295 SmallString<64> IntegerBuffer;
296 bool NumberInvalid = false;
297 StringRef Spelling = PP.getSpelling(Tok: PeekTok, Buffer&: IntegerBuffer,
298 Invalid: &NumberInvalid);
299 if (NumberInvalid)
300 return true; // a diagnostic was already reported
301
302 NumericLiteralParser Literal(Spelling, PeekTok.getLocation(),
303 PP.getSourceManager(), PP.getLangOpts(),
304 PP.getTargetInfo(), PP.getDiagnostics());
305 if (Literal.hadError)
306 return true; // a diagnostic was already reported.
307
308 if (Literal.isFloatingLiteral() || Literal.isImaginary) {
309 PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
310 return true;
311 }
312 assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
313
314 // Complain about, and drop, any ud-suffix.
315 if (Literal.hasUDSuffix())
316 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*integer*/1;
317
318 // 'long long' is a C99 or C++11 feature.
319 if (!PP.getLangOpts().C99 && Literal.isLongLong) {
320 if (PP.getLangOpts().CPlusPlus)
321 PP.Diag(PeekTok,
322 PP.getLangOpts().CPlusPlus11 ?
323 diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
324 else
325 PP.Diag(PeekTok, diag::ext_c99_longlong);
326 }
327
328 // 'z/uz' literals are a C++23 feature.
329 if (Literal.isSizeT)
330 PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus
331 ? PP.getLangOpts().CPlusPlus23
332 ? diag::warn_cxx20_compat_size_t_suffix
333 : diag::ext_cxx23_size_t_suffix
334 : diag::err_cxx23_size_t_suffix);
335
336 // 'wb/uwb' literals are a C23 feature.
337 // '__wb/__uwb' are a C++ extension.
338 if (Literal.isBitInt)
339 PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus ? diag::ext_cxx_bitint_suffix
340 : PP.getLangOpts().C23
341 ? diag::warn_c23_compat_bitint_suffix
342 : diag::ext_c23_bitint_suffix);
343
344 // Parse the integer literal into Result.
345 if (Literal.GetIntegerValue(Val&: Result.Val)) {
346 // Overflow parsing integer literal.
347 if (ValueLive)
348 PP.Diag(PeekTok, diag::err_integer_literal_too_large)
349 << /* Unsigned */ 1;
350 Result.Val.setIsUnsigned(true);
351 } else {
352 // Set the signedness of the result to match whether there was a U suffix
353 // or not.
354 Result.Val.setIsUnsigned(Literal.isUnsigned);
355
356 // Detect overflow based on whether the value is signed. If signed
357 // and if the value is too large, emit a warning "integer constant is so
358 // large that it is unsigned" e.g. on 12345678901234567890 where intmax_t
359 // is 64-bits.
360 if (!Literal.isUnsigned && Result.Val.isNegative()) {
361 // Octal, hexadecimal, and binary literals are implicitly unsigned if
362 // the value does not fit into a signed integer type.
363 if (ValueLive && Literal.getRadix() == 10)
364 PP.Diag(PeekTok, diag::ext_integer_literal_too_large_for_signed);
365 Result.Val.setIsUnsigned(true);
366 }
367 }
368
369 // Consume the token.
370 Result.setRange(PeekTok.getLocation());
371 PP.LexNonComment(Result&: PeekTok);
372 return false;
373 }
374 case tok::char_constant: // 'x'
375 case tok::wide_char_constant: // L'x'
376 case tok::utf8_char_constant: // u8'x'
377 case tok::utf16_char_constant: // u'x'
378 case tok::utf32_char_constant: { // U'x'
379 // Complain about, and drop, any ud-suffix.
380 if (PeekTok.hasUDSuffix())
381 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*character*/0;
382
383 SmallString<32> CharBuffer;
384 bool CharInvalid = false;
385 StringRef ThisTok = PP.getSpelling(Tok: PeekTok, Buffer&: CharBuffer, Invalid: &CharInvalid);
386 if (CharInvalid)
387 return true;
388
389 CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(),
390 PeekTok.getLocation(), PP, PeekTok.getKind());
391 if (Literal.hadError())
392 return true; // A diagnostic was already emitted.
393
394 // Character literals are always int or wchar_t, expand to intmax_t.
395 const TargetInfo &TI = PP.getTargetInfo();
396 unsigned NumBits;
397 if (Literal.isMultiChar())
398 NumBits = TI.getIntWidth();
399 else if (Literal.isWide())
400 NumBits = TI.getWCharWidth();
401 else if (Literal.isUTF16())
402 NumBits = TI.getChar16Width();
403 else if (Literal.isUTF32())
404 NumBits = TI.getChar32Width();
405 else // char or char8_t
406 NumBits = TI.getCharWidth();
407
408 // Set the width.
409 llvm::APSInt Val(NumBits);
410 // Set the value.
411 Val = Literal.getValue();
412 // Set the signedness. UTF-16 and UTF-32 are always unsigned
413 // UTF-8 is unsigned if -fchar8_t is specified.
414 if (Literal.isWide())
415 Val.setIsUnsigned(!TargetInfo::isTypeSigned(T: TI.getWCharType()));
416 else if (Literal.isUTF16() || Literal.isUTF32())
417 Val.setIsUnsigned(true);
418 else if (Literal.isUTF8()) {
419 if (PP.getLangOpts().CPlusPlus)
420 Val.setIsUnsigned(
421 PP.getLangOpts().Char8 ? true : !PP.getLangOpts().CharIsSigned);
422 else
423 Val.setIsUnsigned(true);
424 } else
425 Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned);
426
427 if (Result.Val.getBitWidth() > Val.getBitWidth()) {
428 Result.Val = Val.extend(width: Result.Val.getBitWidth());
429 } else {
430 assert(Result.Val.getBitWidth() == Val.getBitWidth() &&
431 "intmax_t smaller than char/wchar_t?");
432 Result.Val = Val;
433 }
434
435 // Consume the token.
436 Result.setRange(PeekTok.getLocation());
437 PP.LexNonComment(Result&: PeekTok);
438 return false;
439 }
440 case tok::l_paren: {
441 SourceLocation Start = PeekTok.getLocation();
442 PP.LexNonComment(Result&: PeekTok); // Eat the (.
443 // Parse the value and if there are any binary operators involved, parse
444 // them.
445 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
446
447 // If this is a silly value like (X), which doesn't need parens, check for
448 // !(defined X).
449 if (PeekTok.is(K: tok::r_paren)) {
450 // Just use DT unmodified as our result.
451 } else {
452 // Otherwise, we have something like (x+y), and we consumed '(x'.
453 if (EvaluateDirectiveSubExpr(LHS&: Result, MinPrec: 1, PeekTok, ValueLive,
454 IncludedUndefinedIds&: DT.IncludedUndefinedIds, PP))
455 return true;
456
457 if (PeekTok.isNot(K: tok::r_paren)) {
458 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_rparen)
459 << Result.getRange();
460 PP.Diag(Start, diag::note_matching) << tok::l_paren;
461 return true;
462 }
463 DT.State = DefinedTracker::Unknown;
464 }
465 Result.setRange(B: Start, E: PeekTok.getLocation());
466 Result.setIdentifier(nullptr);
467 PP.LexNonComment(Result&: PeekTok); // Eat the ).
468 return false;
469 }
470 case tok::plus: {
471 SourceLocation Start = PeekTok.getLocation();
472 // Unary plus doesn't modify the value.
473 PP.LexNonComment(Result&: PeekTok);
474 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
475 Result.setBegin(Start);
476 Result.setIdentifier(nullptr);
477 return false;
478 }
479 case tok::minus: {
480 SourceLocation Loc = PeekTok.getLocation();
481 PP.LexNonComment(Result&: PeekTok);
482 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
483 Result.setBegin(Loc);
484 Result.setIdentifier(nullptr);
485
486 // C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
487 Result.Val = -Result.Val;
488
489 // -MININT is the only thing that overflows. Unsigned never overflows.
490 bool Overflow = !Result.isUnsigned() && Result.Val.isMinSignedValue();
491
492 // If this operator is live and overflowed, report the issue.
493 if (Overflow && ValueLive)
494 PP.Diag(Loc, diag::warn_pp_expr_overflow) << Result.getRange();
495
496 DT.State = DefinedTracker::Unknown;
497 return false;
498 }
499
500 case tok::tilde: {
501 SourceLocation Start = PeekTok.getLocation();
502 PP.LexNonComment(Result&: PeekTok);
503 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
504 Result.setBegin(Start);
505 Result.setIdentifier(nullptr);
506
507 // C99 6.5.3.3p4: The sign of the result matches the sign of the operand.
508 Result.Val = ~Result.Val;
509 DT.State = DefinedTracker::Unknown;
510 return false;
511 }
512
513 case tok::exclaim: {
514 SourceLocation Start = PeekTok.getLocation();
515 PP.LexNonComment(Result&: PeekTok);
516 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
517 Result.setBegin(Start);
518 Result.Val = !Result.Val;
519 // C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed.
520 Result.Val.setIsUnsigned(false);
521 Result.setIdentifier(nullptr);
522
523 if (DT.State == DefinedTracker::DefinedMacro)
524 DT.State = DefinedTracker::NotDefinedMacro;
525 else if (DT.State == DefinedTracker::NotDefinedMacro)
526 DT.State = DefinedTracker::DefinedMacro;
527 return false;
528 }
529 case tok::kw_true:
530 case tok::kw_false:
531 Result.Val = PeekTok.getKind() == tok::kw_true;
532 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0.
533 Result.setIdentifier(PeekTok.getIdentifierInfo());
534 Result.setRange(PeekTok.getLocation());
535 PP.LexNonComment(Result&: PeekTok);
536 return false;
537
538 // FIXME: Handle #assert
539 }
540}
541
542/// getPrecedence - Return the precedence of the specified binary operator
543/// token. This returns:
544/// ~0 - Invalid token.
545/// 14 -> 3 - various operators.
546/// 0 - 'eod' or ')'
547static unsigned getPrecedence(tok::TokenKind Kind) {
548 switch (Kind) {
549 default: return ~0U;
550 case tok::percent:
551 case tok::slash:
552 case tok::star: return 14;
553 case tok::plus:
554 case tok::minus: return 13;
555 case tok::lessless:
556 case tok::greatergreater: return 12;
557 case tok::lessequal:
558 case tok::less:
559 case tok::greaterequal:
560 case tok::greater: return 11;
561 case tok::exclaimequal:
562 case tok::equalequal: return 10;
563 case tok::amp: return 9;
564 case tok::caret: return 8;
565 case tok::pipe: return 7;
566 case tok::ampamp: return 6;
567 case tok::pipepipe: return 5;
568 case tok::question: return 4;
569 case tok::comma: return 3;
570 case tok::colon: return 2;
571 case tok::r_paren: return 0;// Lowest priority, end of expr.
572 case tok::eod: return 0;// Lowest priority, end of directive.
573 }
574}
575
576static void diagnoseUnexpectedOperator(Preprocessor &PP, PPValue &LHS,
577 Token &Tok) {
578 if (Tok.is(K: tok::l_paren) && LHS.getIdentifier())
579 PP.Diag(LHS.getRange().getBegin(), diag::err_pp_expr_bad_token_lparen)
580 << LHS.getIdentifier();
581 else
582 PP.Diag(Tok.getLocation(), diag::err_pp_expr_bad_token_binop)
583 << LHS.getRange();
584}
585
586/// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is
587/// PeekTok, and whose precedence is PeekPrec. This returns the result in LHS.
588///
589/// If ValueLive is false, then this value is being evaluated in a context where
590/// the result is not used. As such, avoid diagnostics that relate to
591/// evaluation, such as division by zero warnings.
592static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
593 Token &PeekTok, bool ValueLive,
594 bool &IncludedUndefinedIds,
595 Preprocessor &PP) {
596 unsigned PeekPrec = getPrecedence(Kind: PeekTok.getKind());
597 // If this token isn't valid, report the error.
598 if (PeekPrec == ~0U) {
599 diagnoseUnexpectedOperator(PP, LHS, Tok&: PeekTok);
600 return true;
601 }
602
603 while (true) {
604 // If this token has a lower precedence than we are allowed to parse, return
605 // it so that higher levels of the recursion can parse it.
606 if (PeekPrec < MinPrec)
607 return false;
608
609 tok::TokenKind Operator = PeekTok.getKind();
610
611 // If this is a short-circuiting operator, see if the RHS of the operator is
612 // dead. Note that this cannot just clobber ValueLive. Consider
613 // "0 && 1 ? 4 : 1 / 0", which is parsed as "(0 && 1) ? 4 : (1 / 0)". In
614 // this example, the RHS of the && being dead does not make the rest of the
615 // expr dead.
616 bool RHSIsLive;
617 if (Operator == tok::ampamp && LHS.Val == 0)
618 RHSIsLive = false; // RHS of "0 && x" is dead.
619 else if (Operator == tok::pipepipe && LHS.Val != 0)
620 RHSIsLive = false; // RHS of "1 || x" is dead.
621 else if (Operator == tok::question && LHS.Val == 0)
622 RHSIsLive = false; // RHS (x) of "0 ? x : y" is dead.
623 else
624 RHSIsLive = ValueLive;
625
626 // Consume the operator, remembering the operator's location for reporting.
627 SourceLocation OpLoc = PeekTok.getLocation();
628 PP.LexNonComment(Result&: PeekTok);
629
630 PPValue RHS(LHS.getBitWidth());
631 // Parse the RHS of the operator.
632 DefinedTracker DT;
633 if (EvaluateValue(Result&: RHS, PeekTok, DT, ValueLive: RHSIsLive, PP)) return true;
634 IncludedUndefinedIds = DT.IncludedUndefinedIds;
635
636 // Remember the precedence of this operator and get the precedence of the
637 // operator immediately to the right of the RHS.
638 unsigned ThisPrec = PeekPrec;
639 PeekPrec = getPrecedence(Kind: PeekTok.getKind());
640
641 // If this token isn't valid, report the error.
642 if (PeekPrec == ~0U) {
643 diagnoseUnexpectedOperator(PP, LHS&: RHS, Tok&: PeekTok);
644 return true;
645 }
646
647 // Decide whether to include the next binop in this subexpression. For
648 // example, when parsing x+y*z and looking at '*', we want to recursively
649 // handle y*z as a single subexpression. We do this because the precedence
650 // of * is higher than that of +. The only strange case we have to handle
651 // here is for the ?: operator, where the precedence is actually lower than
652 // the LHS of the '?'. The grammar rule is:
653 //
654 // conditional-expression ::=
655 // logical-OR-expression ? expression : conditional-expression
656 // where 'expression' is actually comma-expression.
657 unsigned RHSPrec;
658 if (Operator == tok::question)
659 // The RHS of "?" should be maximally consumed as an expression.
660 RHSPrec = getPrecedence(Kind: tok::comma);
661 else // All others should munch while higher precedence.
662 RHSPrec = ThisPrec+1;
663
664 if (PeekPrec >= RHSPrec) {
665 if (EvaluateDirectiveSubExpr(LHS&: RHS, MinPrec: RHSPrec, PeekTok, ValueLive: RHSIsLive,
666 IncludedUndefinedIds, PP))
667 return true;
668 PeekPrec = getPrecedence(Kind: PeekTok.getKind());
669 }
670 assert(PeekPrec <= ThisPrec && "Recursion didn't work!");
671
672 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
673 // either operand is unsigned.
674 llvm::APSInt Res(LHS.getBitWidth());
675 switch (Operator) {
676 case tok::question: // No UAC for x and y in "x ? y : z".
677 case tok::lessless: // Shift amount doesn't UAC with shift value.
678 case tok::greatergreater: // Shift amount doesn't UAC with shift value.
679 case tok::comma: // Comma operands are not subject to UACs.
680 case tok::pipepipe: // Logical || does not do UACs.
681 case tok::ampamp: // Logical && does not do UACs.
682 break; // No UAC
683 default:
684 Res.setIsUnsigned(LHS.isUnsigned() || RHS.isUnsigned());
685 // If this just promoted something from signed to unsigned, and if the
686 // value was negative, warn about it.
687 if (ValueLive && Res.isUnsigned()) {
688 if (!LHS.isUnsigned() && LHS.Val.isNegative())
689 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 0
690 << toString(I: LHS.Val, Radix: 10, Signed: true) + " to " +
691 toString(I: LHS.Val, Radix: 10, Signed: false)
692 << LHS.getRange() << RHS.getRange();
693 if (!RHS.isUnsigned() && RHS.Val.isNegative())
694 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 1
695 << toString(I: RHS.Val, Radix: 10, Signed: true) + " to " +
696 toString(I: RHS.Val, Radix: 10, Signed: false)
697 << LHS.getRange() << RHS.getRange();
698 }
699 LHS.Val.setIsUnsigned(Res.isUnsigned());
700 RHS.Val.setIsUnsigned(Res.isUnsigned());
701 }
702
703 bool Overflow = false;
704 switch (Operator) {
705 default: llvm_unreachable("Unknown operator token!");
706 case tok::percent:
707 if (RHS.Val != 0)
708 Res = LHS.Val % RHS.Val;
709 else if (ValueLive) {
710 PP.Diag(OpLoc, diag::err_pp_remainder_by_zero)
711 << LHS.getRange() << RHS.getRange();
712 return true;
713 }
714 break;
715 case tok::slash:
716 if (RHS.Val != 0) {
717 if (LHS.Val.isSigned())
718 Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS: RHS.Val, Overflow), false);
719 else
720 Res = LHS.Val / RHS.Val;
721 } else if (ValueLive) {
722 PP.Diag(OpLoc, diag::err_pp_division_by_zero)
723 << LHS.getRange() << RHS.getRange();
724 return true;
725 }
726 break;
727
728 case tok::star:
729 if (Res.isSigned())
730 Res = llvm::APSInt(LHS.Val.smul_ov(RHS: RHS.Val, Overflow), false);
731 else
732 Res = LHS.Val * RHS.Val;
733 break;
734 case tok::lessless: {
735 // Determine whether overflow is about to happen.
736 if (LHS.isUnsigned())
737 Res = LHS.Val.ushl_ov(Amt: RHS.Val, Overflow);
738 else
739 Res = llvm::APSInt(LHS.Val.sshl_ov(Amt: RHS.Val, Overflow), false);
740 break;
741 }
742 case tok::greatergreater: {
743 // Determine whether overflow is about to happen.
744 unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
745 if (ShAmt >= LHS.getBitWidth()) {
746 Overflow = true;
747 ShAmt = LHS.getBitWidth()-1;
748 }
749 Res = LHS.Val >> ShAmt;
750 break;
751 }
752 case tok::plus:
753 if (LHS.isUnsigned())
754 Res = LHS.Val + RHS.Val;
755 else
756 Res = llvm::APSInt(LHS.Val.sadd_ov(RHS: RHS.Val, Overflow), false);
757 break;
758 case tok::minus:
759 if (LHS.isUnsigned())
760 Res = LHS.Val - RHS.Val;
761 else
762 Res = llvm::APSInt(LHS.Val.ssub_ov(RHS: RHS.Val, Overflow), false);
763 break;
764 case tok::lessequal:
765 Res = LHS.Val <= RHS.Val;
766 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
767 break;
768 case tok::less:
769 Res = LHS.Val < RHS.Val;
770 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
771 break;
772 case tok::greaterequal:
773 Res = LHS.Val >= RHS.Val;
774 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
775 break;
776 case tok::greater:
777 Res = LHS.Val > RHS.Val;
778 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
779 break;
780 case tok::exclaimequal:
781 Res = LHS.Val != RHS.Val;
782 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
783 break;
784 case tok::equalequal:
785 Res = LHS.Val == RHS.Val;
786 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
787 break;
788 case tok::amp:
789 Res = LHS.Val & RHS.Val;
790 break;
791 case tok::caret:
792 Res = LHS.Val ^ RHS.Val;
793 break;
794 case tok::pipe:
795 Res = LHS.Val | RHS.Val;
796 break;
797 case tok::ampamp:
798 Res = (LHS.Val != 0 && RHS.Val != 0);
799 Res.setIsUnsigned(false); // C99 6.5.13p3, result is always int (signed)
800 break;
801 case tok::pipepipe:
802 Res = (LHS.Val != 0 || RHS.Val != 0);
803 Res.setIsUnsigned(false); // C99 6.5.14p3, result is always int (signed)
804 break;
805 case tok::comma:
806 // Comma is invalid in pp expressions in c89/c++ mode, but is valid in C99
807 // if not being evaluated.
808 if (!PP.getLangOpts().C99 || ValueLive)
809 PP.Diag(OpLoc, diag::ext_pp_comma_expr)
810 << LHS.getRange() << RHS.getRange();
811 Res = RHS.Val; // LHS = LHS,RHS -> RHS.
812 break;
813 case tok::question: {
814 // Parse the : part of the expression.
815 if (PeekTok.isNot(K: tok::colon)) {
816 PP.Diag(PeekTok.getLocation(), diag::err_expected)
817 << tok::colon << LHS.getRange() << RHS.getRange();
818 PP.Diag(OpLoc, diag::note_matching) << tok::question;
819 return true;
820 }
821 // Consume the :.
822 PP.LexNonComment(Result&: PeekTok);
823
824 // Evaluate the value after the :.
825 bool AfterColonLive = ValueLive && LHS.Val == 0;
826 PPValue AfterColonVal(LHS.getBitWidth());
827 DefinedTracker DT;
828 if (EvaluateValue(Result&: AfterColonVal, PeekTok, DT, ValueLive: AfterColonLive, PP))
829 return true;
830
831 // Parse anything after the : with the same precedence as ?. We allow
832 // things of equal precedence because ?: is right associative.
833 if (EvaluateDirectiveSubExpr(LHS&: AfterColonVal, MinPrec: ThisPrec,
834 PeekTok, ValueLive: AfterColonLive,
835 IncludedUndefinedIds, PP))
836 return true;
837
838 // Now that we have the condition, the LHS and the RHS of the :, evaluate.
839 Res = LHS.Val != 0 ? RHS.Val : AfterColonVal.Val;
840 RHS.setEnd(AfterColonVal.getRange().getEnd());
841
842 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
843 // either operand is unsigned.
844 Res.setIsUnsigned(RHS.isUnsigned() || AfterColonVal.isUnsigned());
845
846 // Figure out the precedence of the token after the : part.
847 PeekPrec = getPrecedence(Kind: PeekTok.getKind());
848 break;
849 }
850 case tok::colon:
851 // Don't allow :'s to float around without being part of ?: exprs.
852 PP.Diag(OpLoc, diag::err_pp_colon_without_question)
853 << LHS.getRange() << RHS.getRange();
854 return true;
855 }
856
857 // If this operator is live and overflowed, report the issue.
858 if (Overflow && ValueLive)
859 PP.Diag(OpLoc, diag::warn_pp_expr_overflow)
860 << LHS.getRange() << RHS.getRange();
861
862 // Put the result back into 'LHS' for our next iteration.
863 LHS.Val = Res;
864 LHS.setEnd(RHS.getRange().getEnd());
865 RHS.setIdentifier(nullptr);
866 }
867}
868
869/// EvaluateDirectiveExpression - Evaluate an integer constant expression that
870/// may occur after a #if or #elif directive. If the expression is equivalent
871/// to "!defined(X)" return X in IfNDefMacro.
872Preprocessor::DirectiveEvalResult
873Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro) {
874 SaveAndRestore PPDir(ParsingIfOrElifDirective, true);
875 // Save the current state of 'DisableMacroExpansion' and reset it to false. If
876 // 'DisableMacroExpansion' is true, then we must be in a macro argument list
877 // in which case a directive is undefined behavior. We want macros to be able
878 // to recursively expand in order to get more gcc-list behavior, so we force
879 // DisableMacroExpansion to false and restore it when we're done parsing the
880 // expression.
881 bool DisableMacroExpansionAtStartOfDirective = DisableMacroExpansion;
882 DisableMacroExpansion = false;
883
884 // Peek ahead one token.
885 Token Tok;
886 LexNonComment(Result&: Tok);
887
888 // C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
889 unsigned BitWidth = getTargetInfo().getIntMaxTWidth();
890
891 PPValue ResVal(BitWidth);
892 DefinedTracker DT;
893 SourceLocation ExprStartLoc = SourceMgr.getExpansionLoc(Loc: Tok.getLocation());
894 if (EvaluateValue(Result&: ResVal, PeekTok&: Tok, DT, ValueLive: true, PP&: *this)) {
895 // Parse error, skip the rest of the macro line.
896 SourceRange ConditionRange = ExprStartLoc;
897 if (Tok.isNot(K: tok::eod))
898 ConditionRange = DiscardUntilEndOfDirective();
899
900 // Restore 'DisableMacroExpansion'.
901 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
902
903 // We cannot trust the source range from the value because there was a
904 // parse error. Track the range manually -- the end of the directive is the
905 // end of the condition range.
906 return {.Conditional: false,
907 .IncludedUndefinedIds: DT.IncludedUndefinedIds,
908 .ExprRange: {ExprStartLoc, ConditionRange.getEnd()}};
909 }
910
911 // If we are at the end of the expression after just parsing a value, there
912 // must be no (unparenthesized) binary operators involved, so we can exit
913 // directly.
914 if (Tok.is(K: tok::eod)) {
915 // If the expression we parsed was of the form !defined(macro), return the
916 // macro in IfNDefMacro.
917 if (DT.State == DefinedTracker::NotDefinedMacro)
918 IfNDefMacro = DT.TheMacro;
919
920 // Restore 'DisableMacroExpansion'.
921 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
922 return {.Conditional: ResVal.Val != 0, .IncludedUndefinedIds: DT.IncludedUndefinedIds, .ExprRange: ResVal.getRange()};
923 }
924
925 // Otherwise, we must have a binary operator (e.g. "#if 1 < 2"), so parse the
926 // operator and the stuff after it.
927 if (EvaluateDirectiveSubExpr(LHS&: ResVal, MinPrec: getPrecedence(Kind: tok::question),
928 PeekTok&: Tok, ValueLive: true, IncludedUndefinedIds&: DT.IncludedUndefinedIds, PP&: *this)) {
929 // Parse error, skip the rest of the macro line.
930 if (Tok.isNot(K: tok::eod))
931 DiscardUntilEndOfDirective();
932
933 // Restore 'DisableMacroExpansion'.
934 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
935 return {.Conditional: false, .IncludedUndefinedIds: DT.IncludedUndefinedIds, .ExprRange: ResVal.getRange()};
936 }
937
938 // If we aren't at the tok::eod token, something bad happened, like an extra
939 // ')' token.
940 if (Tok.isNot(K: tok::eod)) {
941 Diag(Tok, diag::err_pp_expected_eol);
942 DiscardUntilEndOfDirective();
943 }
944
945 // Restore 'DisableMacroExpansion'.
946 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
947 return {.Conditional: ResVal.Val != 0, .IncludedUndefinedIds: DT.IncludedUndefinedIds, .ExprRange: ResVal.getRange()};
948}
949

source code of clang/lib/Lex/PPExpressions.cpp