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1 //===--- PPExpressions.cpp - Preprocessor Expression Evaluation -----------===//
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 Preprocessor::EvaluateDirectiveExpression method,
11 // which parses and evaluates integer constant expressions for #if directives.
12 //
13 //===----------------------------------------------------------------------===//
14 //
15 // FIXME: implement testing for #assert's.
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "clang/Lex/Preprocessor.h"
20 #include "clang/Lex/MacroInfo.h"
21 #include "clang/Lex/LiteralSupport.h"
22 #include "clang/Lex/CodeCompletionHandler.h"
23 #include "clang/Basic/TargetInfo.h"
24 #include "clang/Lex/LexDiagnostic.h"
25 #include "llvm/ADT/APSInt.h"
26 #include "llvm/Support/ErrorHandling.h"
27 using namespace clang;
28 
29 namespace {
30 
31 /// PPValue - Represents the value of a subexpression of a preprocessor
32 /// conditional and the source range covered by it.
33 class PPValue {
34   SourceRange Range;
35 public:
36   llvm::APSInt Val;
37 
38   // Default ctor - Construct an 'invalid' PPValue.
PPValue(unsigned BitWidth)39   PPValue(unsigned BitWidth) : Val(BitWidth) {}
40 
getBitWidth() const41   unsigned getBitWidth() const { return Val.getBitWidth(); }
isUnsigned() const42   bool isUnsigned() const { return Val.isUnsigned(); }
43 
getRange() const44   const SourceRange &getRange() const { return Range; }
45 
setRange(SourceLocation L)46   void setRange(SourceLocation L) { Range.setBegin(L); Range.setEnd(L); }
setRange(SourceLocation B,SourceLocation E)47   void setRange(SourceLocation B, SourceLocation E) {
48     Range.setBegin(B); Range.setEnd(E);
49   }
setBegin(SourceLocation L)50   void setBegin(SourceLocation L) { Range.setBegin(L); }
setEnd(SourceLocation L)51   void setEnd(SourceLocation L) { Range.setEnd(L); }
52 };
53 
54 }
55 
56 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
57                                      Token &PeekTok, bool ValueLive,
58                                      Preprocessor &PP);
59 
60 /// DefinedTracker - This struct is used while parsing expressions to keep track
61 /// of whether !defined(X) has been seen.
62 ///
63 /// With this simple scheme, we handle the basic forms:
64 ///    !defined(X)   and !defined X
65 /// but we also trivially handle (silly) stuff like:
66 ///    !!!defined(X) and +!defined(X) and !+!+!defined(X) and !(defined(X)).
67 struct DefinedTracker {
68   /// Each time a Value is evaluated, it returns information about whether the
69   /// parsed value is of the form defined(X), !defined(X) or is something else.
70   enum TrackerState {
71     DefinedMacro,        // defined(X)
72     NotDefinedMacro,     // !defined(X)
73     Unknown              // Something else.
74   } State;
75   /// TheMacro - When the state is DefinedMacro or NotDefinedMacro, this
76   /// indicates the macro that was checked.
77   IdentifierInfo *TheMacro;
78 };
79 
80 /// EvaluateDefined - Process a 'defined(sym)' expression.
EvaluateDefined(PPValue & Result,Token & PeekTok,DefinedTracker & DT,bool ValueLive,Preprocessor & PP)81 static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
82                             bool ValueLive, Preprocessor &PP) {
83   IdentifierInfo *II;
84   Result.setBegin(PeekTok.getLocation());
85 
86   // Get the next token, don't expand it.
87   PP.LexUnexpandedNonComment(PeekTok);
88 
89   // Two options, it can either be a pp-identifier or a (.
90   SourceLocation LParenLoc;
91   if (PeekTok.is(tok::l_paren)) {
92     // Found a paren, remember we saw it and skip it.
93     LParenLoc = PeekTok.getLocation();
94     PP.LexUnexpandedNonComment(PeekTok);
95   }
96 
97   if (PeekTok.is(tok::code_completion)) {
98     if (PP.getCodeCompletionHandler())
99       PP.getCodeCompletionHandler()->CodeCompleteMacroName(false);
100     PP.setCodeCompletionReached();
101     PP.LexUnexpandedNonComment(PeekTok);
102   }
103 
104   // If we don't have a pp-identifier now, this is an error.
105   if ((II = PeekTok.getIdentifierInfo()) == 0) {
106     PP.Diag(PeekTok, diag::err_pp_defined_requires_identifier);
107     return true;
108   }
109 
110   // Otherwise, we got an identifier, is it defined to something?
111   Result.Val = II->hasMacroDefinition();
112   Result.Val.setIsUnsigned(false);  // Result is signed intmax_t.
113 
114   // If there is a macro, mark it used.
115   if (Result.Val != 0 && ValueLive) {
116     MacroInfo *Macro = PP.getMacroInfo(II);
117     PP.markMacroAsUsed(Macro);
118   }
119 
120   // Invoke the 'defined' callback.
121   if (PPCallbacks *Callbacks = PP.getPPCallbacks())
122     Callbacks->Defined(PeekTok);
123 
124   // If we are in parens, ensure we have a trailing ).
125   if (LParenLoc.isValid()) {
126     // Consume identifier.
127     Result.setEnd(PeekTok.getLocation());
128     PP.LexUnexpandedNonComment(PeekTok);
129 
130     if (PeekTok.isNot(tok::r_paren)) {
131       PP.Diag(PeekTok.getLocation(), diag::err_pp_missing_rparen) << "defined";
132       PP.Diag(LParenLoc, diag::note_matching) << "(";
133       return true;
134     }
135     // Consume the ).
136     Result.setEnd(PeekTok.getLocation());
137     PP.LexNonComment(PeekTok);
138   } else {
139     // Consume identifier.
140     Result.setEnd(PeekTok.getLocation());
141     PP.LexNonComment(PeekTok);
142   }
143 
144   // Success, remember that we saw defined(X).
145   DT.State = DefinedTracker::DefinedMacro;
146   DT.TheMacro = II;
147   return false;
148 }
149 
150 /// EvaluateValue - Evaluate the token PeekTok (and any others needed) and
151 /// return the computed value in Result.  Return true if there was an error
152 /// parsing.  This function also returns information about the form of the
153 /// expression in DT.  See above for information on what DT means.
154 ///
155 /// If ValueLive is false, then this value is being evaluated in a context where
156 /// the result is not used.  As such, avoid diagnostics that relate to
157 /// evaluation.
EvaluateValue(PPValue & Result,Token & PeekTok,DefinedTracker & DT,bool ValueLive,Preprocessor & PP)158 static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
159                           bool ValueLive, Preprocessor &PP) {
160   DT.State = DefinedTracker::Unknown;
161 
162   if (PeekTok.is(tok::code_completion)) {
163     if (PP.getCodeCompletionHandler())
164       PP.getCodeCompletionHandler()->CodeCompletePreprocessorExpression();
165     PP.setCodeCompletionReached();
166     PP.LexNonComment(PeekTok);
167   }
168 
169   // If this token's spelling is a pp-identifier, check to see if it is
170   // 'defined' or if it is a macro.  Note that we check here because many
171   // keywords are pp-identifiers, so we can't check the kind.
172   if (IdentifierInfo *II = PeekTok.getIdentifierInfo()) {
173     // Handle "defined X" and "defined(X)".
174     if (II->isStr("defined"))
175       return(EvaluateDefined(Result, PeekTok, DT, ValueLive, PP));
176 
177     // If this identifier isn't 'defined' or one of the special
178     // preprocessor keywords and it wasn't macro expanded, it turns
179     // into a simple 0, unless it is the C++ keyword "true", in which case it
180     // turns into "1".
181     if (ValueLive)
182       PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II;
183     Result.Val = II->getTokenID() == tok::kw_true;
184     Result.Val.setIsUnsigned(false);  // "0" is signed intmax_t 0.
185     Result.setRange(PeekTok.getLocation());
186     PP.LexNonComment(PeekTok);
187     return false;
188   }
189 
190   switch (PeekTok.getKind()) {
191   default:  // Non-value token.
192     PP.Diag(PeekTok, diag::err_pp_expr_bad_token_start_expr);
193     return true;
194   case tok::eod:
195   case tok::r_paren:
196     // If there is no expression, report and exit.
197     PP.Diag(PeekTok, diag::err_pp_expected_value_in_expr);
198     return true;
199   case tok::numeric_constant: {
200     SmallString<64> IntegerBuffer;
201     bool NumberInvalid = false;
202     StringRef Spelling = PP.getSpelling(PeekTok, IntegerBuffer,
203                                               &NumberInvalid);
204     if (NumberInvalid)
205       return true; // a diagnostic was already reported
206 
207     NumericLiteralParser Literal(Spelling.begin(), Spelling.end(),
208                                  PeekTok.getLocation(), PP);
209     if (Literal.hadError)
210       return true; // a diagnostic was already reported.
211 
212     if (Literal.isFloatingLiteral() || Literal.isImaginary) {
213       PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
214       return true;
215     }
216     assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
217 
218     // Complain about, and drop, any ud-suffix.
219     if (Literal.hasUDSuffix())
220       PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*integer*/1;
221 
222     // long long is a C99 feature.
223     if (!PP.getLangOpts().C99 && Literal.isLongLong)
224       PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus0x ?
225               diag::warn_cxx98_compat_longlong : diag::ext_longlong);
226 
227     // Parse the integer literal into Result.
228     if (Literal.GetIntegerValue(Result.Val)) {
229       // Overflow parsing integer literal.
230       if (ValueLive) PP.Diag(PeekTok, diag::warn_integer_too_large);
231       Result.Val.setIsUnsigned(true);
232     } else {
233       // Set the signedness of the result to match whether there was a U suffix
234       // or not.
235       Result.Val.setIsUnsigned(Literal.isUnsigned);
236 
237       // Detect overflow based on whether the value is signed.  If signed
238       // and if the value is too large, emit a warning "integer constant is so
239       // large that it is unsigned" e.g. on 12345678901234567890 where intmax_t
240       // is 64-bits.
241       if (!Literal.isUnsigned && Result.Val.isNegative()) {
242         // Don't warn for a hex literal: 0x8000..0 shouldn't warn.
243         if (ValueLive && Literal.getRadix() != 16)
244           PP.Diag(PeekTok, diag::warn_integer_too_large_for_signed);
245         Result.Val.setIsUnsigned(true);
246       }
247     }
248 
249     // Consume the token.
250     Result.setRange(PeekTok.getLocation());
251     PP.LexNonComment(PeekTok);
252     return false;
253   }
254   case tok::char_constant:          // 'x'
255   case tok::wide_char_constant: {   // L'x'
256   case tok::utf16_char_constant:    // u'x'
257   case tok::utf32_char_constant:    // U'x'
258     // Complain about, and drop, any ud-suffix.
259     if (PeekTok.hasUDSuffix())
260       PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*character*/0;
261 
262     SmallString<32> CharBuffer;
263     bool CharInvalid = false;
264     StringRef ThisTok = PP.getSpelling(PeekTok, CharBuffer, &CharInvalid);
265     if (CharInvalid)
266       return true;
267 
268     CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(),
269                               PeekTok.getLocation(), PP, PeekTok.getKind());
270     if (Literal.hadError())
271       return true;  // A diagnostic was already emitted.
272 
273     // Character literals are always int or wchar_t, expand to intmax_t.
274     const TargetInfo &TI = PP.getTargetInfo();
275     unsigned NumBits;
276     if (Literal.isMultiChar())
277       NumBits = TI.getIntWidth();
278     else if (Literal.isWide())
279       NumBits = TI.getWCharWidth();
280     else if (Literal.isUTF16())
281       NumBits = TI.getChar16Width();
282     else if (Literal.isUTF32())
283       NumBits = TI.getChar32Width();
284     else
285       NumBits = TI.getCharWidth();
286 
287     // Set the width.
288     llvm::APSInt Val(NumBits);
289     // Set the value.
290     Val = Literal.getValue();
291     // Set the signedness. UTF-16 and UTF-32 are always unsigned
292     if (!Literal.isUTF16() && !Literal.isUTF32())
293       Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned);
294 
295     if (Result.Val.getBitWidth() > Val.getBitWidth()) {
296       Result.Val = Val.extend(Result.Val.getBitWidth());
297     } else {
298       assert(Result.Val.getBitWidth() == Val.getBitWidth() &&
299              "intmax_t smaller than char/wchar_t?");
300       Result.Val = Val;
301     }
302 
303     // Consume the token.
304     Result.setRange(PeekTok.getLocation());
305     PP.LexNonComment(PeekTok);
306     return false;
307   }
308   case tok::l_paren: {
309     SourceLocation Start = PeekTok.getLocation();
310     PP.LexNonComment(PeekTok);  // Eat the (.
311     // Parse the value and if there are any binary operators involved, parse
312     // them.
313     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
314 
315     // If this is a silly value like (X), which doesn't need parens, check for
316     // !(defined X).
317     if (PeekTok.is(tok::r_paren)) {
318       // Just use DT unmodified as our result.
319     } else {
320       // Otherwise, we have something like (x+y), and we consumed '(x'.
321       if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive, PP))
322         return true;
323 
324       if (PeekTok.isNot(tok::r_paren)) {
325         PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_rparen)
326           << Result.getRange();
327         PP.Diag(Start, diag::note_matching) << "(";
328         return true;
329       }
330       DT.State = DefinedTracker::Unknown;
331     }
332     Result.setRange(Start, PeekTok.getLocation());
333     PP.LexNonComment(PeekTok);  // Eat the ).
334     return false;
335   }
336   case tok::plus: {
337     SourceLocation Start = PeekTok.getLocation();
338     // Unary plus doesn't modify the value.
339     PP.LexNonComment(PeekTok);
340     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
341     Result.setBegin(Start);
342     return false;
343   }
344   case tok::minus: {
345     SourceLocation Loc = PeekTok.getLocation();
346     PP.LexNonComment(PeekTok);
347     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
348     Result.setBegin(Loc);
349 
350     // C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
351     Result.Val = -Result.Val;
352 
353     // -MININT is the only thing that overflows.  Unsigned never overflows.
354     bool Overflow = !Result.isUnsigned() && Result.Val.isMinSignedValue();
355 
356     // If this operator is live and overflowed, report the issue.
357     if (Overflow && ValueLive)
358       PP.Diag(Loc, diag::warn_pp_expr_overflow) << Result.getRange();
359 
360     DT.State = DefinedTracker::Unknown;
361     return false;
362   }
363 
364   case tok::tilde: {
365     SourceLocation Start = PeekTok.getLocation();
366     PP.LexNonComment(PeekTok);
367     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
368     Result.setBegin(Start);
369 
370     // C99 6.5.3.3p4: The sign of the result matches the sign of the operand.
371     Result.Val = ~Result.Val;
372     DT.State = DefinedTracker::Unknown;
373     return false;
374   }
375 
376   case tok::exclaim: {
377     SourceLocation Start = PeekTok.getLocation();
378     PP.LexNonComment(PeekTok);
379     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
380     Result.setBegin(Start);
381     Result.Val = !Result.Val;
382     // C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed.
383     Result.Val.setIsUnsigned(false);
384 
385     if (DT.State == DefinedTracker::DefinedMacro)
386       DT.State = DefinedTracker::NotDefinedMacro;
387     else if (DT.State == DefinedTracker::NotDefinedMacro)
388       DT.State = DefinedTracker::DefinedMacro;
389     return false;
390   }
391 
392   // FIXME: Handle #assert
393   }
394 }
395 
396 
397 
398 /// getPrecedence - Return the precedence of the specified binary operator
399 /// token.  This returns:
400 ///   ~0 - Invalid token.
401 ///   14 -> 3 - various operators.
402 ///    0 - 'eod' or ')'
getPrecedence(tok::TokenKind Kind)403 static unsigned getPrecedence(tok::TokenKind Kind) {
404   switch (Kind) {
405   default: return ~0U;
406   case tok::percent:
407   case tok::slash:
408   case tok::star:                 return 14;
409   case tok::plus:
410   case tok::minus:                return 13;
411   case tok::lessless:
412   case tok::greatergreater:       return 12;
413   case tok::lessequal:
414   case tok::less:
415   case tok::greaterequal:
416   case tok::greater:              return 11;
417   case tok::exclaimequal:
418   case tok::equalequal:           return 10;
419   case tok::amp:                  return 9;
420   case tok::caret:                return 8;
421   case tok::pipe:                 return 7;
422   case tok::ampamp:               return 6;
423   case tok::pipepipe:             return 5;
424   case tok::question:             return 4;
425   case tok::comma:                return 3;
426   case tok::colon:                return 2;
427   case tok::r_paren:              return 0;// Lowest priority, end of expr.
428   case tok::eod:                  return 0;// Lowest priority, end of directive.
429   }
430 }
431 
432 
433 /// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is
434 /// PeekTok, and whose precedence is PeekPrec.  This returns the result in LHS.
435 ///
436 /// If ValueLive is false, then this value is being evaluated in a context where
437 /// the result is not used.  As such, avoid diagnostics that relate to
438 /// evaluation, such as division by zero warnings.
EvaluateDirectiveSubExpr(PPValue & LHS,unsigned MinPrec,Token & PeekTok,bool ValueLive,Preprocessor & PP)439 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
440                                      Token &PeekTok, bool ValueLive,
441                                      Preprocessor &PP) {
442   unsigned PeekPrec = getPrecedence(PeekTok.getKind());
443   // If this token isn't valid, report the error.
444   if (PeekPrec == ~0U) {
445     PP.Diag(PeekTok.getLocation(), diag::err_pp_expr_bad_token_binop)
446       << LHS.getRange();
447     return true;
448   }
449 
450   while (1) {
451     // If this token has a lower precedence than we are allowed to parse, return
452     // it so that higher levels of the recursion can parse it.
453     if (PeekPrec < MinPrec)
454       return false;
455 
456     tok::TokenKind Operator = PeekTok.getKind();
457 
458     // If this is a short-circuiting operator, see if the RHS of the operator is
459     // dead.  Note that this cannot just clobber ValueLive.  Consider
460     // "0 && 1 ? 4 : 1 / 0", which is parsed as "(0 && 1) ? 4 : (1 / 0)".  In
461     // this example, the RHS of the && being dead does not make the rest of the
462     // expr dead.
463     bool RHSIsLive;
464     if (Operator == tok::ampamp && LHS.Val == 0)
465       RHSIsLive = false;   // RHS of "0 && x" is dead.
466     else if (Operator == tok::pipepipe && LHS.Val != 0)
467       RHSIsLive = false;   // RHS of "1 || x" is dead.
468     else if (Operator == tok::question && LHS.Val == 0)
469       RHSIsLive = false;   // RHS (x) of "0 ? x : y" is dead.
470     else
471       RHSIsLive = ValueLive;
472 
473     // Consume the operator, remembering the operator's location for reporting.
474     SourceLocation OpLoc = PeekTok.getLocation();
475     PP.LexNonComment(PeekTok);
476 
477     PPValue RHS(LHS.getBitWidth());
478     // Parse the RHS of the operator.
479     DefinedTracker DT;
480     if (EvaluateValue(RHS, PeekTok, DT, RHSIsLive, PP)) return true;
481 
482     // Remember the precedence of this operator and get the precedence of the
483     // operator immediately to the right of the RHS.
484     unsigned ThisPrec = PeekPrec;
485     PeekPrec = getPrecedence(PeekTok.getKind());
486 
487     // If this token isn't valid, report the error.
488     if (PeekPrec == ~0U) {
489       PP.Diag(PeekTok.getLocation(), diag::err_pp_expr_bad_token_binop)
490         << RHS.getRange();
491       return true;
492     }
493 
494     // Decide whether to include the next binop in this subexpression.  For
495     // example, when parsing x+y*z and looking at '*', we want to recursively
496     // handle y*z as a single subexpression.  We do this because the precedence
497     // of * is higher than that of +.  The only strange case we have to handle
498     // here is for the ?: operator, where the precedence is actually lower than
499     // the LHS of the '?'.  The grammar rule is:
500     //
501     // conditional-expression ::=
502     //    logical-OR-expression ? expression : conditional-expression
503     // where 'expression' is actually comma-expression.
504     unsigned RHSPrec;
505     if (Operator == tok::question)
506       // The RHS of "?" should be maximally consumed as an expression.
507       RHSPrec = getPrecedence(tok::comma);
508     else  // All others should munch while higher precedence.
509       RHSPrec = ThisPrec+1;
510 
511     if (PeekPrec >= RHSPrec) {
512       if (EvaluateDirectiveSubExpr(RHS, RHSPrec, PeekTok, RHSIsLive, PP))
513         return true;
514       PeekPrec = getPrecedence(PeekTok.getKind());
515     }
516     assert(PeekPrec <= ThisPrec && "Recursion didn't work!");
517 
518     // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
519     // either operand is unsigned.
520     llvm::APSInt Res(LHS.getBitWidth());
521     switch (Operator) {
522     case tok::question:       // No UAC for x and y in "x ? y : z".
523     case tok::lessless:       // Shift amount doesn't UAC with shift value.
524     case tok::greatergreater: // Shift amount doesn't UAC with shift value.
525     case tok::comma:          // Comma operands are not subject to UACs.
526     case tok::pipepipe:       // Logical || does not do UACs.
527     case tok::ampamp:         // Logical && does not do UACs.
528       break;                  // No UAC
529     default:
530       Res.setIsUnsigned(LHS.isUnsigned()|RHS.isUnsigned());
531       // If this just promoted something from signed to unsigned, and if the
532       // value was negative, warn about it.
533       if (ValueLive && Res.isUnsigned()) {
534         if (!LHS.isUnsigned() && LHS.Val.isNegative())
535           PP.Diag(OpLoc, diag::warn_pp_convert_lhs_to_positive)
536             << LHS.Val.toString(10, true) + " to " +
537                LHS.Val.toString(10, false)
538             << LHS.getRange() << RHS.getRange();
539         if (!RHS.isUnsigned() && RHS.Val.isNegative())
540           PP.Diag(OpLoc, diag::warn_pp_convert_rhs_to_positive)
541             << RHS.Val.toString(10, true) + " to " +
542                RHS.Val.toString(10, false)
543             << LHS.getRange() << RHS.getRange();
544       }
545       LHS.Val.setIsUnsigned(Res.isUnsigned());
546       RHS.Val.setIsUnsigned(Res.isUnsigned());
547     }
548 
549     bool Overflow = false;
550     switch (Operator) {
551     default: llvm_unreachable("Unknown operator token!");
552     case tok::percent:
553       if (RHS.Val != 0)
554         Res = LHS.Val % RHS.Val;
555       else if (ValueLive) {
556         PP.Diag(OpLoc, diag::err_pp_remainder_by_zero)
557           << LHS.getRange() << RHS.getRange();
558         return true;
559       }
560       break;
561     case tok::slash:
562       if (RHS.Val != 0) {
563         if (LHS.Val.isSigned())
564           Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS.Val, Overflow), false);
565         else
566           Res = LHS.Val / RHS.Val;
567       } else if (ValueLive) {
568         PP.Diag(OpLoc, diag::err_pp_division_by_zero)
569           << LHS.getRange() << RHS.getRange();
570         return true;
571       }
572       break;
573 
574     case tok::star:
575       if (Res.isSigned())
576         Res = llvm::APSInt(LHS.Val.smul_ov(RHS.Val, Overflow), false);
577       else
578         Res = LHS.Val * RHS.Val;
579       break;
580     case tok::lessless: {
581       // Determine whether overflow is about to happen.
582       unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
583       if (LHS.isUnsigned()) {
584         Overflow = ShAmt >= LHS.Val.getBitWidth();
585         if (Overflow)
586           ShAmt = LHS.Val.getBitWidth()-1;
587         Res = LHS.Val << ShAmt;
588       } else {
589         Res = llvm::APSInt(LHS.Val.sshl_ov(ShAmt, Overflow), false);
590       }
591       break;
592     }
593     case tok::greatergreater: {
594       // Determine whether overflow is about to happen.
595       unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
596       if (ShAmt >= LHS.getBitWidth())
597         Overflow = true, ShAmt = LHS.getBitWidth()-1;
598       Res = LHS.Val >> ShAmt;
599       break;
600     }
601     case tok::plus:
602       if (LHS.isUnsigned())
603         Res = LHS.Val + RHS.Val;
604       else
605         Res = llvm::APSInt(LHS.Val.sadd_ov(RHS.Val, Overflow), false);
606       break;
607     case tok::minus:
608       if (LHS.isUnsigned())
609         Res = LHS.Val - RHS.Val;
610       else
611         Res = llvm::APSInt(LHS.Val.ssub_ov(RHS.Val, Overflow), false);
612       break;
613     case tok::lessequal:
614       Res = LHS.Val <= RHS.Val;
615       Res.setIsUnsigned(false);  // C99 6.5.8p6, result is always int (signed)
616       break;
617     case tok::less:
618       Res = LHS.Val < RHS.Val;
619       Res.setIsUnsigned(false);  // C99 6.5.8p6, result is always int (signed)
620       break;
621     case tok::greaterequal:
622       Res = LHS.Val >= RHS.Val;
623       Res.setIsUnsigned(false);  // C99 6.5.8p6, result is always int (signed)
624       break;
625     case tok::greater:
626       Res = LHS.Val > RHS.Val;
627       Res.setIsUnsigned(false);  // C99 6.5.8p6, result is always int (signed)
628       break;
629     case tok::exclaimequal:
630       Res = LHS.Val != RHS.Val;
631       Res.setIsUnsigned(false);  // C99 6.5.9p3, result is always int (signed)
632       break;
633     case tok::equalequal:
634       Res = LHS.Val == RHS.Val;
635       Res.setIsUnsigned(false);  // C99 6.5.9p3, result is always int (signed)
636       break;
637     case tok::amp:
638       Res = LHS.Val & RHS.Val;
639       break;
640     case tok::caret:
641       Res = LHS.Val ^ RHS.Val;
642       break;
643     case tok::pipe:
644       Res = LHS.Val | RHS.Val;
645       break;
646     case tok::ampamp:
647       Res = (LHS.Val != 0 && RHS.Val != 0);
648       Res.setIsUnsigned(false);  // C99 6.5.13p3, result is always int (signed)
649       break;
650     case tok::pipepipe:
651       Res = (LHS.Val != 0 || RHS.Val != 0);
652       Res.setIsUnsigned(false);  // C99 6.5.14p3, result is always int (signed)
653       break;
654     case tok::comma:
655       // Comma is invalid in pp expressions in c89/c++ mode, but is valid in C99
656       // if not being evaluated.
657       if (!PP.getLangOpts().C99 || ValueLive)
658         PP.Diag(OpLoc, diag::ext_pp_comma_expr)
659           << LHS.getRange() << RHS.getRange();
660       Res = RHS.Val; // LHS = LHS,RHS -> RHS.
661       break;
662     case tok::question: {
663       // Parse the : part of the expression.
664       if (PeekTok.isNot(tok::colon)) {
665         PP.Diag(PeekTok.getLocation(), diag::err_expected_colon)
666           << LHS.getRange(), RHS.getRange();
667         PP.Diag(OpLoc, diag::note_matching) << "?";
668         return true;
669       }
670       // Consume the :.
671       PP.LexNonComment(PeekTok);
672 
673       // Evaluate the value after the :.
674       bool AfterColonLive = ValueLive && LHS.Val == 0;
675       PPValue AfterColonVal(LHS.getBitWidth());
676       DefinedTracker DT;
677       if (EvaluateValue(AfterColonVal, PeekTok, DT, AfterColonLive, PP))
678         return true;
679 
680       // Parse anything after the : with the same precedence as ?.  We allow
681       // things of equal precedence because ?: is right associative.
682       if (EvaluateDirectiveSubExpr(AfterColonVal, ThisPrec,
683                                    PeekTok, AfterColonLive, PP))
684         return true;
685 
686       // Now that we have the condition, the LHS and the RHS of the :, evaluate.
687       Res = LHS.Val != 0 ? RHS.Val : AfterColonVal.Val;
688       RHS.setEnd(AfterColonVal.getRange().getEnd());
689 
690       // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
691       // either operand is unsigned.
692       Res.setIsUnsigned(RHS.isUnsigned() | AfterColonVal.isUnsigned());
693 
694       // Figure out the precedence of the token after the : part.
695       PeekPrec = getPrecedence(PeekTok.getKind());
696       break;
697     }
698     case tok::colon:
699       // Don't allow :'s to float around without being part of ?: exprs.
700       PP.Diag(OpLoc, diag::err_pp_colon_without_question)
701         << LHS.getRange() << RHS.getRange();
702       return true;
703     }
704 
705     // If this operator is live and overflowed, report the issue.
706     if (Overflow && ValueLive)
707       PP.Diag(OpLoc, diag::warn_pp_expr_overflow)
708         << LHS.getRange() << RHS.getRange();
709 
710     // Put the result back into 'LHS' for our next iteration.
711     LHS.Val = Res;
712     LHS.setEnd(RHS.getRange().getEnd());
713   }
714 }
715 
716 /// EvaluateDirectiveExpression - Evaluate an integer constant expression that
717 /// may occur after a #if or #elif directive.  If the expression is equivalent
718 /// to "!defined(X)" return X in IfNDefMacro.
719 bool Preprocessor::
EvaluateDirectiveExpression(IdentifierInfo * & IfNDefMacro)720 EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro) {
721   // Save the current state of 'DisableMacroExpansion' and reset it to false. If
722   // 'DisableMacroExpansion' is true, then we must be in a macro argument list
723   // in which case a directive is undefined behavior.  We want macros to be able
724   // to recursively expand in order to get more gcc-list behavior, so we force
725   // DisableMacroExpansion to false and restore it when we're done parsing the
726   // expression.
727   bool DisableMacroExpansionAtStartOfDirective = DisableMacroExpansion;
728   DisableMacroExpansion = false;
729 
730   // Peek ahead one token.
731   Token Tok;
732   LexNonComment(Tok);
733 
734   // C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
735   unsigned BitWidth = getTargetInfo().getIntMaxTWidth();
736 
737   PPValue ResVal(BitWidth);
738   DefinedTracker DT;
739   if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
740     // Parse error, skip the rest of the macro line.
741     if (Tok.isNot(tok::eod))
742       DiscardUntilEndOfDirective();
743 
744     // Restore 'DisableMacroExpansion'.
745     DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
746     return false;
747   }
748 
749   // If we are at the end of the expression after just parsing a value, there
750   // must be no (unparenthesized) binary operators involved, so we can exit
751   // directly.
752   if (Tok.is(tok::eod)) {
753     // If the expression we parsed was of the form !defined(macro), return the
754     // macro in IfNDefMacro.
755     if (DT.State == DefinedTracker::NotDefinedMacro)
756       IfNDefMacro = DT.TheMacro;
757 
758     // Restore 'DisableMacroExpansion'.
759     DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
760     return ResVal.Val != 0;
761   }
762 
763   // Otherwise, we must have a binary operator (e.g. "#if 1 < 2"), so parse the
764   // operator and the stuff after it.
765   if (EvaluateDirectiveSubExpr(ResVal, getPrecedence(tok::question),
766                                Tok, true, *this)) {
767     // Parse error, skip the rest of the macro line.
768     if (Tok.isNot(tok::eod))
769       DiscardUntilEndOfDirective();
770 
771     // Restore 'DisableMacroExpansion'.
772     DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
773     return false;
774   }
775 
776   // If we aren't at the tok::eod token, something bad happened, like an extra
777   // ')' token.
778   if (Tok.isNot(tok::eod)) {
779     Diag(Tok, diag::err_pp_expected_eol);
780     DiscardUntilEndOfDirective();
781   }
782 
783   // Restore 'DisableMacroExpansion'.
784   DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
785   return ResVal.Val != 0;
786 }
787