Stage two of getting CFE top correct.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@39734 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Lex/PPExpressions.cpp b/Lex/PPExpressions.cpp
new file mode 100644
index 0000000..b3457e7
--- /dev/null
+++ b/Lex/PPExpressions.cpp
@@ -0,0 +1,654 @@
+//===--- PPExpressions.cpp - Preprocessor Expression Evaluation -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Preprocessor::EvaluateDirectiveExpression method,
+// which parses and evaluates integer constant expressions for #if directives.
+//
+//===----------------------------------------------------------------------===//
+//
+// FIXME: implement testing for #assert's.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/LiteralSupport.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Basic/TokenKinds.h"
+#include "clang/Basic/Diagnostic.h"
+#include "llvm/ADT/APSInt.h"
+#include "llvm/ADT/SmallString.h"
+using namespace clang;
+
+static bool EvaluateDirectiveSubExpr(llvm::APSInt &LHS, unsigned MinPrec,
+ LexerToken &PeekTok, bool ValueLive,
+ Preprocessor &PP);
+
+/// DefinedTracker - This struct is used while parsing expressions to keep track
+/// of whether !defined(X) has been seen.
+///
+/// With this simple scheme, we handle the basic forms:
+/// !defined(X) and !defined X
+/// but we also trivially handle (silly) stuff like:
+/// !!!defined(X) and +!defined(X) and !+!+!defined(X) and !(defined(X)).
+struct DefinedTracker {
+ /// Each time a Value is evaluated, it returns information about whether the
+ /// parsed value is of the form defined(X), !defined(X) or is something else.
+ enum TrackerState {
+ DefinedMacro, // defined(X)
+ NotDefinedMacro, // !defined(X)
+ Unknown // Something else.
+ } State;
+ /// TheMacro - When the state is DefinedMacro or NotDefinedMacro, this
+ /// indicates the macro that was checked.
+ IdentifierInfo *TheMacro;
+};
+
+
+
+/// EvaluateValue - Evaluate the token PeekTok (and any others needed) and
+/// return the computed value in Result. Return true if there was an error
+/// parsing. This function also returns information about the form of the
+/// expression in DT. See above for information on what DT means.
+///
+/// If ValueLive is false, then this value is being evaluated in a context where
+/// the result is not used. As such, avoid diagnostics that relate to
+/// evaluation.
+static bool EvaluateValue(llvm::APSInt &Result, LexerToken &PeekTok,
+ DefinedTracker &DT, bool ValueLive,
+ Preprocessor &PP) {
+ Result = 0;
+ DT.State = DefinedTracker::Unknown;
+
+ // If this token's spelling is a pp-identifier, check to see if it is
+ // 'defined' or if it is a macro. Note that we check here because many
+ // keywords are pp-identifiers, so we can't check the kind.
+ if (IdentifierInfo *II = PeekTok.getIdentifierInfo()) {
+ // If this identifier isn't 'defined' and it wasn't macro expanded, it turns
+ // into a simple 0, unless it is the C++ keyword "true", in which case it
+ // turns into "1".
+ if (II->getPPKeywordID() != tok::pp_defined) {
+ Result = II->getTokenID() == tok::kw_true;
+ Result.setIsUnsigned(false); // "0" is signed intmax_t 0.
+ PP.LexNonComment(PeekTok);
+ return false;
+ }
+
+ // Handle "defined X" and "defined(X)".
+
+ // Get the next token, don't expand it.
+ PP.LexUnexpandedToken(PeekTok);
+
+ // Two options, it can either be a pp-identifier or a (.
+ bool InParens = false;
+ if (PeekTok.getKind() == tok::l_paren) {
+ // Found a paren, remember we saw it and skip it.
+ InParens = true;
+ PP.LexUnexpandedToken(PeekTok);
+ }
+
+ // If we don't have a pp-identifier now, this is an error.
+ if ((II = PeekTok.getIdentifierInfo()) == 0) {
+ PP.Diag(PeekTok, diag::err_pp_defined_requires_identifier);
+ return true;
+ }
+
+ // Otherwise, we got an identifier, is it defined to something?
+ Result = II->getMacroInfo() != 0;
+ Result.setIsUnsigned(false); // Result is signed intmax_t.
+
+ // If there is a macro, mark it used.
+ if (Result != 0 && ValueLive) {
+ II->getMacroInfo()->setIsUsed(true);
+
+ // If this is the first use of a target-specific macro, warn about it.
+ if (II->getMacroInfo()->isTargetSpecific()) {
+ // Don't warn on second use.
+ II->getMacroInfo()->setIsTargetSpecific(false);
+ PP.getTargetInfo().DiagnoseNonPortability(PeekTok.getLocation(),
+ diag::port_target_macro_use);
+ }
+ } else if (ValueLive) {
+ // Use of a target-specific macro for some other target? If so, warn.
+ if (II->isOtherTargetMacro()) {
+ II->setIsOtherTargetMacro(false); // Don't warn on second use.
+ PP.getTargetInfo().DiagnoseNonPortability(PeekTok.getLocation(),
+ diag::port_target_macro_use);
+ }
+ }
+
+ // Consume identifier.
+ PP.LexNonComment(PeekTok);
+
+ // If we are in parens, ensure we have a trailing ).
+ if (InParens) {
+ if (PeekTok.getKind() != tok::r_paren) {
+ PP.Diag(PeekTok, diag::err_pp_missing_rparen);
+ return true;
+ }
+ // Consume the ).
+ PP.LexNonComment(PeekTok);
+ }
+
+ // Success, remember that we saw defined(X).
+ DT.State = DefinedTracker::DefinedMacro;
+ DT.TheMacro = II;
+ return false;
+ }
+
+ switch (PeekTok.getKind()) {
+ default: // Non-value token.
+ PP.Diag(PeekTok, diag::err_pp_expr_bad_token);
+ return true;
+ case tok::eom:
+ case tok::r_paren:
+ // If there is no expression, report and exit.
+ PP.Diag(PeekTok, diag::err_pp_expected_value_in_expr);
+ return true;
+ case tok::numeric_constant: {
+ llvm::SmallString<64> IntegerBuffer;
+ IntegerBuffer.resize(PeekTok.getLength());
+ const char *ThisTokBegin = &IntegerBuffer[0];
+ unsigned ActualLength = PP.getSpelling(PeekTok, ThisTokBegin);
+ NumericLiteralParser Literal(ThisTokBegin, ThisTokBegin+ActualLength,
+ PeekTok.getLocation(), PP);
+ if (Literal.hadError)
+ return true; // a diagnostic was already reported.
+
+ if (Literal.isFloatingLiteral()) {
+ PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
+ return true;
+ }
+ assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
+
+ // Parse the integer literal into Result.
+ if (Literal.GetIntegerValue(Result)) {
+ // Overflow parsing integer literal.
+ if (ValueLive) PP.Diag(PeekTok, diag::warn_integer_too_large);
+ Result.setIsUnsigned(true);
+ } else {
+ // Set the signedness of the result to match whether there was a U suffix
+ // or not.
+ Result.setIsUnsigned(Literal.isUnsigned);
+
+ // Detect overflow based on whether the value is signed. If signed
+ // and if the value is too large, emit a warning "integer constant is so
+ // large that it is unsigned" e.g. on 12345678901234567890 where intmax_t
+ // is 64-bits.
+ if (!Literal.isUnsigned && Result.isNegative()) {
+ if (ValueLive)PP.Diag(PeekTok, diag::warn_integer_too_large_for_signed);
+ Result.setIsUnsigned(true);
+ }
+ }
+
+ // Consume the token.
+ PP.LexNonComment(PeekTok);
+ return false;
+ }
+ case tok::char_constant: { // 'x'
+ llvm::SmallString<32> CharBuffer;
+ CharBuffer.resize(PeekTok.getLength());
+ const char *ThisTokBegin = &CharBuffer[0];
+ unsigned ActualLength = PP.getSpelling(PeekTok, ThisTokBegin);
+ CharLiteralParser Literal(ThisTokBegin, ThisTokBegin+ActualLength,
+ PeekTok.getLocation(), PP);
+ if (Literal.hadError())
+ return true; // A diagnostic was already emitted.
+
+ // Character literals are always int or wchar_t, expand to intmax_t.
+ TargetInfo &TI = PP.getTargetInfo();
+ unsigned NumBits;
+ if (Literal.isWide())
+ NumBits = TI.getWCharWidth(PeekTok.getLocation());
+ else
+ NumBits = TI.getCharWidth(PeekTok.getLocation());
+
+ // Set the width.
+ llvm::APSInt Val(NumBits);
+ // Set the value.
+ Val = Literal.getValue();
+ // Set the signedness.
+ Val.setIsUnsigned(!TI.isCharSigned(PeekTok.getLocation()));
+
+ if (Result.getBitWidth() > Val.getBitWidth()) {
+ if (Val.isSigned())
+ Result = Val.sext(Result.getBitWidth());
+ else
+ Result = Val.zext(Result.getBitWidth());
+ Result.setIsUnsigned(Val.isUnsigned());
+ } else {
+ assert(Result.getBitWidth() == Val.getBitWidth() &&
+ "intmax_t smaller than char/wchar_t?");
+ Result = Val;
+ }
+
+ // Consume the token.
+ PP.LexNonComment(PeekTok);
+ return false;
+ }
+ case tok::l_paren:
+ PP.LexNonComment(PeekTok); // Eat the (.
+ // Parse the value and if there are any binary operators involved, parse
+ // them.
+ if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
+
+ // If this is a silly value like (X), which doesn't need parens, check for
+ // !(defined X).
+ if (PeekTok.getKind() == tok::r_paren) {
+ // Just use DT unmodified as our result.
+ } else {
+ if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive, PP))
+ return true;
+
+ if (PeekTok.getKind() != tok::r_paren) {
+ PP.Diag(PeekTok, diag::err_pp_expected_rparen);
+ return true;
+ }
+ DT.State = DefinedTracker::Unknown;
+ }
+ PP.LexNonComment(PeekTok); // Eat the ).
+ return false;
+
+ case tok::plus:
+ // Unary plus doesn't modify the value.
+ PP.LexNonComment(PeekTok);
+ return EvaluateValue(Result, PeekTok, DT, ValueLive, PP);
+ case tok::minus: {
+ SourceLocation Loc = PeekTok.getLocation();
+ PP.LexNonComment(PeekTok);
+ if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
+ // C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
+ Result = -Result;
+
+ bool Overflow = false;
+ if (Result.isUnsigned())
+ Overflow = !Result.isPositive();
+ else if (Result.isMinSignedValue())
+ Overflow = true; // -MININT is the only thing that overflows.
+
+ // If this operator is live and overflowed, report the issue.
+ if (Overflow && ValueLive)
+ PP.Diag(Loc, diag::warn_pp_expr_overflow);
+
+ DT.State = DefinedTracker::Unknown;
+ return false;
+ }
+
+ case tok::tilde:
+ PP.LexNonComment(PeekTok);
+ if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
+ // C99 6.5.3.3p4: The sign of the result matches the sign of the operand.
+ Result = ~Result;
+ DT.State = DefinedTracker::Unknown;
+ return false;
+
+ case tok::exclaim:
+ PP.LexNonComment(PeekTok);
+ if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
+ Result = !Result;
+ // C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed.
+ Result.setIsUnsigned(false);
+
+ if (DT.State == DefinedTracker::DefinedMacro)
+ DT.State = DefinedTracker::NotDefinedMacro;
+ else if (DT.State == DefinedTracker::NotDefinedMacro)
+ DT.State = DefinedTracker::DefinedMacro;
+ return false;
+
+ // FIXME: Handle #assert
+ }
+}
+
+
+
+/// getPrecedence - Return the precedence of the specified binary operator
+/// token. This returns:
+/// ~0 - Invalid token.
+/// 14 - *,/,%
+/// 13 - -,+
+/// 12 - <<,>>
+/// 11 - >=, <=, >, <
+/// 10 - ==, !=
+/// 9 - &
+/// 8 - ^
+/// 7 - |
+/// 6 - &&
+/// 5 - ||
+/// 4 - ?
+/// 3 - :
+/// 0 - eom, )
+static unsigned getPrecedence(tok::TokenKind Kind) {
+ switch (Kind) {
+ default: return ~0U;
+ case tok::percent:
+ case tok::slash:
+ case tok::star: return 14;
+ case tok::plus:
+ case tok::minus: return 13;
+ case tok::lessless:
+ case tok::greatergreater: return 12;
+ case tok::lessequal:
+ case tok::less:
+ case tok::greaterequal:
+ case tok::greater: return 11;
+ case tok::exclaimequal:
+ case tok::equalequal: return 10;
+ case tok::amp: return 9;
+ case tok::caret: return 8;
+ case tok::pipe: return 7;
+ case tok::ampamp: return 6;
+ case tok::pipepipe: return 5;
+ case tok::question: return 4;
+ case tok::colon: return 3;
+ case tok::comma: return 2;
+ case tok::r_paren: return 0; // Lowest priority, end of expr.
+ case tok::eom: return 0; // Lowest priority, end of macro.
+ }
+}
+
+
+/// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is
+/// PeekTok, and whose precedence is PeekPrec.
+///
+/// If ValueLive is false, then this value is being evaluated in a context where
+/// the result is not used. As such, avoid diagnostics that relate to
+/// evaluation.
+static bool EvaluateDirectiveSubExpr(llvm::APSInt &LHS, unsigned MinPrec,
+ LexerToken &PeekTok, bool ValueLive,
+ Preprocessor &PP) {
+ unsigned PeekPrec = getPrecedence(PeekTok.getKind());
+ // If this token isn't valid, report the error.
+ if (PeekPrec == ~0U) {
+ PP.Diag(PeekTok, diag::err_pp_expr_bad_token);
+ return true;
+ }
+
+ while (1) {
+ // If this token has a lower precedence than we are allowed to parse, return
+ // it so that higher levels of the recursion can parse it.
+ if (PeekPrec < MinPrec)
+ return false;
+
+ tok::TokenKind Operator = PeekTok.getKind();
+
+ // If this is a short-circuiting operator, see if the RHS of the operator is
+ // dead. Note that this cannot just clobber ValueLive. Consider
+ // "0 && 1 ? 4 : 1 / 0", which is parsed as "(0 && 1) ? 4 : (1 / 0)". In
+ // this example, the RHS of the && being dead does not make the rest of the
+ // expr dead.
+ bool RHSIsLive;
+ if (Operator == tok::ampamp && LHS == 0)
+ RHSIsLive = false; // RHS of "0 && x" is dead.
+ else if (Operator == tok::pipepipe && LHS != 0)
+ RHSIsLive = false; // RHS of "1 || x" is dead.
+ else if (Operator == tok::question && LHS == 0)
+ RHSIsLive = false; // RHS (x) of "0 ? x : y" is dead.
+ else
+ RHSIsLive = ValueLive;
+
+ // Consume the operator, saving the operator token for error reporting.
+ LexerToken OpToken = PeekTok;
+ PP.LexNonComment(PeekTok);
+
+ llvm::APSInt RHS(LHS.getBitWidth());
+ // Parse the RHS of the operator.
+ DefinedTracker DT;
+ if (EvaluateValue(RHS, PeekTok, DT, RHSIsLive, PP)) return true;
+
+ // Remember the precedence of this operator and get the precedence of the
+ // operator immediately to the right of the RHS.
+ unsigned ThisPrec = PeekPrec;
+ PeekPrec = getPrecedence(PeekTok.getKind());
+
+ // If this token isn't valid, report the error.
+ if (PeekPrec == ~0U) {
+ PP.Diag(PeekTok, diag::err_pp_expr_bad_token);
+ return true;
+ }
+
+ bool isRightAssoc = Operator == tok::question;
+
+ // Get the precedence of the operator to the right of the RHS. If it binds
+ // more tightly with RHS than we do, evaluate it completely first.
+ if (ThisPrec < PeekPrec ||
+ (ThisPrec == PeekPrec && isRightAssoc)) {
+ if (EvaluateDirectiveSubExpr(RHS, ThisPrec+1, PeekTok, RHSIsLive, PP))
+ return true;
+ PeekPrec = getPrecedence(PeekTok.getKind());
+ }
+ assert(PeekPrec <= ThisPrec && "Recursion didn't work!");
+
+ // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
+ // either operand is unsigned. Don't do this for x and y in "x ? y : z".
+ llvm::APSInt Res(LHS.getBitWidth());
+ if (Operator != tok::question) {
+ Res.setIsUnsigned(LHS.isUnsigned()|RHS.isUnsigned());
+ // If this just promoted something from signed to unsigned, and if the
+ // value was negative, warn about it.
+ if (ValueLive && Res.isUnsigned()) {
+ if (!LHS.isUnsigned() && LHS.isNegative())
+ PP.Diag(OpToken, diag::warn_pp_convert_lhs_to_positive,
+ LHS.toString(10, true) + " to " + LHS.toString(10, false));
+ if (!RHS.isUnsigned() && RHS.isNegative())
+ PP.Diag(OpToken, diag::warn_pp_convert_rhs_to_positive,
+ RHS.toString(10, true) + " to " + RHS.toString(10, false));
+ }
+ LHS.setIsUnsigned(Res.isUnsigned());
+ RHS.setIsUnsigned(Res.isUnsigned());
+ }
+
+ // FIXME: All of these should detect and report overflow??
+ bool Overflow = false;
+ switch (Operator) {
+ default: assert(0 && "Unknown operator token!");
+ case tok::percent:
+ if (RHS == 0) {
+ if (ValueLive) PP.Diag(OpToken, diag::err_pp_remainder_by_zero);
+ return true;
+ }
+ Res = LHS % RHS;
+ break;
+ case tok::slash:
+ if (RHS == 0) {
+ if (ValueLive) PP.Diag(OpToken, diag::err_pp_division_by_zero);
+ return true;
+ }
+ Res = LHS / RHS;
+ if (LHS.isSigned())
+ Overflow = LHS.isMinSignedValue() && RHS.isAllOnesValue(); // MININT/-1
+ break;
+ case tok::star:
+ Res = LHS * RHS;
+ if (LHS != 0 && RHS != 0)
+ Overflow = Res/RHS != LHS || Res/LHS != RHS;
+ break;
+ case tok::lessless: {
+ // Determine whether overflow is about to happen.
+ unsigned ShAmt = RHS.getLimitedValue();
+ if (ShAmt >= LHS.getBitWidth())
+ Overflow = true, ShAmt = LHS.getBitWidth()-1;
+ else if (LHS.isUnsigned())
+ Overflow = ShAmt > LHS.countLeadingZeros();
+ else if (LHS.isPositive())
+ Overflow = ShAmt >= LHS.countLeadingZeros(); // Don't allow sign change.
+ else
+ Overflow = ShAmt >= LHS.countLeadingOnes();
+
+ Res = LHS << ShAmt;
+ break;
+ }
+ case tok::greatergreater: {
+ // Determine whether overflow is about to happen.
+ unsigned ShAmt = RHS.getLimitedValue();
+ if (ShAmt >= LHS.getBitWidth())
+ Overflow = true, ShAmt = LHS.getBitWidth()-1;
+ Res = LHS >> ShAmt;
+ break;
+ }
+ case tok::plus:
+ Res = LHS + RHS;
+ if (LHS.isUnsigned())
+ Overflow = Res.ult(LHS);
+ else if (LHS.isPositive() == RHS.isPositive() &&
+ Res.isPositive() != LHS.isPositive())
+ Overflow = true; // Overflow for signed addition.
+ break;
+ case tok::minus:
+ Res = LHS - RHS;
+ if (LHS.isUnsigned())
+ Overflow = Res.ugt(LHS);
+ else if (LHS.isPositive() != RHS.isPositive() &&
+ Res.isPositive() != LHS.isPositive())
+ Overflow = true; // Overflow for signed subtraction.
+ break;
+ case tok::lessequal:
+ Res = LHS <= RHS;
+ Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
+ break;
+ case tok::less:
+ Res = LHS < RHS;
+ Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
+ break;
+ case tok::greaterequal:
+ Res = LHS >= RHS;
+ Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
+ break;
+ case tok::greater:
+ Res = LHS > RHS;
+ Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
+ break;
+ case tok::exclaimequal:
+ Res = LHS != RHS;
+ Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
+ break;
+ case tok::equalequal:
+ Res = LHS == RHS;
+ Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
+ break;
+ case tok::amp:
+ Res = LHS & RHS;
+ break;
+ case tok::caret:
+ Res = LHS ^ RHS;
+ break;
+ case tok::pipe:
+ Res = LHS | RHS;
+ break;
+ case tok::ampamp:
+ Res = (LHS != 0 && RHS != 0);
+ Res.setIsUnsigned(false); // C99 6.5.13p3, result is always int (signed)
+ break;
+ case tok::pipepipe:
+ Res = (LHS != 0 || RHS != 0);
+ Res.setIsUnsigned(false); // C99 6.5.14p3, result is always int (signed)
+ break;
+ case tok::comma:
+ PP.Diag(OpToken, diag::ext_pp_comma_expr);
+ Res = RHS; // LHS = LHS,RHS -> RHS.
+ break;
+ case tok::question: {
+ // Parse the : part of the expression.
+ if (PeekTok.getKind() != tok::colon) {
+ PP.Diag(OpToken, diag::err_pp_question_without_colon);
+ return true;
+ }
+ // Consume the :.
+ PP.LexNonComment(PeekTok);
+
+ // Evaluate the value after the :.
+ bool AfterColonLive = ValueLive && LHS == 0;
+ llvm::APSInt AfterColonVal(LHS.getBitWidth());
+ DefinedTracker DT;
+ if (EvaluateValue(AfterColonVal, PeekTok, DT, AfterColonLive, PP))
+ return true;
+
+ // Parse anything after the : RHS that has a higher precedence than ?.
+ if (EvaluateDirectiveSubExpr(AfterColonVal, ThisPrec+1,
+ PeekTok, AfterColonLive, PP))
+ return true;
+
+ // Now that we have the condition, the LHS and the RHS of the :, evaluate.
+ Res = LHS != 0 ? RHS : AfterColonVal;
+
+ // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if
+ // either operand is unsigned.
+ Res.setIsUnsigned(RHS.isUnsigned() | AfterColonVal.isUnsigned());
+
+ // Figure out the precedence of the token after the : part.
+ PeekPrec = getPrecedence(PeekTok.getKind());
+ break;
+ }
+ case tok::colon:
+ // Don't allow :'s to float around without being part of ?: exprs.
+ PP.Diag(OpToken, diag::err_pp_colon_without_question);
+ return true;
+ }
+
+ // If this operator is live and overflowed, report the issue.
+ if (Overflow && ValueLive)
+ PP.Diag(OpToken, diag::warn_pp_expr_overflow);
+
+ // Put the result back into 'LHS' for our next iteration.
+ LHS = Res;
+ }
+
+ return false;
+}
+
+/// EvaluateDirectiveExpression - Evaluate an integer constant expression that
+/// may occur after a #if or #elif directive. If the expression is equivalent
+/// to "!defined(X)" return X in IfNDefMacro.
+bool Preprocessor::
+EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro) {
+ // Peek ahead one token.
+ LexerToken Tok;
+ Lex(Tok);
+
+ // C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
+ unsigned BitWidth = getTargetInfo().getIntMaxTWidth(Tok.getLocation());
+ llvm::APSInt ResVal(BitWidth);
+ DefinedTracker DT;
+ if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
+ // Parse error, skip the rest of the macro line.
+ if (Tok.getKind() != tok::eom)
+ DiscardUntilEndOfDirective();
+ return false;
+ }
+
+ // If we are at the end of the expression after just parsing a value, there
+ // must be no (unparenthesized) binary operators involved, so we can exit
+ // directly.
+ if (Tok.getKind() == tok::eom) {
+ // If the expression we parsed was of the form !defined(macro), return the
+ // macro in IfNDefMacro.
+ if (DT.State == DefinedTracker::NotDefinedMacro)
+ IfNDefMacro = DT.TheMacro;
+
+ return ResVal != 0;
+ }
+
+ // Otherwise, we must have a binary operator (e.g. "#if 1 < 2"), so parse the
+ // operator and the stuff after it.
+ if (EvaluateDirectiveSubExpr(ResVal, 1, Tok, true, *this)) {
+ // Parse error, skip the rest of the macro line.
+ if (Tok.getKind() != tok::eom)
+ DiscardUntilEndOfDirective();
+ return false;
+ }
+
+ // If we aren't at the tok::eom token, something bad happened, like an extra
+ // ')' token.
+ if (Tok.getKind() != tok::eom) {
+ Diag(Tok, diag::err_pp_expected_eol);
+ DiscardUntilEndOfDirective();
+ }
+
+ return ResVal != 0;
+}
+