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llvm-project/clang/lib/Lex/PPExpressions.cpp

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//===--- PPExpressions.cpp - Preprocessor Expression Evaluation -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file 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/Basic/TargetInfo.h"
#include "clang/Lex/CodeCompletionHandler.h"
#include "clang/Lex/LexDiagnostic.h"
#include "clang/Lex/LiteralSupport.h"
#include "clang/Lex/MacroInfo.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SaveAndRestore.h"
using namespace clang;
namespace {
/// PPValue - Represents the value of a subexpression of a preprocessor
/// conditional and the source range covered by it.
class PPValue {
SourceRange Range;
public:
llvm::APSInt Val;
// Default ctor - Construct an 'invalid' PPValue.
PPValue(unsigned BitWidth) : Val(BitWidth) {}
unsigned getBitWidth() const { return Val.getBitWidth(); }
bool isUnsigned() const { return Val.isUnsigned(); }
const SourceRange &getRange() const { return Range; }
void setRange(SourceLocation L) { Range.setBegin(L); Range.setEnd(L); }
void setRange(SourceLocation B, SourceLocation E) {
Range.setBegin(B); Range.setEnd(E);
}
void setBegin(SourceLocation L) { Range.setBegin(L); }
void setEnd(SourceLocation L) { Range.setEnd(L); }
};
}
static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
Token &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;
};
/// EvaluateDefined - Process a 'defined(sym)' expression.
static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
bool ValueLive, Preprocessor &PP) {
IdentifierInfo *II;
Result.setBegin(PeekTok.getLocation());
// Get the next token, don't expand it.
PP.LexUnexpandedNonComment(PeekTok);
// Two options, it can either be a pp-identifier or a (.
SourceLocation LParenLoc;
if (PeekTok.is(tok::l_paren)) {
// Found a paren, remember we saw it and skip it.
LParenLoc = PeekTok.getLocation();
PP.LexUnexpandedNonComment(PeekTok);
}
if (PeekTok.is(tok::code_completion)) {
if (PP.getCodeCompletionHandler())
PP.getCodeCompletionHandler()->CodeCompleteMacroName(false);
PP.setCodeCompletionReached();
PP.LexUnexpandedNonComment(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.Val = II->hasMacroDefinition();
Result.Val.setIsUnsigned(false); // Result is signed intmax_t.
MacroDirective *Macro = 0;
// If there is a macro, mark it used.
if (Result.Val != 0 && ValueLive) {
Macro = PP.getMacroDirective(II);
PP.markMacroAsUsed(Macro->getMacroInfo());
}
// Invoke the 'defined' callback.
if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
MacroDirective *MD = Macro;
// Pass the MacroInfo for the macro name even if the value is dead.
if (!MD && Result.Val != 0)
MD = PP.getMacroDirective(II);
Callbacks->Defined(PeekTok, MD);
}
// If we are in parens, ensure we have a trailing ).
if (LParenLoc.isValid()) {
// Consume identifier.
Result.setEnd(PeekTok.getLocation());
PP.LexUnexpandedNonComment(PeekTok);
if (PeekTok.isNot(tok::r_paren)) {
PP.Diag(PeekTok.getLocation(), diag::err_pp_missing_rparen) << "defined";
PP.Diag(LParenLoc, diag::note_matching) << "(";
return true;
}
// Consume the ).
Result.setEnd(PeekTok.getLocation());
PP.LexNonComment(PeekTok);
} else {
// Consume identifier.
Result.setEnd(PeekTok.getLocation());
PP.LexNonComment(PeekTok);
}
// Success, remember that we saw defined(X).
DT.State = DefinedTracker::DefinedMacro;
DT.TheMacro = II;
return false;
}
/// 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(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
bool ValueLive, Preprocessor &PP) {
DT.State = DefinedTracker::Unknown;
if (PeekTok.is(tok::code_completion)) {
if (PP.getCodeCompletionHandler())
PP.getCodeCompletionHandler()->CodeCompletePreprocessorExpression();
PP.setCodeCompletionReached();
PP.LexNonComment(PeekTok);
}
// 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()) {
// Handle "defined X" and "defined(X)".
if (II->isStr("defined"))
return(EvaluateDefined(Result, PeekTok, DT, ValueLive, PP));
// If this identifier isn't 'defined' or one of the special
// preprocessor keywords 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 (ValueLive &&
II->getTokenID() != tok::kw_true &&
II->getTokenID() != tok::kw_false)
PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II;
Result.Val = II->getTokenID() == tok::kw_true;
Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0.
Result.setRange(PeekTok.getLocation());
PP.LexNonComment(PeekTok);
return false;
}
switch (PeekTok.getKind()) {
default: // Non-value token.
PP.Diag(PeekTok, diag::err_pp_expr_bad_token_start_expr);
return true;
case tok::eod:
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: {
SmallString<64> IntegerBuffer;
bool NumberInvalid = false;
StringRef Spelling = PP.getSpelling(PeekTok, IntegerBuffer,
&NumberInvalid);
if (NumberInvalid)
return true; // a diagnostic was already reported
NumericLiteralParser Literal(Spelling, PeekTok.getLocation(), PP);
if (Literal.hadError)
return true; // a diagnostic was already reported.
if (Literal.isFloatingLiteral() || Literal.isImaginary) {
PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
return true;
}
assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
// Complain about, and drop, any ud-suffix.
if (Literal.hasUDSuffix())
PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*integer*/1;
// 'long long' is a C99 or C++11 feature.
if (!PP.getLangOpts().C99 && Literal.isLongLong) {
if (PP.getLangOpts().CPlusPlus)
PP.Diag(PeekTok,
PP.getLangOpts().CPlusPlus11 ?
diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
else
PP.Diag(PeekTok, diag::ext_c99_longlong);
}
// Parse the integer literal into Result.
if (Literal.GetIntegerValue(Result.Val)) {
// Overflow parsing integer literal.
if (ValueLive) PP.Diag(PeekTok, diag::warn_integer_too_large);
Result.Val.setIsUnsigned(true);
} else {
// Set the signedness of the result to match whether there was a U suffix
// or not.
Result.Val.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.Val.isNegative()) {
// Don't warn for a hex literal: 0x8000..0 shouldn't warn.
if (ValueLive && Literal.getRadix() != 16)
PP.Diag(PeekTok, diag::warn_integer_too_large_for_signed);
Result.Val.setIsUnsigned(true);
}
}
// Consume the token.
Result.setRange(PeekTok.getLocation());
PP.LexNonComment(PeekTok);
return false;
}
case tok::char_constant: // 'x'
case tok::wide_char_constant: // L'x'
case tok::utf16_char_constant: // u'x'
case tok::utf32_char_constant: { // U'x'
// Complain about, and drop, any ud-suffix.
if (PeekTok.hasUDSuffix())
PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*character*/0;
SmallString<32> CharBuffer;
bool CharInvalid = false;
StringRef ThisTok = PP.getSpelling(PeekTok, CharBuffer, &CharInvalid);
if (CharInvalid)
return true;
CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(),
PeekTok.getLocation(), PP, PeekTok.getKind());
if (Literal.hadError())
return true; // A diagnostic was already emitted.
// Character literals are always int or wchar_t, expand to intmax_t.
const TargetInfo &TI = PP.getTargetInfo();
unsigned NumBits;
if (Literal.isMultiChar())
NumBits = TI.getIntWidth();
else if (Literal.isWide())
NumBits = TI.getWCharWidth();
else if (Literal.isUTF16())
NumBits = TI.getChar16Width();
else if (Literal.isUTF32())
NumBits = TI.getChar32Width();
else
NumBits = TI.getCharWidth();
// Set the width.
llvm::APSInt Val(NumBits);
// Set the value.
Val = Literal.getValue();
// Set the signedness. UTF-16 and UTF-32 are always unsigned
if (!Literal.isUTF16() && !Literal.isUTF32())
Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned);
if (Result.Val.getBitWidth() > Val.getBitWidth()) {
Result.Val = Val.extend(Result.Val.getBitWidth());
} else {
assert(Result.Val.getBitWidth() == Val.getBitWidth() &&
"intmax_t smaller than char/wchar_t?");
Result.Val = Val;
}
// Consume the token.
Result.setRange(PeekTok.getLocation());
PP.LexNonComment(PeekTok);
return false;
}
case tok::l_paren: {
SourceLocation Start = PeekTok.getLocation();
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.is(tok::r_paren)) {
// Just use DT unmodified as our result.
} else {
// Otherwise, we have something like (x+y), and we consumed '(x'.
if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive, PP))
return true;
if (PeekTok.isNot(tok::r_paren)) {
PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_rparen)
<< Result.getRange();
PP.Diag(Start, diag::note_matching) << "(";
return true;
}
DT.State = DefinedTracker::Unknown;
}
Result.setRange(Start, PeekTok.getLocation());
PP.LexNonComment(PeekTok); // Eat the ).
return false;
}
case tok::plus: {
SourceLocation Start = PeekTok.getLocation();
// Unary plus doesn't modify the value.
PP.LexNonComment(PeekTok);
if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
Result.setBegin(Start);
return false;
}
case tok::minus: {
SourceLocation Loc = PeekTok.getLocation();
PP.LexNonComment(PeekTok);
if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
Result.setBegin(Loc);
// C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
Result.Val = -Result.Val;
// -MININT is the only thing that overflows. Unsigned never overflows.
bool Overflow = !Result.isUnsigned() && Result.Val.isMinSignedValue();
// If this operator is live and overflowed, report the issue.
if (Overflow && ValueLive)
PP.Diag(Loc, diag::warn_pp_expr_overflow) << Result.getRange();
DT.State = DefinedTracker::Unknown;
return false;
}
case tok::tilde: {
SourceLocation Start = PeekTok.getLocation();
PP.LexNonComment(PeekTok);
if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
Result.setBegin(Start);
// C99 6.5.3.3p4: The sign of the result matches the sign of the operand.
Result.Val = ~Result.Val;
DT.State = DefinedTracker::Unknown;
return false;
}
case tok::exclaim: {
SourceLocation Start = PeekTok.getLocation();
PP.LexNonComment(PeekTok);
if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
Result.setBegin(Start);
Result.Val = !Result.Val;
// C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed.
Result.Val.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 -> 3 - various operators.
/// 0 - 'eod' or ')'
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::comma: return 3;
case tok::colon: return 2;
case tok::r_paren: return 0;// Lowest priority, end of expr.
case tok::eod: return 0;// Lowest priority, end of directive.
}
}
/// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is
/// PeekTok, and whose precedence is PeekPrec. This returns the result in LHS.
///
/// 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, such as division by zero warnings.
static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec,
Token &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.getLocation(), diag::err_pp_expr_bad_token_binop)
<< LHS.getRange();
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.Val == 0)
RHSIsLive = false; // RHS of "0 && x" is dead.
else if (Operator == tok::pipepipe && LHS.Val != 0)
RHSIsLive = false; // RHS of "1 || x" is dead.
else if (Operator == tok::question && LHS.Val == 0)
RHSIsLive = false; // RHS (x) of "0 ? x : y" is dead.
else
RHSIsLive = ValueLive;
// Consume the operator, remembering the operator's location for reporting.
SourceLocation OpLoc = PeekTok.getLocation();
PP.LexNonComment(PeekTok);
PPValue 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.getLocation(), diag::err_pp_expr_bad_token_binop)
<< RHS.getRange();
return true;
}
// Decide whether to include the next binop in this subexpression. For
// example, when parsing x+y*z and looking at '*', we want to recursively
// handle y*z as a single subexpression. We do this because the precedence
// of * is higher than that of +. The only strange case we have to handle
// here is for the ?: operator, where the precedence is actually lower than
// the LHS of the '?'. The grammar rule is:
//
// conditional-expression ::=
// logical-OR-expression ? expression : conditional-expression
// where 'expression' is actually comma-expression.
unsigned RHSPrec;
if (Operator == tok::question)
// The RHS of "?" should be maximally consumed as an expression.
RHSPrec = getPrecedence(tok::comma);
else // All others should munch while higher precedence.
RHSPrec = ThisPrec+1;
if (PeekPrec >= RHSPrec) {
if (EvaluateDirectiveSubExpr(RHS, RHSPrec, 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.
llvm::APSInt Res(LHS.getBitWidth());
switch (Operator) {
case tok::question: // No UAC for x and y in "x ? y : z".
case tok::lessless: // Shift amount doesn't UAC with shift value.
case tok::greatergreater: // Shift amount doesn't UAC with shift value.
case tok::comma: // Comma operands are not subject to UACs.
case tok::pipepipe: // Logical || does not do UACs.
case tok::ampamp: // Logical && does not do UACs.
break; // No UAC
default:
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.Val.isNegative())
PP.Diag(OpLoc, diag::warn_pp_convert_lhs_to_positive)
<< LHS.Val.toString(10, true) + " to " +
LHS.Val.toString(10, false)
<< LHS.getRange() << RHS.getRange();
if (!RHS.isUnsigned() && RHS.Val.isNegative())
PP.Diag(OpLoc, diag::warn_pp_convert_rhs_to_positive)
<< RHS.Val.toString(10, true) + " to " +
RHS.Val.toString(10, false)
<< LHS.getRange() << RHS.getRange();
}
LHS.Val.setIsUnsigned(Res.isUnsigned());
RHS.Val.setIsUnsigned(Res.isUnsigned());
}
bool Overflow = false;
switch (Operator) {
default: llvm_unreachable("Unknown operator token!");
case tok::percent:
if (RHS.Val != 0)
Res = LHS.Val % RHS.Val;
else if (ValueLive) {
PP.Diag(OpLoc, diag::err_pp_remainder_by_zero)
<< LHS.getRange() << RHS.getRange();
return true;
}
break;
case tok::slash:
if (RHS.Val != 0) {
if (LHS.Val.isSigned())
Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS.Val, Overflow), false);
else
Res = LHS.Val / RHS.Val;
} else if (ValueLive) {
PP.Diag(OpLoc, diag::err_pp_division_by_zero)
<< LHS.getRange() << RHS.getRange();
return true;
}
break;
case tok::star:
if (Res.isSigned())
Res = llvm::APSInt(LHS.Val.smul_ov(RHS.Val, Overflow), false);
else
Res = LHS.Val * RHS.Val;
break;
case tok::lessless: {
// Determine whether overflow is about to happen.
unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
if (LHS.isUnsigned()) {
Overflow = ShAmt >= LHS.Val.getBitWidth();
if (Overflow)
ShAmt = LHS.Val.getBitWidth()-1;
Res = LHS.Val << ShAmt;
} else {
Res = llvm::APSInt(LHS.Val.sshl_ov(ShAmt, Overflow), false);
}
break;
}
case tok::greatergreater: {
// Determine whether overflow is about to happen.
unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue());
if (ShAmt >= LHS.getBitWidth())
Overflow = true, ShAmt = LHS.getBitWidth()-1;
Res = LHS.Val >> ShAmt;
break;
}
case tok::plus:
if (LHS.isUnsigned())
Res = LHS.Val + RHS.Val;
else
Res = llvm::APSInt(LHS.Val.sadd_ov(RHS.Val, Overflow), false);
break;
case tok::minus:
if (LHS.isUnsigned())
Res = LHS.Val - RHS.Val;
else
Res = llvm::APSInt(LHS.Val.ssub_ov(RHS.Val, Overflow), false);
break;
case tok::lessequal:
Res = LHS.Val <= RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
break;
case tok::less:
Res = LHS.Val < RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
break;
case tok::greaterequal:
Res = LHS.Val >= RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
break;
case tok::greater:
Res = LHS.Val > RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed)
break;
case tok::exclaimequal:
Res = LHS.Val != RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
break;
case tok::equalequal:
Res = LHS.Val == RHS.Val;
Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed)
break;
case tok::amp:
Res = LHS.Val & RHS.Val;
break;
case tok::caret:
Res = LHS.Val ^ RHS.Val;
break;
case tok::pipe:
Res = LHS.Val | RHS.Val;
break;
case tok::ampamp:
Res = (LHS.Val != 0 && RHS.Val != 0);
Res.setIsUnsigned(false); // C99 6.5.13p3, result is always int (signed)
break;
case tok::pipepipe:
Res = (LHS.Val != 0 || RHS.Val != 0);
Res.setIsUnsigned(false); // C99 6.5.14p3, result is always int (signed)
break;
case tok::comma:
// Comma is invalid in pp expressions in c89/c++ mode, but is valid in C99
// if not being evaluated.
if (!PP.getLangOpts().C99 || ValueLive)
PP.Diag(OpLoc, diag::ext_pp_comma_expr)
<< LHS.getRange() << RHS.getRange();
Res = RHS.Val; // LHS = LHS,RHS -> RHS.
break;
case tok::question: {
// Parse the : part of the expression.
if (PeekTok.isNot(tok::colon)) {
PP.Diag(PeekTok.getLocation(), diag::err_expected_colon)
<< LHS.getRange(), RHS.getRange();
PP.Diag(OpLoc, diag::note_matching) << "?";
return true;
}
// Consume the :.
PP.LexNonComment(PeekTok);
// Evaluate the value after the :.
bool AfterColonLive = ValueLive && LHS.Val == 0;
PPValue AfterColonVal(LHS.getBitWidth());
DefinedTracker DT;
if (EvaluateValue(AfterColonVal, PeekTok, DT, AfterColonLive, PP))
return true;
// Parse anything after the : with the same precedence as ?. We allow
// things of equal precedence because ?: is right associative.
if (EvaluateDirectiveSubExpr(AfterColonVal, ThisPrec,
PeekTok, AfterColonLive, PP))
return true;
// Now that we have the condition, the LHS and the RHS of the :, evaluate.
Res = LHS.Val != 0 ? RHS.Val : AfterColonVal.Val;
RHS.setEnd(AfterColonVal.getRange().getEnd());
// 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(OpLoc, diag::err_pp_colon_without_question)
<< LHS.getRange() << RHS.getRange();
return true;
}
// If this operator is live and overflowed, report the issue.
if (Overflow && ValueLive)
PP.Diag(OpLoc, diag::warn_pp_expr_overflow)
<< LHS.getRange() << RHS.getRange();
// Put the result back into 'LHS' for our next iteration.
LHS.Val = Res;
LHS.setEnd(RHS.getRange().getEnd());
}
}
/// 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) {
SaveAndRestore<bool> PPDir(ParsingIfOrElifDirective, true);
// Save the current state of 'DisableMacroExpansion' and reset it to false. If
// 'DisableMacroExpansion' is true, then we must be in a macro argument list
// in which case a directive is undefined behavior. We want macros to be able
// to recursively expand in order to get more gcc-list behavior, so we force
// DisableMacroExpansion to false and restore it when we're done parsing the
// expression.
bool DisableMacroExpansionAtStartOfDirective = DisableMacroExpansion;
DisableMacroExpansion = false;
// Peek ahead one token.
Token Tok;
LexNonComment(Tok);
// C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
unsigned BitWidth = getTargetInfo().getIntMaxTWidth();
PPValue ResVal(BitWidth);
DefinedTracker DT;
if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
// Parse error, skip the rest of the macro line.
if (Tok.isNot(tok::eod))
DiscardUntilEndOfDirective();
// Restore 'DisableMacroExpansion'.
DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
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.is(tok::eod)) {
// If the expression we parsed was of the form !defined(macro), return the
// macro in IfNDefMacro.
if (DT.State == DefinedTracker::NotDefinedMacro)
IfNDefMacro = DT.TheMacro;
// Restore 'DisableMacroExpansion'.
DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
return ResVal.Val != 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, getPrecedence(tok::question),
Tok, true, *this)) {
// Parse error, skip the rest of the macro line.
if (Tok.isNot(tok::eod))
DiscardUntilEndOfDirective();
// Restore 'DisableMacroExpansion'.
DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
return false;
}
// If we aren't at the tok::eod token, something bad happened, like an extra
// ')' token.
if (Tok.isNot(tok::eod)) {
Diag(Tok, diag::err_pp_expected_eol);
DiscardUntilEndOfDirective();
}
// Restore 'DisableMacroExpansion'.
DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective;
return ResVal.Val != 0;
}
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