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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/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,
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;
};
/// 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, Token &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) {
PP.Diag(PeekTok, diag::warn_pp_undef_identifier, II->getName());
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.is(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->hasMacroDefinition();
Result.setIsUnsigned(false); // Result is signed intmax_t.
// If there is a macro, mark it used.
if (Result != 0 && ValueLive) {
MacroInfo *Macro = PP.getMacroInfo(II);
Macro->setIsUsed(true);
}
// Consume identifier.
PP.LexNonComment(PeekTok);
// If we are in parens, ensure we have a trailing ).
if (InParens) {
if (PeekTok.isNot(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_start_expr);
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() || Literal.isImaginary) {
PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
return true;
}
assert(Literal.isIntegerLiteral() && "Unknown ppnumber");
// long long is a C99 feature.
if (!PP.getLangOptions().C99 && !PP.getLangOptions().CPlusPlus0x
&& Literal.isLongLong)
PP.Diag(PeekTok, diag::ext_longlong);
// 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 = TI.getCharWidth(Literal.isWide());
// Set the width.
llvm::APSInt Val(NumBits);
// Set the value.
Val = Literal.getValue();
// Set the signedness.
Val.setIsUnsigned(!TI.isCharSigned());
if (Result.getBitWidth() > Val.getBitWidth()) {
Result = Val.extend(Result.getBitWidth());
} 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.is(tok::r_paren)) {
// Just use DT unmodified as our result.
} else {
if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive, PP))
return true;
if (PeekTok.isNot(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.isNegative();
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,
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, diag::err_pp_expr_bad_token_binop);
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.
Token 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_binop);
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.toStringSigned() + " to " + LHS.toStringUnsigned());
if (!RHS.isUnsigned() && RHS.isNegative())
PP.Diag(OpToken, diag::warn_pp_convert_rhs_to_positive,
RHS.toStringSigned() + " to " + RHS.toStringUnsigned());
}
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 = static_cast<unsigned>(RHS.getLimitedValue());
if (ShAmt >= LHS.getBitWidth())
Overflow = true, ShAmt = LHS.getBitWidth()-1;
else if (LHS.isUnsigned())
Overflow = ShAmt > LHS.countLeadingZeros();
else if (LHS.isNonNegative())
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 = static_cast<unsigned>(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.isNonNegative() == RHS.isNonNegative() &&
Res.isNonNegative() != LHS.isNonNegative())
Overflow = true; // Overflow for signed addition.
break;
case tok::minus:
Res = LHS - RHS;
if (LHS.isUnsigned())
Overflow = Res.ugt(LHS);
else if (LHS.isNonNegative() != RHS.isNonNegative() &&
Res.isNonNegative() != LHS.isNonNegative())
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.isNot(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.
Token Tok;
Lex(Tok);
// C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t.
unsigned BitWidth = getTargetInfo().getIntMaxTWidth();
llvm::APSInt ResVal(BitWidth);
DefinedTracker DT;
if (EvaluateValue(ResVal, Tok, DT, true, *this)) {
// Parse error, skip the rest of the macro line.
if (Tok.isNot(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.is(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.isNot(tok::eom))
DiscardUntilEndOfDirective();
return false;
}
// If we aren't at the tok::eom token, something bad happened, like an extra
// ')' token.
if (Tok.isNot(tok::eom)) {
Diag(Tok, diag::err_pp_expected_eol);
DiscardUntilEndOfDirective();
}
return ResVal != 0;
}
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