Patch to check for integer overflow. It has been
commented on and approved by Richard Smith.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173377 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 71489cb..881182b 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -384,13 +384,17 @@
/// expression is a potential constant expression? If so, some diagnostics
/// are suppressed.
bool CheckingPotentialConstantExpression;
+
+ bool IntOverflowCheckMode;
- EvalInfo(const ASTContext &C, Expr::EvalStatus &S)
+ EvalInfo(const ASTContext &C, Expr::EvalStatus &S,
+ bool OverflowCheckMode=false)
: Ctx(const_cast<ASTContext&>(C)), EvalStatus(S), CurrentCall(0),
CallStackDepth(0), NextCallIndex(1),
BottomFrame(*this, SourceLocation(), 0, 0, 0),
EvaluatingDecl(0), EvaluatingDeclValue(0), HasActiveDiagnostic(false),
- CheckingPotentialConstantExpression(false) {}
+ CheckingPotentialConstantExpression(false),
+ IntOverflowCheckMode(OverflowCheckMode) {}
void setEvaluatingDecl(const VarDecl *VD, APValue &Value) {
EvaluatingDecl = VD;
@@ -474,6 +478,8 @@
return OptionalDiagnostic();
}
+ bool getIntOverflowCheckMode() { return IntOverflowCheckMode; }
+
/// Diagnose that the evaluation does not produce a C++11 core constant
/// expression.
template<typename LocArg>
@@ -506,8 +512,12 @@
/// Should we continue evaluation as much as possible after encountering a
/// construct which can't be folded?
bool keepEvaluatingAfterFailure() {
- return CheckingPotentialConstantExpression &&
- EvalStatus.Diag && EvalStatus.Diag->empty();
+ // Should return true in IntOverflowCheckMode, so that we check for
+ // overflow even if some subexpressions can't be evaluated as constants.
+ // subexpressions can't be evaluated as constants.
+ return IntOverflowCheckMode ||
+ (CheckingPotentialConstantExpression &&
+ EvalStatus.Diag && EvalStatus.Diag->empty());
}
};
@@ -4418,8 +4428,14 @@
APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
APSInt Result = Value.trunc(LHS.getBitWidth());
- if (Result.extend(BitWidth) != Value)
- HandleOverflow(Info, E, Value, E->getType());
+ if (Result.extend(BitWidth) != Value) {
+ if (Info.getIntOverflowCheckMode())
+ Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
+ diag::warn_integer_constant_overflow)
+ << Result.toString(10) << E->getType();
+ else
+ HandleOverflow(Info, E, Value, E->getType());
+ }
return Result;
}
@@ -6260,26 +6276,39 @@
return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result);
}
+static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
+ const ASTContext &Ctx, bool &IsConst) {
+ // Fast-path evaluations of integer literals, since we sometimes see files
+ // containing vast quantities of these.
+ if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
+ Result.Val = APValue(APSInt(L->getValue(),
+ L->getType()->isUnsignedIntegerType()));
+ IsConst = true;
+ return true;
+ }
+
+ // FIXME: Evaluating values of large array and record types can cause
+ // performance problems. Only do so in C++11 for now.
+ if (Exp->isRValue() && (Exp->getType()->isArrayType() ||
+ Exp->getType()->isRecordType()) &&
+ !Ctx.getLangOpts().CPlusPlus11) {
+ IsConst = false;
+ return true;
+ }
+ return false;
+}
+
+
/// EvaluateAsRValue - Return true if this is a constant which we can fold using
/// any crazy technique (that has nothing to do with language standards) that
/// we want to. If this function returns true, it returns the folded constant
/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
/// will be applied to the result.
bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const {
- // Fast-path evaluations of integer literals, since we sometimes see files
- // containing vast quantities of these.
- if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(this)) {
- Result.Val = APValue(APSInt(L->getValue(),
- L->getType()->isUnsignedIntegerType()));
- return true;
- }
-
- // FIXME: Evaluating values of large array and record types can cause
- // performance problems. Only do so in C++11 for now.
- if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) &&
- !Ctx.getLangOpts().CPlusPlus11)
- return false;
-
+ bool IsConst;
+ if (FastEvaluateAsRValue(this, Result, Ctx, IsConst))
+ return IsConst;
+
EvalInfo Info(Ctx, Result);
return ::EvaluateAsRValue(Info, this, Result.Val);
}
@@ -6376,6 +6405,17 @@
return EvalResult.Val.getInt();
}
+void Expr::EvaluateForOverflow(const ASTContext &Ctx,
+ SmallVectorImpl<PartialDiagnosticAt> *Diags) const {
+ bool IsConst;
+ EvalResult EvalResult;
+ EvalResult.Diag = Diags;
+ if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst)) {
+ EvalInfo Info(Ctx, EvalResult, true);
+ (void)::EvaluateAsRValue(Info, this, EvalResult.Val);
+ }
+}
+
bool Expr::EvalResult::isGlobalLValue() const {
assert(Val.isLValue());
return IsGlobalLValue(Val.getLValueBase());
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 0d8f764..9af16f3 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -5183,6 +5183,18 @@
AnalyzeImplicitConversions(*this, E, CC);
}
+/// Diagnose when expression is an integer constant expression and its evaluation
+/// results in integer overflow
+void Sema::CheckForIntOverflow (Expr *E) {
+ if (const BinaryOperator *BExpr = dyn_cast<BinaryOperator>(E->IgnoreParens())) {
+ unsigned Opc = BExpr->getOpcode();
+ if (Opc != BO_Add && Opc != BO_Sub && Opc != BO_Mul)
+ return;
+ llvm::SmallVector<PartialDiagnosticAt, 4> Diags;
+ E->EvaluateForOverflow(Context, &Diags);
+ }
+}
+
namespace {
/// \brief Visitor for expressions which looks for unsequenced operations on the
/// same object.
@@ -5622,9 +5634,12 @@
}
}
-void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc) {
+void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
+ bool IsConstexpr) {
CheckImplicitConversions(E, CheckLoc);
CheckUnsequencedOperations(E);
+ if (!IsConstexpr && !E->isValueDependent())
+ CheckForIntOverflow(E);
}
void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index ca9610b..538434d 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7045,7 +7045,9 @@
// struct T { S a, b; } t = { Temp(), Temp() }
//
// we should destroy the first Temp before constructing the second.
- ExprResult Result = ActOnFinishFullExpr(Init, VDecl->getLocation());
+ ExprResult Result = ActOnFinishFullExpr(Init, VDecl->getLocation(),
+ false,
+ VDecl->isConstexpr());
if (Result.isInvalid()) {
VDecl->setInvalidDecl();
return;
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 2658a3a..c70041b 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -5469,7 +5469,8 @@
}
ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
- bool DiscardedValue) {
+ bool DiscardedValue,
+ bool IsConstexpr) {
ExprResult FullExpr = Owned(FE);
if (!FullExpr.get())
@@ -5497,7 +5498,7 @@
return ExprError();
}
- CheckCompletedExpr(FullExpr.get(), CC);
+ CheckCompletedExpr(FullExpr.get(), CC, IsConstexpr);
return MaybeCreateExprWithCleanups(FullExpr);
}
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index a2daa18..fd3ee0d 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -338,6 +338,12 @@
// Recover from an error by just forgetting about it.
}
}
+
+ LHSVal = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
+ getLangOpts().CPlusPlus11).take();
+ if (RHSVal)
+ RHSVal = ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
+ getLangOpts().CPlusPlus11).take();
CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
ColonLoc);
@@ -732,14 +738,7 @@
} else {
// We already verified that the expression has a i-c-e value (C99
// 6.8.4.2p3) - get that value now.
- SmallVector<PartialDiagnosticAt, 8> Diags;
- LoVal = Lo->EvaluateKnownConstInt(Context, &Diags);
- if (Diags.size() == 1 &&
- Diags[0].second.getDiagID() == diag::note_constexpr_overflow) {
- Diag(Lo->getLocStart(), diag::warn_case_constant_overflow) <<
- LoVal.toString(10);
- Diag(Diags[0].first, Diags[0].second);
- }
+ LoVal = Lo->EvaluateKnownConstInt(Context);
// If the LHS is not the same type as the condition, insert an implicit
// cast.