Extend the bitfield-truncation warning to initializations.
rdar://problem/8652606
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118773 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 2f3abfc..4fc16f5 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -2608,6 +2608,55 @@
<< lex->getSourceRange() << rex->getSourceRange();
}
+/// Analyzes an attempt to assign the given value to a bitfield.
+///
+/// Returns true if there was something fishy about the attempt.
+bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
+ SourceLocation InitLoc) {
+ assert(Bitfield->isBitField());
+ if (Bitfield->isInvalidDecl())
+ return false;
+
+ Expr *OriginalInit = Init->IgnoreParenImpCasts();
+
+ llvm::APSInt Width(32);
+ Expr::EvalResult InitValue;
+ if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) ||
+ !Init->Evaluate(InitValue, S.Context) ||
+ !InitValue.Val.isInt())
+ return false;
+
+ const llvm::APSInt &Value = InitValue.Val.getInt();
+ unsigned OriginalWidth = Value.getBitWidth();
+ unsigned FieldWidth = Width.getZExtValue();
+
+ if (OriginalWidth <= FieldWidth)
+ return false;
+
+ llvm::APSInt TruncatedValue = Value;
+ TruncatedValue.trunc(FieldWidth);
+
+ // It's fairly common to write values into signed bitfields
+ // that, if sign-extended, would end up becoming a different
+ // value. We don't want to warn about that.
+ if (Value.isSigned() && Value.isNegative())
+ TruncatedValue.sext(OriginalWidth);
+ else
+ TruncatedValue.zext(OriginalWidth);
+
+ if (Value == TruncatedValue)
+ return false;
+
+ std::string PrettyValue = Value.toString(10);
+ std::string PrettyTrunc = TruncatedValue.toString(10);
+
+ S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
+ << PrettyValue << PrettyTrunc << OriginalInit->getType()
+ << Init->getSourceRange();
+
+ return true;
+}
+
/// Analyze the given simple or compound assignment for warning-worthy
/// operations.
void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
@@ -2617,44 +2666,11 @@
// We want to recurse on the RHS as normal unless we're assigning to
// a bitfield.
if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
- assert(Bitfield->isBitField());
-
- Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
-
- llvm::APSInt Width(32);
- Expr::EvalResult RHSValue;
- if (!Bitfield->isInvalidDecl() &&
- Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) &&
- RHS->Evaluate(RHSValue, S.Context) && RHSValue.Val.isInt()) {
- const llvm::APSInt &Value = RHSValue.Val.getInt();
- unsigned OriginalWidth = Value.getBitWidth();
- unsigned FieldWidth = Width.getZExtValue();
-
- if (OriginalWidth > FieldWidth) {
- llvm::APSInt TruncatedValue = Value;
- TruncatedValue.trunc(FieldWidth);
-
- // It's fairly common to write values into signed bitfields
- // that, if sign-extended, would end up becoming a different
- // value. We don't want to warn about that.
- if (Value.isSigned() && Value.isNegative())
- TruncatedValue.sext(OriginalWidth);
- else
- TruncatedValue.zext(OriginalWidth);
-
- if (Value != TruncatedValue) {
- std::string PrettyValue = Value.toString(10);
- std::string PrettyTrunc = TruncatedValue.toString(10);
-
- S.Diag(E->getOperatorLoc(),
- diag::warn_impcast_bitfield_precision_constant)
- << PrettyValue << PrettyTrunc << RHS->getType()
- << E->getRHS()->getSourceRange();
-
- // Recurse, ignoring any implicit conversions on the RHS.
- return AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
- }
- }
+ if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
+ E->getOperatorLoc())) {
+ // Recurse, ignoring any implicit conversions on the RHS.
+ return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
+ E->getOperatorLoc());
}
}
@@ -2932,6 +2948,12 @@
AnalyzeImplicitConversions(*this, E, CC);
}
+void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
+ FieldDecl *BitField,
+ Expr *Init) {
+ (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
+}
+
/// CheckParmsForFunctionDef - Check that the parameters of the given
/// function are appropriate for the definition of a function. This
/// takes care of any checks that cannot be performed on the