Save FieldDecl BitWidth as a ConstantExpr

Author: tbaederr

clang/include/clang/AST/Decl.h

@@ -3143,7 +3143,7 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
 
   /// Computes the bit width of this field, if this is a bit field.
   /// May not be called on non-bitfields.
-  unsigned getBitWidthValue(const ASTContext &Ctx) const;
+  unsigned getBitWidthValue() const;
 
   /// Set the bit-field width for this member.
   // Note: used by some clients (i.e., do not remove it).
@@ -3174,7 +3174,7 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
   /// Is this a zero-length bit-field? Such bit-fields aren't really bit-fields
   /// at all and instead act as a separator between contiguous runs of other
   /// bit-fields.
-  bool isZeroLengthBitField(const ASTContext &Ctx) const;
+  bool isZeroLengthBitField() const;
 
   /// Determine if this field is a subobject of zero size, that is, either a
   /// zero-length bit-field or a field of empty class type with the

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -708,8 +708,7 @@ AST_MATCHER(FieldDecl, isBitField) {
 /// fieldDecl(hasBitWidth(2))
 ///   matches 'int a;' and 'int c;' but not 'int b;'.
 AST_MATCHER_P(FieldDecl, hasBitWidth, unsigned, Width) {
-  return Node.isBitField() &&
-         Node.getBitWidthValue(Finder->getASTContext()) == Width;
+  return Node.isBitField() && Node.getBitWidthValue() == Width;
 }
 
 /// Matches non-static data members that have an in-class initializer.

clang/lib/AST/ASTContext.cpp

@@ -2774,7 +2774,7 @@ getSubobjectSizeInBits(const FieldDecl *Field, const ASTContext &Context,
     if (Field->isUnnamedBitField())
       return 0;
 
-    int64_t BitfieldSize = Field->getBitWidthValue(Context);
+    int64_t BitfieldSize = Field->getBitWidthValue();
     if (IsBitIntType) {
       if ((unsigned)BitfieldSize >
           cast<BitIntType>(Field->getType())->getNumBits())
@@ -7745,7 +7745,7 @@ QualType ASTContext::isPromotableBitField(Expr *E) const {
 
   QualType FT = Field->getType();
 
-  uint64_t BitWidth = Field->getBitWidthValue(*this);
+  uint64_t BitWidth = Field->getBitWidthValue();
   uint64_t IntSize = getTypeSize(IntTy);
   // C++ [conv.prom]p5:
   //   A prvalue for an integral bit-field can be converted to a prvalue of type
@@ -8773,7 +8773,7 @@ static void EncodeBitField(const ASTContext *Ctx, std::string& S,
       S += getObjCEncodingForPrimitiveType(Ctx, BT);
     }
   }
-  S += llvm::utostr(FD->getBitWidthValue(*Ctx));
+  S += llvm::utostr(FD->getBitWidthValue());
 }
 
 // Helper function for determining whether the encoded type string would include
@@ -9199,7 +9199,7 @@ void ASTContext::getObjCEncodingForStructureImpl(RecordDecl *RDecl,
   }
 
   for (FieldDecl *Field : RDecl->fields()) {
-    if (!Field->isZeroLengthBitField(*this) && Field->isZeroSize(*this))
+    if (!Field->isZeroLengthBitField() && Field->isZeroSize(*this))
       continue;
     uint64_t offs = layout.getFieldOffset(Field->getFieldIndex());
     FieldOrBaseOffsets.insert(FieldOrBaseOffsets.upper_bound(offs),
@@ -9296,7 +9296,7 @@ void ASTContext::getObjCEncodingForStructureImpl(RecordDecl *RDecl,
       if (field->isBitField()) {
         EncodeBitField(this, S, field->getType(), field);
 #ifndef NDEBUG
-        CurOffs += field->getBitWidthValue(*this);
+        CurOffs += field->getBitWidthValue();
 #endif
       } else {
         QualType qt = field->getType();

clang/lib/AST/ByteCode/Interp.h

@@ -1489,8 +1489,7 @@ bool InitThisBitField(InterpState &S, CodePtr OpPC, const Record::Field *F,
     return false;
   const Pointer &Field = This.atField(FieldOffset);
   const auto &Value = S.Stk.pop<T>();
-  Field.deref<T>() =
-      Value.truncate(F->Decl->getBitWidthValue(S.getASTContext()));
+  Field.deref<T>() = Value.truncate(F->Decl->getBitWidthValue());
   Field.initialize();
   return true;
 }
@@ -1513,8 +1512,7 @@ bool InitBitField(InterpState &S, CodePtr OpPC, const Record::Field *F) {
   assert(F->isBitField());
   const T &Value = S.Stk.pop<T>();
   const Pointer &Field = S.Stk.peek<Pointer>().atField(F->Offset);
-  Field.deref<T>() =
-      Value.truncate(F->Decl->getBitWidthValue(S.getASTContext()));
+  Field.deref<T>() = Value.truncate(F->Decl->getBitWidthValue());
   Field.activate();
   Field.initialize();
   return true;
@@ -1821,7 +1819,7 @@ bool StoreBitField(InterpState &S, CodePtr OpPC) {
   if (Ptr.canBeInitialized())
     Ptr.initialize();
   if (const auto *FD = Ptr.getField())
-    Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue(S.getASTContext()));
+    Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue());
   else
     Ptr.deref<T>() = Value;
   return true;
@@ -1836,7 +1834,7 @@ bool StoreBitFieldPop(InterpState &S, CodePtr OpPC) {
   if (Ptr.canBeInitialized())
     Ptr.initialize();
   if (const auto *FD = Ptr.getField())
-    Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue(S.getASTContext()));
+    Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue());
   else
     Ptr.deref<T>() = Value;
   return true;

clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp

@@ -333,7 +333,7 @@ static bool readPointerToBuffer(const Context &Ctx, const Pointer &FromPtr,
 
         } else {
           if (const FieldDecl *FD = P.getField(); FD && FD->isBitField())
-            BitWidth = FD->getBitWidthValue(ASTCtx);
+            BitWidth = FD->getBitWidthValue();
           else if (T == PT_Bool && PackedBools)
             BitWidth = 1;
 

clang/lib/AST/Decl.cpp

@@ -4599,18 +4599,21 @@ void FieldDecl::setLazyInClassInitializer(LazyDeclStmtPtr NewInit) {
     Init = NewInit;
 }
 
-unsigned FieldDecl::getBitWidthValue(const ASTContext &Ctx) const {
+unsigned FieldDecl::getBitWidthValue() const {
   assert(isBitField() && "not a bitfield");
-  return getBitWidth()->EvaluateKnownConstInt(Ctx).getZExtValue();
+  return cast<ConstantExpr>(getBitWidth())
+      ->getAPValueResult()
+      .getInt()
+      .getZExtValue();
 }
 
-bool FieldDecl::isZeroLengthBitField(const ASTContext &Ctx) const {
+bool FieldDecl::isZeroLengthBitField() const {
   return isUnnamedBitField() && !getBitWidth()->isValueDependent() &&
-         getBitWidthValue(Ctx) == 0;
+         getBitWidthValue() == 0;
 }
 
 bool FieldDecl::isZeroSize(const ASTContext &Ctx) const {
-  if (isZeroLengthBitField(Ctx))
+  if (isZeroLengthBitField())
     return true;
 
   // C++2a [intro.object]p7:

clang/lib/AST/DeclCXX.cpp

@@ -993,7 +993,7 @@ void CXXRecordDecl::addedMember(Decl *D) {
       // C++ [meta.unary.prop]p4: [LWG2358]
       //   T is a class type [...] with [...] no unnamed bit-fields of non-zero
       //   length
-      if (data().Empty && !Field->isZeroLengthBitField(Context) &&
+      if (data().Empty && !Field->isZeroLengthBitField() &&
           Context.getLangOpts().getClangABICompat() >
               LangOptions::ClangABI::Ver6)
         data().Empty = false;

clang/lib/AST/Expr.cpp

@@ -196,8 +196,7 @@ bool Expr::isKnownToHaveBooleanValue(bool Semantic) const {
 
   if (const FieldDecl *FD = E->getSourceBitField())
     if (!Semantic && FD->getType()->isUnsignedIntegerType() &&
-        !FD->getBitWidth()->isValueDependent() &&
-        FD->getBitWidthValue(FD->getASTContext()) == 1)
+        !FD->getBitWidth()->isValueDependent() && FD->getBitWidthValue() == 1)
       return true;
 
   return false;

clang/lib/AST/ExprConstant.cpp

@@ -2875,7 +2875,7 @@ static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
 
   APSInt &Int = Value.getInt();
   unsigned OldBitWidth = Int.getBitWidth();
-  unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
+  unsigned NewBitWidth = FD->getBitWidthValue();
   if (NewBitWidth < OldBitWidth)
     Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
   return true;

clang/lib/AST/Randstruct.cpp

@@ -91,7 +91,7 @@ void randomizeStructureLayoutImpl(const ASTContext &Context,
     auto FieldIter = FieldsOut.begin();
     FieldDecl *FD = *FieldIter;
 
-    if (FD->isBitField() && !FD->isZeroLengthBitField(Context)) {
+    if (FD->isBitField() && !FD->isZeroLengthBitField()) {
       // Start a bitfield run if this is the first bitfield we have found.
       if (!CurrentBitfieldRun)
         CurrentBitfieldRun = std::make_unique<BitfieldRunBucket>();