Author: rnk
Date: Mon Mar 13 17:33:04 2017
New Revision: 297680
URL: http://llvm.org/viewvc/llvm-project?rev=297680&view=rev
Log:
Widen AST bitfields too small to represent all enumerators
All of these were found by a new warning that I am prototyping,
-Wbitfield-enum-conversion.
Stmt::ExprBits::ObjectKind - This was not wide enough to represent
OK_ObjSubscript, so this was a real, true positive bug.
ObjCDeclSpec::objCDeclQualifier - On Windows, setting DQ_CSNullability
would cause the bitfield to become negative because enum types are
always implicitly 'int' there. This would probably never be noticed
because this is a flag-style enum, so we only ever test one bit at a
time. Switching to 'unsigned' also makes this type pack smaller on
Windows.
FunctionDecl::SClass - Technically, we only need two bits for all valid
function storage classes. Functions can never have automatic or register
storage class. This seems a bit too clever, and we have a bit to spare,
so widening the bitfield seems like the best way to pacify the warning.
You could classify this as a false positive, but widening the bitfield
defends us from invalid ASTs.
Modified:
cfe/trunk/include/clang/AST/Decl.h
cfe/trunk/include/clang/AST/Expr.h
cfe/trunk/include/clang/AST/Stmt.h
cfe/trunk/include/clang/Sema/DeclSpec.h
Modified: cfe/trunk/include/clang/AST/Decl.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=297680&r1=297679&r2=297680&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Mon Mar 13 17:33:04 2017
@@ -1605,7 +1605,7 @@ private:
// FIXME: This can be packed into the bitfields in DeclContext.
// NOTE: VC++ packs bitfields poorly if the types differ.
- unsigned SClass : 2;
+ unsigned SClass : 3;
unsigned IsInline : 1;
unsigned IsInlineSpecified : 1;
protected:
Modified: cfe/trunk/include/clang/AST/Expr.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=297680&r1=297679&r2=297680&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Expr.h (original)
+++ cfe/trunk/include/clang/AST/Expr.h Mon Mar 13 17:33:04 2017
@@ -115,6 +115,7 @@ protected:
ExprBits.InstantiationDependent = ID;
ExprBits.ValueKind = VK;
ExprBits.ObjectKind = OK;
+ assert(ExprBits.ObjectKind == OK && "truncated kind");
ExprBits.ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
setType(T);
}
Modified: cfe/trunk/include/clang/AST/Stmt.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Stmt.h?rev=297680&r1=297679&r2=297680&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Stmt.h (original)
+++ cfe/trunk/include/clang/AST/Stmt.h Mon Mar 13 17:33:04 2017
@@ -127,13 +127,13 @@ protected:
unsigned : NumStmtBits;
unsigned ValueKind : 2;
- unsigned ObjectKind : 2;
+ unsigned ObjectKind : 3;
unsigned TypeDependent : 1;
unsigned ValueDependent : 1;
unsigned InstantiationDependent : 1;
unsigned ContainsUnexpandedParameterPack : 1;
};
- enum { NumExprBits = 16 };
+ enum { NumExprBits = 17 };
class CharacterLiteralBitfields {
friend class CharacterLiteral;
@@ -350,6 +350,8 @@ protected:
public:
Stmt(StmtClass SC) {
+ static_assert(sizeof(*this) == sizeof(void *),
+ "changing bitfields changed sizeof(Stmt)");
static_assert(sizeof(*this) % alignof(void *) == 0,
"Insufficient alignment!");
StmtBits.sClass = SC;
Modified: cfe/trunk/include/clang/Sema/DeclSpec.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/DeclSpec.h?rev=297680&r1=297679&r2=297680&view=diff
==============================================================================
--- cfe/trunk/include/clang/Sema/DeclSpec.h (original)
+++ cfe/trunk/include/clang/Sema/DeclSpec.h Mon Mar 13 17:33:04 2017
@@ -819,7 +819,9 @@ public:
: objcDeclQualifier(DQ_None), PropertyAttributes(DQ_PR_noattr),
Nullability(0), GetterName(nullptr), SetterName(nullptr) { }
- ObjCDeclQualifier getObjCDeclQualifier() const { return objcDeclQualifier; }
+ ObjCDeclQualifier getObjCDeclQualifier() const {
+ return (ObjCDeclQualifier)objcDeclQualifier;
+ }
void setObjCDeclQualifier(ObjCDeclQualifier DQVal) {
objcDeclQualifier = (ObjCDeclQualifier) (objcDeclQualifier | DQVal);
}
@@ -869,7 +871,7 @@ private:
// FIXME: These two are unrelated and mutually exclusive. So perhaps
// we can put them in a union to reflect their mutual exclusivity
// (space saving is negligible).
- ObjCDeclQualifier objcDeclQualifier : 7;
+ unsigned objcDeclQualifier : 7;
// NOTE: VC++ treats enums as signed, avoid using ObjCPropertyAttributeKind
unsigned PropertyAttributes : 15;
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