[cfe-commits] r127702 - in /cfe/trunk: lib/CodeGen/CGExprConstant.cpp test/CodeGenCXX/member-function-pointers.cpp

[John McCall]

On Mar 16, 2011, at 2:33 PM, Matt Beaumont-Gay wrote:

> Hi John,
> '
> On Tue, Mar 15, 2011 at 14:17, John McCall <rjmccall at apple.com> wrote:
>> Author: rjmccall
>> Date: Tue Mar 15 16:17:48 2011
>> New Revision: 127702
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=127702&view=rev
>> Log:
>> Reorganize the emission of (unfoldable) constant casts a bit, and
>> make sure that upcasts of member pointer types are covered as constants.
>> Fixed rdar://problem/9130221
>> 
>> 
>> Modified:
>>    cfe/trunk/lib/CodeGen/CGExprConstant.cpp
>>    cfe/trunk/test/CodeGenCXX/member-function-pointers.cpp
>> 
>> Modified: cfe/trunk/lib/CodeGen/CGExprConstant.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprConstant.cpp?rev=127702&r1=127701&r2=127702&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/CodeGen/CGExprConstant.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CGExprConstant.cpp Tue Mar 15 16:17:48 2011
>> @@ -483,18 +483,17 @@
>>   }
>> 
>>   llvm::Constant *VisitCastExpr(CastExpr* E) {
>> +    Expr *subExpr = E->getSubExpr();
>> +    llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF);
>> +    if (!C) return 0;
>> +
>> +    const llvm::Type *destType = ConvertType(E->getType());
>> +
>>     switch (E->getCastKind()) {
>>     case CK_ToUnion: {
>>       // GCC cast to union extension
>>       assert(E->getType()->isUnionType() &&
>>              "Destination type is not union type!");
>> -      const llvm::Type *Ty = ConvertType(E->getType());
>> -      Expr *SubExpr = E->getSubExpr();
>> -
>> -      llvm::Constant *C =
>> -        CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF);
>> -      if (!C)
>> -        return 0;
>> 
>>       // Build a struct with the union sub-element as the first member,
>>       // and padded to the appropriate size
>> @@ -503,7 +502,7 @@
>>       Elts.push_back(C);
>>       Types.push_back(C->getType());
>>       unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType());
>> -      unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty);
>> +      unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(destType);
>> 
>>       assert(CurSize <= TotalSize && "Union size mismatch!");
>>       if (unsigned NumPadBytes = TotalSize - CurSize) {
>> @@ -523,39 +522,101 @@
>>       const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
>>       return CGM.getCXXABI().EmitNullMemberPointer(MPT);
>>     }
>> -
>> -    case CK_BaseToDerivedMemberPointer: {
>> -      Expr *SubExpr = E->getSubExpr();
>> -      llvm::Constant *C =
>> -        CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF);
>> -      if (!C) return 0;
>> 
>> +    case CK_DerivedToBaseMemberPointer:
>> +    case CK_BaseToDerivedMemberPointer:
>>       return CGM.getCXXABI().EmitMemberPointerConversion(C, E);
>> -    }
>> 
>> -    case CK_BitCast:
>> -      // This must be a member function pointer cast.
>> -      return Visit(E->getSubExpr());
>> -
>> -    default: {
>> -      // FIXME: This should be handled by the CK_NoOp cast kind.
>> -      // Explicit and implicit no-op casts
>> -      QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType();
>> -      if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy))
>> -        return Visit(E->getSubExpr());
>> -
>> -      // Handle integer->integer casts for address-of-label differences.
>> -      if (Ty->isIntegerType() && SubTy->isIntegerType() &&
>> -          CGF) {
>> -        llvm::Value *Src = Visit(E->getSubExpr());
>> -        if (Src == 0) return 0;
>> -
>> -        // Use EmitScalarConversion to perform the conversion.
>> -        return cast<llvm::Constant>(CGF->EmitScalarConversion(Src, SubTy, Ty));
>> -      }
>> -
>> +    case CK_LValueToRValue:
>> +    case CK_NoOp:
>> +      return C;
>> +
>> +    case CK_AnyPointerToObjCPointerCast:
>> +    case CK_AnyPointerToBlockPointerCast:
>> +    case CK_LValueBitCast:
>> +    case CK_BitCast:
>> +      if (C->getType() == destType) return C;
>> +      return llvm::ConstantExpr::getBitCast(C, destType);
>> +
>> +    case CK_Dependent: llvm_unreachable("saw dependent cast!");
>> +
>> +    // These will never be supported.
>> +    case CK_ObjCObjectLValueCast:
>> +    case CK_GetObjCProperty:
>> +    case CK_ToVoid:
>> +    case CK_Dynamic:
>>       return 0;
>> +
>> +    // These might need to be supported for constexpr.
>> +    case CK_UserDefinedConversion:
>> +    case CK_ConstructorConversion:
>> +      return 0;
>> +
>> +    // These should eventually be supported.
>> +    case CK_ArrayToPointerDecay:
>> +    case CK_FunctionToPointerDecay:
>> +    case CK_BaseToDerived:
>> +    case CK_DerivedToBase:
>> +    case CK_UncheckedDerivedToBase:
>> +    case CK_MemberPointerToBoolean:
>> +    case CK_VectorSplat:
>> +    case CK_FloatingRealToComplex:
>> +    case CK_FloatingComplexToReal:
>> +    case CK_FloatingComplexToBoolean:
>> +    case CK_FloatingComplexCast:
>> +    case CK_FloatingComplexToIntegralComplex:
>> +    case CK_IntegralRealToComplex:
>> +    case CK_IntegralComplexToReal:
>> +    case CK_IntegralComplexToBoolean:
>> +    case CK_IntegralComplexCast:
>> +    case CK_IntegralComplexToFloatingComplex:
>> +      return 0;
>> +
>> +    case CK_PointerToIntegral:
>> +      if (!E->getType()->isBooleanType())
>> +        return llvm::ConstantExpr::getPtrToInt(C, destType);
>> +      // fallthrough
>> +
>> +    case CK_PointerToBoolean:
>> +      return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C,
>> +        llvm::ConstantPointerNull::get(cast<llvm::PointerType>(C->getType())));
>> +
>> +    case CK_NullToPointer:
>> +      return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(destType));
>> +
>> +    case CK_IntegralCast: {
>> +      bool isSigned = subExpr->getType()->isSignedIntegerType();
>> +      return llvm::ConstantExpr::getIntegerCast(C, destType, isSigned);
>> +    }
>> +
>> +    case CK_IntegralToPointer: {
>> +      bool isSigned = subExpr->getType()->isSignedIntegerType();
>> +      C = llvm::ConstantExpr::getIntegerCast(C, CGM.IntPtrTy, isSigned);
>> +      return llvm::ConstantExpr::getIntToPtr(C, destType);
>>     }
>> +
>> +    case CK_IntegralToBoolean:
>> +      return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C,
>> +                             llvm::Constant::getNullValue(C->getType()));
>> +
>> +    case CK_IntegralToFloating:
>> +      if (subExpr->getType()->isSignedIntegerType())
>> +        return llvm::ConstantExpr::getSIToFP(C, destType);
>> +      else
>> +        return llvm::ConstantExpr::getUIToFP(C, destType);
>> +
>> +    case CK_FloatingToIntegral:
>> +      if (E->getType()->isSignedIntegerType())
>> +        return llvm::ConstantExpr::getFPToSI(C, destType);
>> +      else
>> +        return llvm::ConstantExpr::getFPToUI(C, destType);
>> +
>> +    case CK_FloatingToBoolean:
>> +      return llvm::ConstantExpr::getFCmp(llvm::CmpInst::FCMP_UNE, C,
>> +                             llvm::Constant::getNullValue(C->getType()));
>> +
>> +    case CK_FloatingCast:
>> +      return llvm::ConstantExpr::getFPCast(C, destType);
>>     }
>>   }
> 
> Here's the latest salvo in my continuing feud with GCC's -Wreturn-type:
> tools/clang/lib/CodeGen/CGExprConstant.cpp: In member function
> 'llvm::Constant*<unnamed>::ConstExprEmitter::VisitCastExpr(clang::CastExpr*)':
> tools/clang/lib/CodeGen/CGExprConstant.cpp:621: error: control reaches
> end of non-void function
> 
> Is the new llvm_unreachable the right tool here? E.g.:

Yes, that should work.  The old llvm_unreachable would have worked fine, too.

John.