r246830 - Fix a potential APInt memory leak when using __attribute__((flag_enum)), and

Steven Wu via cfe-commits cfe-commits at lists.llvm.org
Thu Sep 3 21:21:35 PDT 2015


Sorry I just get back to my computer. I will watch the bots going. I will try investigating if it is still failing.
As far as I know, there is no special settingl about the bots and all our bots are complaining about it. 

Steven

> On Sep 3, 2015, at 9:09 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> 
> OK, should be fixed in r246836.
> 
> On Thu, Sep 3, 2015 at 7:50 PM, Richard Smith <richard at metafoo.co.uk <mailto:richard at metafoo.co.uk>> wrote:
> On Thu, Sep 3, 2015 at 6:21 PM, Steven Wu via cfe-commits <cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
> In case you didn’t get an email from the failure because it was overshadowed by the previous error. This commit seems to break the green dragon bots:
> http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-incremental_check/12990/testReport/junit/Clang/Sema/attr_flag_enum_c/ <http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-incremental_check/12990/testReport/junit/Clang/Sema/attr_flag_enum_c/>
> 
> I have no idea what's wrong here; is there anything unusual about that bot that might give me a clue? (This bot: http://lab.llvm.org:8011/builders/clang-x64-ninja-win7/builds/4637 <http://lab.llvm.org:8011/builders/clang-x64-ninja-win7/builds/4637> seems to be failing the same way.)
>  
> Thanks
> 
> Steven
> 
>> On Sep 3, 2015, at 6:03 PM, Richard Smith via cfe-commits <cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
>> 
>> Author: rsmith
>> Date: Thu Sep  3 20:03:03 2015
>> New Revision: 246830
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=246830&view=rev <http://llvm.org/viewvc/llvm-project?rev=246830&view=rev>
>> Log:
>> Fix a potential APInt memory leak when using __attribute__((flag_enum)), and
>> simplify the implementation a bit.
>> 
>> Modified:
>>    cfe/trunk/include/clang/Basic/Attr.td
>>    cfe/trunk/include/clang/Sema/Sema.h
>>    cfe/trunk/lib/Sema/SemaDecl.cpp
>>    cfe/trunk/lib/Sema/SemaStmt.cpp
>> 
>> Modified: cfe/trunk/include/clang/Basic/Attr.td
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=246830&r1=246829&r2=246830&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=246830&r1=246829&r2=246830&view=diff>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/Attr.td (original)
>> +++ cfe/trunk/include/clang/Basic/Attr.td Thu Sep  3 20:03:03 2015
>> @@ -747,18 +747,6 @@ def FlagEnum : InheritableAttr {
>>   let Subjects = SubjectList<[Enum]>;
>>   let Documentation = [FlagEnumDocs];
>>   let LangOpts = [COnly];
>> -  let AdditionalMembers = [{
>> -private:
>> -    llvm::APInt FlagBits;
>> -public:
>> -    llvm::APInt &getFlagBits() {
>> -      return FlagBits;
>> -    }
>> -
>> -    const llvm::APInt &getFlagBits() const {
>> -      return FlagBits;
>> -    }
>> -}];
>> }
>> 
>> def Flatten : InheritableAttr {
>> 
>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=246830&r1=246829&r2=246830&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=246830&r1=246829&r2=246830&view=diff>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>> +++ cfe/trunk/include/clang/Sema/Sema.h Thu Sep  3 20:03:03 2015
>> @@ -903,6 +903,10 @@ public:
>>   /// for C++ records.
>>   llvm::FoldingSet<SpecialMemberOverloadResult> SpecialMemberCache;
>> 
>> +  /// \brief A cache of the flags available in enumerations with the flag_bits
>> +  /// attribute.
>> +  mutable llvm::DenseMap<const EnumDecl*, llvm::APInt> FlagBitsCache;
>> +
>>   /// \brief The kind of translation unit we are processing.
>>   ///
>>   /// When we're processing a complete translation unit, Sema will perform
>> 
>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=246830&r1=246829&r2=246830&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=246830&r1=246829&r2=246830&view=diff>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Sep  3 20:03:03 2015
>> @@ -14017,14 +14017,21 @@ static void CheckForDuplicateEnumValues(
>> bool
>> Sema::IsValueInFlagEnum(const EnumDecl *ED, const llvm::APInt &Val,
>>                         bool AllowMask) const {
>> -  FlagEnumAttr *FEAttr = ED->getAttr<FlagEnumAttr>();
>> -  assert(FEAttr && "looking for value in non-flag enum");
>> +  assert(ED->hasAttr<FlagEnumAttr>() && "looking for value in non-flag enum");
>> 
>> -  llvm::APInt FlagMask = ~FEAttr->getFlagBits();
>> -  unsigned Width = FlagMask.getBitWidth();
>> +  auto R = FlagBitsCache.insert(std::make_pair(ED, llvm::APInt()));
>> +  llvm::APInt &FlagBits = R.first->second;
>> 
>> -  // We will try a zero-extended value for the regular check first.
>> -  llvm::APInt ExtVal = Val.zextOrSelf(Width);
>> +  if (R.second) {
>> +    for (auto *E : ED->enumerators()) {
>> +      const auto &Val = E->getInitVal();
>> +      // Only single-bit enumerators introduce new flag values.
>> +      if (Val.isPowerOf2())
>> +        FlagBits = FlagBits.zextOrSelf(Val.getBitWidth()) | Val;
>> +    }
>> +  }
>> +
>> +  llvm::APInt FlagMask = ~FlagBits.zextOrTrunc(Val.getBitWidth());
>> 
>>   // A value is in a flag enum if either its bits are a subset of the enum's
>>   // flag bits (the first condition) or we are allowing masks and the same is
>> @@ -14034,26 +14041,10 @@ Sema::IsValueInFlagEnum(const EnumDecl *
>>   // While it's true that any value could be used as a mask, the assumption is
>>   // that a mask will have all of the insignificant bits set. Anything else is
>>   // likely a logic error.
>> -  if (!(FlagMask & ExtVal))
>> +  if (!(FlagMask & Val) ||
>> +      (AllowMask && !(FlagMask & ~Val)))
>>     return true;
>> 
>> -  if (AllowMask) {
>> -    // Try a one-extended value instead. This can happen if the enum is wider
>> -    // than the constant used, in C with extensions to allow for wider enums.
>> -    // The mask will still have the correct behaviour, so we give the user the
>> -    // benefit of the doubt.
>> -    //
>> -    // FIXME: This heuristic can cause weird results if the enum was extended
>> -    // to a larger type and is signed, because then bit-masks of smaller types
>> -    // that get extended will fall out of range (e.g. ~0x1u). We currently don't
>> -    // detect that case and will get a false positive for it. In most cases,
>> -    // though, it can be fixed by making it a signed type (e.g. ~0x1), so it may
>> -    // be fine just to accept this as a warning.
>> -    ExtVal |= llvm::APInt::getHighBitsSet(Width, Width - Val.getBitWidth());
>> -    if (!(FlagMask & ~ExtVal))
>> -      return true;
>> -  }
>> -
>>   return false;
>> }
>> 
>> @@ -14208,13 +14199,8 @@ void Sema::ActOnEnumBody(SourceLocation
>>     }
>>   }
>> 
>> -  FlagEnumAttr *FEAttr = Enum->getAttr<FlagEnumAttr>();
>> -  if (FEAttr)
>> -    FEAttr->getFlagBits() = llvm::APInt(BestWidth, 0);
>> -
>>   // Loop over all of the enumerator constants, changing their types to match
>> -  // the type of the enum if needed. If we have a flag type, we also prepare the
>> -  // FlagBits cache.
>> +  // the type of the enum if needed.
>>   for (auto *D : Elements) {
>>     auto *ECD = cast_or_null<EnumConstantDecl>(D);
>>     if (!ECD) continue;  // Already issued a diagnostic.
>> @@ -14246,7 +14232,7 @@ void Sema::ActOnEnumBody(SourceLocation
>>         // enum-specifier, each enumerator has the type of its
>>         // enumeration.
>>         ECD->setType(EnumType);
>> -      goto flagbits;
>> +      continue;
>>     } else {
>>       NewTy = BestType;
>>       NewWidth = BestWidth;
>> @@ -14273,32 +14259,21 @@ void Sema::ActOnEnumBody(SourceLocation
>>       ECD->setType(EnumType);
>>     else
>>       ECD->setType(NewTy);
>> -
>> -flagbits:
>> -    // Check to see if we have a constant with exactly one bit set. Note that x
>> -    // & (x - 1) will be nonzero if and only if x has more than one bit set.
>> -    if (FEAttr) {
>> -      llvm::APInt ExtVal = InitVal.zextOrSelf(BestWidth);
>> -      if (ExtVal != 0 && !(ExtVal & (ExtVal - 1))) {
>> -        FEAttr->getFlagBits() |= ExtVal;
>> -      }
>> -    }
>>   }
>> 
>> -  if (FEAttr) {
>> +  if (Enum->hasAttr<FlagEnumAttr>()) {
>>     for (Decl *D : Elements) {
>>       EnumConstantDecl *ECD = cast_or_null<EnumConstantDecl>(D);
>>       if (!ECD) continue;  // Already issued a diagnostic.
>> 
>>       llvm::APSInt InitVal = ECD->getInitVal();
>> -      if (InitVal != 0 && !IsValueInFlagEnum(Enum, InitVal, true))
>> +      if (InitVal != 0 && !InitVal.isPowerOf2() &&
>> +          !IsValueInFlagEnum(Enum, InitVal, true))
>>         Diag(ECD->getLocation(), diag::warn_flag_enum_constant_out_of_range)
>>           << ECD << Enum;
>>     }
>>   }
>> 
>> -
>> -
>>   Enum->completeDefinition(BestType, BestPromotionType,
>>                            NumPositiveBits, NumNegativeBits);
>> 
>> 
>> Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=246830&r1=246829&r2=246830&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=246830&r1=246829&r2=246830&view=diff>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaStmt.cpp Thu Sep  3 20:03:03 2015
>> @@ -698,8 +698,6 @@ static bool ShouldDiagnoseSwitchCaseNotI
>>                                               EnumValsTy::iterator &EI,
>>                                               EnumValsTy::iterator &EIEnd,
>>                                               const llvm::APSInt &Val) {
>> -  bool FlagType = ED->hasAttr<FlagEnumAttr>();
>> -
>>   if (const DeclRefExpr *DRE =
>>           dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
>>     if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
>> @@ -711,7 +709,7 @@ static bool ShouldDiagnoseSwitchCaseNotI
>>     }
>>   }
>> 
>> -  if (FlagType) {
>> +  if (ED->hasAttr<FlagEnumAttr>()) {
>>     return !S.IsValueInFlagEnum(ED, Val, false);
>>   } else {
>>     while (EI != EIEnd && EI->first < Val)
>> 
>> 
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