r348276 - [AST][NFC] Make ArrayTypeTraitExpr non polymorphic
Bruno Ricci via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 11 08:49:48 PST 2018
Hi Mikael,
I can indeed reproduce this with gcc 5.5.0 when doing a Release
build with assertions. I cannot reproduce this with gcc 6.5.0
(also with a Release build with assertions), nor can I reproduce
this with clang 7 (also with a Release build with assertions).
I tried to instrument StringRefCheckerVisitor::VisitChildren but this
just causes the stack overflow to move to CGBuilder.
What is stranger is that the reproducer do not even causes
an ArrayTypeTraitExpr node to be created.
Increasing the maximum stack size with ulimit by a small amount fixes
the problem, so I don't think this is a mis-compilation either.
I think that this change is correct since no one is using the polymorphism
of ArrayTypeTraitExpr. Indeed taking the blunt step of making it final do
not causes any failure.
The only possible explaination I can think of is that for one reason
or another, with this particular compiler + build settings, this change
causes an increase of stack usage which exceeed the default limit ?
Regards,
Bruno
On 11/12/2018 14:13, Mikael Holmén wrote:
> Hi Bruno,
>
> I've no idea if this is really related to your change, but with this
> commit, the following starts crashing:
>
> clang-tidy -allow-enabling-analyzer-alpha-checkers
> -checks='-*,clang-analyzer-*' ./reduced.c --
>
> It seems like it recurses forever for some reason, and then we run out
> of stack and it crashes:
>
> elxhw7c132-n7[llvm]: build-all-bbigcc/bin/clang-tidy
> -allow-enabling-analyzer-alpha-checkers -checks='-*,clang-analyzer-*'
> ./reduced.c --
> #0 0x000000000074fbda llvm::sys::PrintStackTrace(llvm::raw_ostream&)
> (build-all-bbigcc/bin/clang-tidy+0x74fbda)
> #1 0x000000000074e0aa llvm::sys::RunSignalHandlers()
> (build-all-bbigcc/bin/clang-tidy+0x74e0aa)
> #2 0x000000000074e1d7 SignalHandler(int)
> (build-all-bbigcc/bin/clang-tidy+0x74e1d7)
> #3 0x00007f6cd7f84330 __restore_rt
> (/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
> #4 0x0000000000f06c63 clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (build-all-bbigcc/bin/clang-tidy+0xf06c63)
> #5 0x0000000000f0a282 (anonymous
> namespace)::StringRefCheckerVisitor::VisitChildren(clang::Stmt*)
> (build-all-bbigcc/bin/clang-tidy+0xf0a282)
> #6 0x0000000000f0527f clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (.part.132)
> (build-all-bbigcc/bin/clang-tidy+0xf0527f)
> #7 0x0000000000f06c68 clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (build-all-bbigcc/bin/clang-tidy+0xf06c68)
> #8 0x0000000000f0a282 (anonymous
> namespace)::StringRefCheckerVisitor::VisitChildren(clang::Stmt*)
> (build-all-bbigcc/bin/clang-tidy+0xf0a282)
> #9 0x0000000000f03fcf clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (.part.132)
> (build-all-bbigcc/bin/clang-tidy+0xf03fcf)
> #10 0x0000000000f06c68 clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (build-all-bbigcc/bin/clang-tidy+0xf06c68)
> #11 0x0000000000f0a282 (anonymous
> namespace)::StringRefCheckerVisitor::VisitChildren(clang::Stmt*)
> (build-all-bbigcc/bin/clang-tidy+0xf0a282)
> #12 0x0000000000f03fcf clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (.part.132)
> (build-all-bbigcc/bin/clang-tidy+0xf03fcf)
> #13 0x0000000000f06c68 clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (build-all-bbigcc/bin/clang-tidy+0xf06c68)
> #14 0x0000000000f0a282 (anonymous
> namespace)::StringRefCheckerVisitor::VisitChildren(clang::Stmt*)
> (build-all-bbigcc/bin/clang-tidy+0xf0a282)
> #15 0x0000000000f03fcf clang::StmtVisitorBase<std::add_pointer,
> (anonymous namespace)::StringRefCheckerVisitor,
> void>::Visit(clang::Stmt*) (.part.132)
> (build-all-bbigcc/bin/clang-tidy+0xf03fcf)
>
> etc
>
> I've only seen this when I compile clang-tidy with gcc 5.4.0, assertions
> on, with optimizations. Simply turning on debug info when compiling
> clang-tidy makes the crash go away so it's quite fragile.
>
> Regards,
> Mikael
>
> On 12/4/18 5:01 PM, Bruno Ricci via cfe-commits wrote:
>> Author: brunoricci
>> Date: Tue Dec 4 08:01:24 2018
>> New Revision: 348276
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=348276&view=rev
>> Log:
>> [AST][NFC] Make ArrayTypeTraitExpr non polymorphic
>>
>> ArrayTypeTraitExpr is the only expression class which is polymorphic.
>> As far as I can tell this is completely pointless.
>>
>> Differential Revision: https://reviews.llvm.org/D55221
>>
>> Reviewed By: aaron.ballman
>>
>>
>> Modified:
>> cfe/trunk/include/clang/AST/ExprCXX.h
>> cfe/trunk/lib/AST/ExprCXX.cpp
>>
>> Modified: cfe/trunk/include/clang/AST/ExprCXX.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/ExprCXX.h?rev=348276&r1=348275&r2=348276&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/AST/ExprCXX.h (original)
>> +++ cfe/trunk/include/clang/AST/ExprCXX.h Tue Dec 4 08:01:24 2018
>> @@ -2455,8 +2455,6 @@ class ArrayTypeTraitExpr : public Expr {
>> /// The type being queried.
>> TypeSourceInfo *QueriedType = nullptr;
>>
>> - virtual void anchor();
>> -
>> public:
>> friend class ASTStmtReader;
>>
>> @@ -2474,8 +2472,6 @@ public:
>> explicit ArrayTypeTraitExpr(EmptyShell Empty)
>> : Expr(ArrayTypeTraitExprClass, Empty), ATT(0) {}
>>
>> - virtual ~ArrayTypeTraitExpr() = default;
>> -
>> SourceLocation getBeginLoc() const LLVM_READONLY { return Loc; }
>> SourceLocation getEndLoc() const LLVM_READONLY { return RParen; }
>>
>>
>> Modified: cfe/trunk/lib/AST/ExprCXX.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprCXX.cpp?rev=348276&r1=348275&r2=348276&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/AST/ExprCXX.cpp (original)
>> +++ cfe/trunk/lib/AST/ExprCXX.cpp Tue Dec 4 08:01:24 2018
>> @@ -1443,5 +1443,3 @@ TypeTraitExpr *TypeTraitExpr::CreateDese
>> void *Mem = C.Allocate(totalSizeToAlloc<TypeSourceInfo *>(NumArgs));
>> return new (Mem) TypeTraitExpr(EmptyShell());
>> }
>> -
>> -void ArrayTypeTraitExpr::anchor() {}
>>
>>
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