r283063 - Alias must point to a definition

[Yaron Keren via cfe-commits]

yes, it works, thanks!

2016-10-03 18:19 GMT+03:00 Aditya K <hiraditya at msn.com>:

> Thanks for poining that out. I have updated the test case, please see if
> that works.
>
>
> http://llvm.org/viewvc/llvm-project?view=revision&revision=283085
>
>
>
> -Aditya
>
>
> ------------------------------
> *From:* Yaron Keren <yaron.keren at gmail.com>
> *Sent:* Sunday, October 2, 2016 11:32 AM
> *To:* Aditya Kumar
> *Cc:* cfe-commits
> *Subject:* Re: r283063 - Alias must point to a definition
>
> The mangling is different when targeting MSVC ABI, see failure at
>
> http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/
> builds/29889/steps/test_all/logs/Clang%20%3A%3A%
> 20CodeGenCXX__alias-available-externally.cpp
>
> maybe   -triple x86_64-pc-linux  ?
>
> 2016-10-02 6:06 GMT+03:00 Aditya Kumar via cfe-commits <
> cfe-commits at lists.llvm.org>:
>
>> Author: hiraditya
>> Date: Sat Oct  1 22:06:36 2016
>> New Revision: 283063
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=283063&view=rev
>> Log:
>> Alias must point to a definition
>>
>> Reapplying the patch after modifying the test case.
>>
>> Inlining the destructor caused the compiler to generate bad IR which
>> failed the Verifier in the backend.
>> https://llvm.org/bugs/show_bug.cgi?id=30341
>>
>> This patch disables alias to available_externally definitions.
>>
>> Reviewers: eugenis, rsmith
>>
>> Differential Revision: https://reviews.llvm.org/D24682
>>
>> Added:
>>     cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp
>> Modified:
>>     cfe/trunk/lib/CodeGen/CGCXX.cpp
>>
>> Modified: cfe/trunk/lib/CodeGen/CGCXX.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CG
>> CXX.cpp?rev=283063&r1=283062&r2=283063&view=diff
>> ============================================================
>> ==================
>> --- cfe/trunk/lib/CodeGen/CGCXX.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CGCXX.cpp Sat Oct  1 22:06:36 2016
>> @@ -134,6 +134,11 @@ bool CodeGenModule::TryEmitDefinitionAsA
>>    llvm::GlobalValue::LinkageTypes TargetLinkage =
>>        getFunctionLinkage(TargetDecl);
>>
>> +  // available_externally definitions aren't real definitions, so we
>> cannot
>> +  // create an alias to one.
>> +  if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage)
>> +    return true;
>> +
>>    // Check if we have it already.
>>    StringRef MangledName = getMangledName(AliasDecl);
>>    llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
>> @@ -156,14 +161,7 @@ bool CodeGenModule::TryEmitDefinitionAsA
>>
>>    // Instead of creating as alias to a linkonce_odr, replace all of the
>> uses
>>    // of the aliasee.
>> -  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) &&
>> -     (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage ||
>> -      !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) {
>> -    // FIXME: An extern template instantiation will create functions with
>> -    // linkage "AvailableExternally". In libc++, some classes also define
>> -    // members with attribute "AlwaysInline" and expect no reference to
>> -    // be generated. It is desirable to reenable this optimisation after
>> -    // corresponding LLVM changes.
>> +  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage)) {
>>      addReplacement(MangledName, Aliasee);
>>      return false;
>>    }
>>
>> Added: cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCX
>> X/alias-available-externally.cpp?rev=283063&view=auto
>> ============================================================
>> ==================
>> --- cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp (added)
>> +++ cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp Sat Oct  1
>> 22:06:36 2016
>> @@ -0,0 +1,20 @@
>> +// RUN: %clang_cc1 -O1 -std=c++11 -emit-llvm -disable-llvm-passes -o -
>> %s | FileCheck %s
>> +// Clang should not generate alias to available_externally definitions.
>> +// Check that the destructor of Foo is defined.
>> +// The destructors have different return type for different targets.
>> +// CHECK: define linkonce_odr {{.*}} @_ZN3FooD2Ev
>> +template <class CharT>
>> +struct String {
>> +  String() {}
>> +  ~String();
>> +};
>> +
>> +template <class CharT>
>> +inline __attribute__((visibility("hidden"), always_inline))
>> +String<CharT>::~String() {}
>> +
>> +extern template struct String<char>;
>> +
>> +struct Foo : public String<char> { Foo() { String<char> s; } };
>> +
>> +Foo f;
>>
>>
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