[PATCH] -Wprofile-instr-out-of-date warnings due to certain destructor types not being assigned increment intrinsics

[Justin Bogner]

Betul Buyukkurt <betulb at codeaurora.org> writes:
> Hi bogner, dsule, davidxl,
>
> -fprofile-instr-generate does not emit counter increment intrinsics
> for Dtor_Deleting and Dtor_Complete destructors with assigned
> counters. This causes unnecessary [-Wprofile-instr-out-of-date]
> warnings during profile-use runs even if the source has never been
> modified since profile collection.
>
> http://reviews.llvm.org/D9861
>
> Files:
>   lib/CodeGen/CGClass.cpp
>   test/Profile/cxx-virtual-destructor-calls.cpp
>
> Index: lib/CodeGen/CGClass.cpp
> ===================================================================
> --- lib/CodeGen/CGClass.cpp
> +++ lib/CodeGen/CGClass.cpp
> @@ -1366,6 +1366,10 @@
>    const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
>    CXXDtorType DtorType = CurGD.getDtorType();
>  
> +  Stmt *Body = Dtor->getBody();
> +  if (Body)
> +    incrementProfileCounter(Body);
> +

I think it makes more sense to do this after the delegation and entering
the try body, like we do in constructors, no?

>    // The call to operator delete in a deleting destructor happens
>    // outside of the function-try-block, which means it's always
>    // possible to delegate the destructor body to the complete
> @@ -1378,8 +1382,6 @@
>      return;
>    }
>  
> -  Stmt *Body = Dtor->getBody();
> -
>    // If the body is a function-try-block, enter the try before
>    // anything else.
>    bool isTryBody = (Body && isa<CXXTryStmt>(Body));
> @@ -1389,11 +1391,10 @@
>  
>    // Enter the epilogue cleanups.
>    RunCleanupsScope DtorEpilogue(*this);
> -  
>    // If this is the complete variant, just invoke the base variant;
>    // the epilogue will destruct the virtual bases.  But we can't do
>    // this optimization if the body is a function-try-block, because
> -  // we'd introduce *two* handler blocks.  In the Microsoft ABI, we 
> +  // we'd introduce *two* handler blocks.  In the Microsoft ABI, we
>    // always delegate because we might not have a definition in this TU.
>    switch (DtorType) {
>    case Dtor_Comdat:
> @@ -1414,12 +1415,9 @@
>        break;
>      }
>      // Fallthrough: act like we're in the base variant.
> -      
>    case Dtor_Base:
>      assert(Body);
>  
> -    incrementProfileCounter(Body);
> -
>      // Enter the cleanup scopes for fields and non-virtual bases.
>      EnterDtorCleanups(Dtor, Dtor_Base);
>  
> Index: test/Profile/cxx-virtual-destructor-calls.cpp
> ===================================================================
> --- /dev/null
> +++ test/Profile/cxx-virtual-destructor-calls.cpp
> @@ -0,0 +1,31 @@
> +// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9.0 -emit-llvm -main-file-name cxx-virtual-destructor-calls.cpp %s -o - -fprofile-instr-generate | FileCheck %s
> +
> +struct Member {
> +  ~Member();
> +};
> +
> +struct A {
> +  virtual ~A();
> +};
> +
> +struct B : A {
> +  Member m;
> +  virtual ~B();
> +};
> +
> +// Complete dtor
> +// CHECK: @__llvm_profile_name__ZN1BD1Ev = private constant [9 x i8] c"_ZN1BD1Ev", section "__DATA,__llvm_prf_names", align 1
> +
> +// Deleting dtor
> +// CHECK: @__llvm_profile_name__ZN1BD0Ev = private constant [9 x i8] c"_ZN1BD0Ev", section "__DATA,__llvm_prf_names", align 1
> +
> +// Complete dtor counters and profile data
> +// CHECK: @__llvm_profile_counters__ZN1BD1Ev = private global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
> +// CHECK: @__llvm_profile_data__ZN1BD1Ev =
> +
> +// Deleting dtor counters and profile data
> +// CHECK: @__llvm_profile_counters__ZN1BD0Ev = private global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
> +// CHECK: @__llvm_profile_data__ZN1BD0Ev =
> +
> +B::~B() { }
> +
>
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