[clang] 3b34d69 - Revert "For #64088: mark vtable as used if we might emit a reference to it."

[Richard Smith via cfe-commits]

This revert reintroduces a wrong-code bug, can you explain what the purpose
of the revert is?

On Fri, 28 Jul 2023 at 03:50, Dmitry Chernenkov via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

>
> Author: Dmitry Chernenkov
> Date: 2023-07-28T10:49:53Z
> New Revision: 3b34d69ac7a643742364be3591b324ddd14ef9aa
>
> URL:
> https://github.com/llvm/llvm-project/commit/3b34d69ac7a643742364be3591b324ddd14ef9aa
> DIFF:
> https://github.com/llvm/llvm-project/commit/3b34d69ac7a643742364be3591b324ddd14ef9aa.diff
>
> LOG: Revert "For #64088: mark vtable as used if we might emit a reference
> to it."
>
> This reverts commit b6847edfc235829b37dd6d734ef5bbfa0a58b6fc.
>
> Added:
>
>
> Modified:
>     clang/lib/Sema/SemaCast.cpp
>     clang/test/CodeGenCXX/dynamic-cast-exact.cpp
>
> Removed:
>
>
>
>
> ################################################################################
> diff  --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp
> index b338d601db7397..d65ecf52c52310 100644
> --- a/clang/lib/Sema/SemaCast.cpp
> +++ b/clang/lib/Sema/SemaCast.cpp
> @@ -935,14 +935,6 @@ void CastOperation::CheckDynamicCast() {
>            << isClangCL;
>    }
>
> -  // For a dynamic_cast to a final type, IR generation might emit a
> reference
> -  // to the vtable.
> -  if (DestRecord) {
> -    auto *DestDecl = DestRecord->getAsCXXRecordDecl();
> -    if (DestDecl->isEffectivelyFinal())
> -      Self.MarkVTableUsed(OpRange.getBegin(), DestDecl);
> -  }
> -
>    // Done. Everything else is run-time checks.
>    Kind = CK_Dynamic;
>  }
>
> diff  --git a/clang/test/CodeGenCXX/dynamic-cast-exact.cpp
> b/clang/test/CodeGenCXX/dynamic-cast-exact.cpp
> index bd283e85101b4b..676aa975a72686 100644
> --- a/clang/test/CodeGenCXX/dynamic-cast-exact.cpp
> +++ b/clang/test/CodeGenCXX/dynamic-cast-exact.cpp
> @@ -76,12 +76,3 @@ H *exact_multi(A *a) {
>    // CHECK: phi ptr [ %[[RESULT]], %[[LABEL_NOTNULL]] ], [ null,
> %[[LABEL_FAILED]] ]
>    return dynamic_cast<H*>(a);
>  }
> -
> -namespace GH64088 {
> -  // Ensure we mark the B vtable as used here, because we're going to
> emit a
> -  // reference to it.
> -  // CHECK: define {{.*}} @_ZN7GH640881BD0
> -  struct A { virtual ~A(); };
> -  struct B final : A { virtual ~B() = default; };
> -  B *cast(A *p) { return dynamic_cast<B*>(p); }
> -}
>
>
>
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