0371dff995
When using the relative vtable ABI, if a vtable is not dso_local, it's given private linkage (if not COMDAT) or hidden visibility (if COMDAT) to make it dso_local (to place it in rodata instead of data.rel.ro), and an alias generated with the original linkage and visibility. This alias could later be removed from the symbol table, e.g. if using a version script, at which point we lose all symbol information about the vtable. Use internal linkage instead of private linkage to avoid this. While I'm here, clarify the comment about why COMDAT vtables can't use internal (or private) linkage, and associate it with the else block where hidden visibility is applied instead of internal linkage.
32 lines
1.5 KiB
C++
32 lines
1.5 KiB
C++
// Check the layout of the vtable for a normal class.
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// RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O1 -o - -emit-llvm -fhalf-no-semantic-interposition | FileCheck %s
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// We should be emitting comdats for each of the virtual function RTTI proxies
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// CHECK: $_ZTI1A.rtti_proxy = comdat any
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// VTable contains offsets and references to the hidden symbols
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// The vtable definition itself is private so we can take relative references to
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// it. The vtable symbol will be exposed through a public alias.
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// CHECK: @_ZTV1A.local = internal unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, align 4
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// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
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// CHECK: @_ZTS1A ={{.*}} constant [3 x i8] c"1A\00", align 1
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// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
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// The rtti should be in a comdat
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// CHECK: @_ZTI1A.rtti_proxy = {{.*}}comdat
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// The vtable symbol is exposed through an alias.
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// @_ZTV1A = dso_local unnamed_addr alias { [3 x i32] }, ptr @_ZTV1A.local
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class A {
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public:
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virtual void foo();
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};
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void A::foo() {}
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void A_foo(A *a) {
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a->foo();
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}
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