d1fd72343c
The idea is that the CC1 default for ELF should set dso_local on default
visibility external linkage definitions in the default -mrelocation-model pic
mode (-fpic/-fPIC) to match COFF/Mach-O and make output IR similar.
The refactoring is made available by 2820a2ca3a.
Currently only x86 supports local aliases. We move the decision to the driver.
There are three CC1 states:
* -fsemantic-interposition: make some linkages interposable and make default visibility external linkage definitions dso_preemptable.
* (default): selected if the target supports .Lfoo$local: make default visibility external linkage definitions dso_local
* -fhalf-no-semantic-interposition: if neither option is set or the target does not support .Lfoo$local: like -fno-semantic-interposition but local aliases are not used. So references can be interposed if not optimized out.
Add -fhalf-no-semantic-interposition to a few tests using the half-based semantic interposition behavior.
44 lines
2.3 KiB
C++
44 lines
2.3 KiB
C++
// Cross comdat example
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// Parent VTable is in a comdat section.
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// RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O1 -S -o - -emit-llvm -fexperimental-relative-c++-abi-vtables -fhalf-no-semantic-interposition | FileCheck %s
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// The inline function is emitted in each module with the same comdat
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// CHECK: $_ZTS1A = comdat any
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// CHECK: $_ZTI1A = comdat any
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// CHECK: $_ZTI1B.rtti_proxy = comdat any
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// The VTable is emitted everywhere used
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// CHECK: $_ZTV1A = comdat any
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// CHECK: $_ZTI1A.rtti_proxy = comdat any
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// The VTable for B is emitted here since it has a key function which is defined in this module
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// CHECK: @_ZTV1B.local = private unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint ({ i8*, i8*, i8* }** @_ZTI1B.rtti_proxy to i64), i64 ptrtoint (i32* getelementptr inbounds ({ [3 x i32] }, { [3 x i32] }* @_ZTV1B.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (void (%class.B*)* dso_local_equivalent @_ZN1B3fooEv to i64), i64 ptrtoint (i32* getelementptr inbounds ({ [3 x i32] }, { [3 x i32] }* @_ZTV1B.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, align 4
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// The VTable for A is emitted here and in a comdat section since it has no key function, and is used in this module when creating an instance of A (in func()).
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// CHECK: @_ZTV1A.local = linkonce_odr hidden unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint ({ i8*, i8* }** @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (i32* getelementptr inbounds ({ [3 x i32] }, { [3 x i32] }* @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (void (%class.A*)* dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (i32* getelementptr inbounds ({ [3 x i32] }, { [3 x i32] }* @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, comdat($_ZTV1A), align 4
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// CHECK: @_ZTV1B ={{.*}} unnamed_addr alias { [3 x i32] }, { [3 x i32] }* @_ZTV1B.local
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// CHECK: @_ZTV1A = linkonce_odr unnamed_addr alias { [3 x i32] }, { [3 x i32] }* @_ZTV1A.local
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// CHECK: define{{.*}} void @_ZN1B3fooEv(%class.B* {{.*}}%this) unnamed_addr
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// CHECK-NEXT: entry:
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// CHECK-NEXT: ret void
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// CHECK-NEXT: }
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class A {
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public:
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inline virtual void foo() {}
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};
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class B : public A {
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public:
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void foo() override;
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};
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void A_foo(A *a);
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void B::foo() {}
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void func2() {
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A a;
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A_foo(&a);
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}
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