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[clang][Fuchsia] Have global dtors use llvm.global_dtors over atexit #115788

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[clang][Fuchsia] Have global dtors use llvm.global_dtors over atexit #115788

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8 changes: 8 additions & 0 deletions clang/lib/CodeGen/ItaniumCXXABI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -518,6 +518,14 @@ class FuchsiaCXXABI final : public ItaniumCXXABI {
explicit FuchsiaCXXABI(CodeGen::CodeGenModule &CGM)
: ItaniumCXXABI(CGM) {}

// Rather than using the defaul [__cxa_]atexit, instead use llvm.global_dtors
// which will result in .fini_array being used.
void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
llvm::FunctionCallee dtor,
llvm::Constant *addr) override {
return CGM.AddCXXDtorEntry(dtor, addr);
}

private:
bool constructorsAndDestructorsReturnThis() const override { return true; }
};
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25 changes: 25 additions & 0 deletions clang/test/CodeGenCXX/fuchsia-global-dtor.cpp
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@@ -0,0 +1,25 @@
/// Global destructors targetting Fuchsia should not use [__cxa_]atexit. Instead
/// they should be invoked through llvm.global_dtors.

// RUN: %clang_cc1 %s -triple aarch64-unknown-fuchsia -emit-llvm -o - | FileCheck %s

// CHECK-NOT: atexit

// CHECK: @llvm.global_dtors = appending global [1 x { i32, ptr, ptr }]
// CHECK-SAME: [{ i32, ptr, ptr } { i32 {{.*}}, ptr [[MODULE_DTOR:@.*]], ptr {{.*}} }]

// CHECK: define internal void [[MODULE_DTOR]]() {{.*}}{
// CHECK-NEXT: entry:
// CHECK-NEXT: %0 = call ptr @_ZN1AD1Ev(ptr @DestroyFirst)
// CHECK-NEXT: %1 = call ptr @_ZN1AD1Ev(ptr @DestroySecond)
// CHECK-NEXT: %2 = call ptr @_ZN1AD1Ev(ptr @DestroyThird)
// CHECK-NEXT: ret void
// CHECK-NEXT: }

struct A {
~A() {}
};

A DestroyThird;
A DestroySecond;
A DestroyFirst;
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