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[IRGen] Use linkonce_odr hidden linkage for _swift_dead_method_stub #84836

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Merged
merged 3 commits into from
Oct 14, 2025
Merged

[IRGen] Use linkonce_odr hidden linkage for _swift_dead_method_stub #84836

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7e8f782
[IRGen] Use linkonce_odr hidden linkage for _swift_dead_method_stub
DougGregor Oct 11, 2025
bccfe33
[IRGen] Leave _swift_dead_method_stub Internal for COFF
DougGregor Oct 13, 2025
7668653
Mark two tests as unsupported on Windows for the moment
DougGregor Oct 13, 2025
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13 changes: 10 additions & 3 deletions lib/IRGen/GenDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2191,11 +2191,18 @@ void IRGenModule::emitVTableStubs() {

if (!stub) {
// Create a single stub function which calls swift_deletedMethodError().
// Use linkonce_odr hidden to merge these symbols, except on
// COFF where the linker cannot merge them.
bool canLinkOnce = !Module.getTargetTriple().isOSBinFormatCOFF();
auto linkage = canLinkOnce ? llvm::GlobalValue::LinkOnceODRLinkage
: llvm::GlobalValue::InternalLinkage;
stub = llvm::Function::Create(llvm::FunctionType::get(VoidTy, false),
llvm::GlobalValue::InternalLinkage,
"_swift_dead_method_stub");
linkage, "_swift_dead_method_stub",
&Module);
ApplyIRLinkage(canLinkOnce ? IRLinkage::InternalLinkOnceODR
: IRLinkage::Internal)
.to(stub);
stub->setAttributes(constructInitialAttributes());
Module.getFunctionList().push_back(stub);
stub->setCallingConv(DefaultCC);
auto *entry = llvm::BasicBlock::Create(getLLVMContext(), "entry", stub);
auto *errorFunc = getDeletedMethodErrorFn();
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12 changes: 8 additions & 4 deletions test/IRGen/static-vtable-stubs.swift
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Expand Up @@ -8,19 +8,23 @@

// REQUIRES: concurrency

// Note: Windows uses internal linkage, which puts an extra step symbol before
// _swift_dead_method_stub.
// UNSUPPORTED: OS=windows-msvc

//--- A.swift
open class C {
private var i: [ObjectIdentifier:Any] = [:]

private func foo() async {}
}

// CHECK: @"$s1M1CC3foo33_{{.*}}Tu" = hidden global %swift.async_func_pointer <{ {{.*}} @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvg"
// CHECK: @"$s1M1CC3foo33_{{.*}}Tu" = hidden global %swift.async_func_pointer <{ {{.*}} @_swift_dead_method_stub

// CHECK: @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvs" = hidden alias void (), ptr @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvg"
// CHECK: @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvM" = hidden alias void (), ptr @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvg"
// CHECK: @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvs" = hidden alias void (), ptr @_swift_dead_method_stub
// CHECK: @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvM" = hidden alias void (), ptr @_swift_dead_method_stub

// CHECK: define hidden void @"$s1M1CC1i33_807E3D81CC6CDD898084F3279464DDF9LLSDySOypGvg"()
// CHECK: define {{(linkonce_odr )?}}hidden void @_swift_dead_method_stub()
// CHECK: entry:
// CHECK: tail call void @swift_deletedMethodError()

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8 changes: 6 additions & 2 deletions test/IRGen/zombies.swift
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@@ -1,5 +1,9 @@
// RUN: %target-swift-frontend -primary-file %s -O -emit-ir | %FileCheck %s

// Note: Windows uses internal linkage, which puts an extra step symbol before
// _swift_dead_method_stub.
// UNSUPPORTED: OS=windows-msvc

// rdar://24121475
// Ideally, these wouldn't be in the v-table at all; but as long as they
// are, we need to emit symbols for them.
Expand All @@ -8,8 +12,8 @@ class C {
init(i: Int) { self.i = i }
}

// CHECK: @"$s7zombies1CC1i33_{{.*}}vs" = hidden {{(dllexport )?}}alias void (), ptr @"$s7zombies1CC1i33_45489CBEFBF369AB7AEE3A799A95D78DLLSivg"
// CHECK: @"$s7zombies1CC1i33_{{.*}}vs" = hidden {{(dllexport )?}}alias void (), ptr @_swift_dead_method_stub

// CHECK: define hidden void @"$s7zombies1CC1i33_45489CBEFBF369AB7AEE3A799A95D78DLLSivg"()
// CHECK: define {{(linkonce_odr )?}}hidden void @_swift_dead_method_stub
// CHECK: entry:
// CHECK: tail call void @swift_deletedMethodError()
7 changes: 6 additions & 1 deletion test/embedded/linkage/leaf_application.swift
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Expand Up @@ -56,13 +56,15 @@ public func unnecessary() -> Int64 { 5 }
@_neverEmitIntoClient
public func unusedYetThere() -> Int64 { 5 }

public class PointClass {
open class PointClass {
public var x, y: Int

public init(x: Int, y: Int) {
self.x = x
self.y = y
}

private func notUsed() { }
}

public protocol Reflectable: AnyObject {
Expand All @@ -89,6 +91,9 @@ public func createsExistential() -> any Reflectable {

// LIBRARY-IR-NOT: define {{.*}} @"$es27_allocateUninitializedArrayySayxG_BptBwlFSi_Tg5"


// LIBRARY-IR: define linkonce_odr hidden void @_swift_dead_method_stub

// LIBRARY-SIL: sil @$e7Library5helloSaySiGyF
// LIBRARY-SIL: sil @$e7Library8getArraySaySiGyF : $@convention(thin) () -> @owned Array<Int> {

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