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[embedded] Fix an LLVMARCOpts crash by avoiding direct calls to swift_retain/swift_release #69256

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Merged
merged 2 commits into from
Oct 19, 2023
Merged

[embedded] Fix an LLVMARCOpts crash by avoiding direct calls to swift_retain/swift_release #69256

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6900efe
[embedded] Fix an LLVMARCOpts crash by avoiding direct calls to swift…
kubamracek Oct 18, 2023
719697d
[embedded] Rename and explain test/embedded/ouroboros-bug.swift
kubamracek Oct 19, 2023
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8 changes: 6 additions & 2 deletions stdlib/public/core/EmbeddedRuntime.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -131,7 +131,9 @@ public func swift_isUniquelyReferenced_nonNull_native(object: UnsafeMutablePoint

@_silgen_name("swift_retain")
public func swift_retain(object: Builtin.RawPointer) -> Builtin.RawPointer {
return swift_retain_n(object: object, n: 1)
if Int(Builtin.ptrtoint_Word(object)) == 0 { return object }
let o = UnsafeMutablePointer<HeapObject>(object)
return swift_retain_n_(object: o, n: 1)._rawValue
}

// Cannot use UnsafeMutablePointer<HeapObject>? directly in the function argument or return value as it causes IRGen crashes
Expand All @@ -155,7 +157,9 @@ func swift_retain_n_(object: UnsafeMutablePointer<HeapObject>, n: UInt32) -> Uns

@_silgen_name("swift_release")
public func swift_release(object: Builtin.RawPointer) {
swift_release_n(object: object, n: 1)
if Int(Builtin.ptrtoint_Word(object)) == 0 { return }
let o = UnsafeMutablePointer<HeapObject>(object)
swift_release_n_(object: o, n: 1)
}

@_silgen_name("swift_release_n")
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15 changes: 15 additions & 0 deletions test/embedded/ouroboros-bug.swift
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@@ -0,0 +1,15 @@
// Regression test for a "Ouroboros Bug": The ARC optimizer doesn't like the
// presense of a direct call to swift_retain and swift_release in any Swift
// code, but in the embedded Swift's runtime that's somewhat reasonable thing
// to do (but is to be avoided because of this).

// RUN: %target-swift-frontend -target armv7-apple-none-macho -assert-config Debug -Osize -Xcc -D__MACH__ -emit-ir %s -enable-experimental-feature Embedded | %FileCheck %s
// RUN: %target-swift-frontend -target arm64-apple-none-macho -assert-config Debug -Osize -Xcc -D__MACH__ -Xcc -D__arm64__ -Xcc -D__APPLE__ -emit-ir %s -enable-experimental-feature Embedded | %FileCheck %s

// REQUIRES: VENDOR=apple
// REQUIRES: optimized_stdlib

public func test() {}
test()

// CHECK: define {{.*}}i32 @main