From 8f05136256d9c9a3fd4b0543fe4e6088cc4f3a38 Mon Sep 17 00:00:00 2001
From: Valentin Churavy <v.churavy@gmail.com>
Date: Sat, 30 Nov 2024 14:44:23 +0100
Subject: [PATCH 1/4] Add test for Zero-sized types

---
 test/runtests.jl | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test/runtests.jl b/test/runtests.jl
index 9ee4bfe..c0556cd 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -10,6 +10,10 @@ function check_default_ordering(T::Type)
     xs = T[rand(T), rand(T)]
     x1 = rand(T)
     x2 = rand(T)
+    check_default_ordering(xs, x1, x2)
+end
+
+function check_default_ordering(xs::AbstractArray{T}, x1::T, x2::T,) where T
     @debug "xs=$(repr(xs)) x1=$(repr(x1)) x2=$(repr(x2))"
 
     ptr = llvmptr(xs, 1)
@@ -17,6 +21,7 @@ function check_default_ordering(T::Type)
         @test UnsafeAtomics.load(ptr) === xs[1]
         UnsafeAtomics.store!(ptr, x1)
         @test xs[1] === x1
+        sizeof(T) == 0 && return # CAS hangs on zero sized data...
         desired = (old = x1, success = true)
         @test UnsafeAtomics.cas!(ptr, x1, x2) === (old = x1, success = true)
         @test xs[1] === x2
@@ -37,6 +42,10 @@ function test_explicit_ordering(T::Type = UInt)
     xs = T[rand(T), rand(T)]
     x1 = rand(T)
     x2 = rand(T)
+    test_explicit_ordering(xs, x1, x2)
+end
+
+function test_explicit_ordering(xs::AbstractArray{T}, x1::T, x2::T,) where T
     @debug "xs=$(repr(xs)) x1=$(repr(x1)) x2=$(repr(x2))"
 
     ptr = llvmptr(xs, 1)
@@ -45,6 +54,7 @@ function test_explicit_ordering(T::Type = UInt)
         @test UnsafeAtomics.load(ptr, acquire) === xs[1]
         UnsafeAtomics.store!(ptr, x1, release)
         @test xs[1] === x1
+        sizeof(T) == 0 && return # CAS hangs on zero sized data...
         desired = (old = x1, success = true)
         @test UnsafeAtomics.cas!(ptr, x1, x2, acq_rel, acquire) === desired
         @test xs[1] === x2
@@ -79,4 +89,10 @@ end
         check_default_ordering(T)
         test_explicit_ordering(T)
     end
+
+    @testset "Zero-sized types" begin
+        @test sizeof(Nothing) == 0
+        check_default_ordering([nothing, nothing], nothing, nothing)
+        test_explicit_ordering([nothing, nothing], nothing, nothing)
+    end
 end

From 2cbcfe99e5b2067302499f3edce45f58cf155919 Mon Sep 17 00:00:00 2001
From: Valentin Churavy <v.churavy@gmail.com>
Date: Sat, 30 Nov 2024 14:47:41 +0100
Subject: [PATCH 2/4] Fix fence usage

---
 src/atomics.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/atomics.jl b/src/atomics.jl
index 9b1e504..6a9c8f2 100644
--- a/src/atomics.jl
+++ b/src/atomics.jl
@@ -191,9 +191,9 @@ end
     if sizeof(T) == 0
         # Mimicking what `Core.Intrinsics.atomic_pointerset` generates.
         # See: https://github.com/JuliaLang/julia/blob/v1.7.2/src/cgutils.cpp#L1570-L1572
-        is_stronger_than_monotonic(order) || return :ptr
         return quote
-            Core.Intrinsics.fence($(QuoteNode(order)))
+            is_stronger_than_monotonic(_valueof(order)) || return :ptr
+            Core.Intrinsics.atomic_fence(_valueof(order))
             ptr
         end
     end

From a4143650e2e8975a06fc9d5f97e8d55b3d08e43e Mon Sep 17 00:00:00 2001
From: Valentin Churavy <v.churavy@gmail.com>
Date: Sat, 30 Nov 2024 14:48:12 +0100
Subject: [PATCH 3/4] Bump package version

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 5c4191f..1a8a8f6 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "UnsafeAtomicsLLVM"
 uuid = "d80eeb9a-aca5-4d75-85e5-170c8b632249"
 authors = ["Takafumi Arakaki <aka.tkf@gmail.com> and contributors"]
-version = "0.2.1"
+version = "0.2.2"
 
 [deps]
 LLVM = "929cbde3-209d-540e-8aea-75f648917ca0"

From f890dcc57c059ad37e50489e5a1850dc3e25389f Mon Sep 17 00:00:00 2001
From: Valentin Churavy <vchuravy@users.noreply.github.com>
Date: Sat, 30 Nov 2024 14:50:47 +0100
Subject: [PATCH 4/4] Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 test/runtests.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index c0556cd..da5139a 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -13,7 +13,7 @@ function check_default_ordering(T::Type)
     check_default_ordering(xs, x1, x2)
 end
 
-function check_default_ordering(xs::AbstractArray{T}, x1::T, x2::T,) where T
+function check_default_ordering(xs::AbstractArray{T}, x1::T, x2::T) where {T}
     @debug "xs=$(repr(xs)) x1=$(repr(x1)) x2=$(repr(x2))"
 
     ptr = llvmptr(xs, 1)
@@ -45,7 +45,7 @@ function test_explicit_ordering(T::Type = UInt)
     test_explicit_ordering(xs, x1, x2)
 end
 
-function test_explicit_ordering(xs::AbstractArray{T}, x1::T, x2::T,) where T
+function test_explicit_ordering(xs::AbstractArray{T}, x1::T, x2::T) where {T}
     @debug "xs=$(repr(xs)) x1=$(repr(x1)) x2=$(repr(x2))"
 
     ptr = llvmptr(xs, 1)