From 9415a79dffd77501d2c25be4ee4da71d0f6c335c Mon Sep 17 00:00:00 2001
From: Tim Besard <tim.besard@gmail.com>
Date: Thu, 24 Sep 2026 18:41:21 +0200
Subject: [PATCH] Expand Julia's atomic modify pseudo-intrinsic.

From Julia 1.13, codegen emits atomic modifications (e.g. `@atomic x.f += 1`)
as calls to `julia.atomicmodify`, which Julia's pipeline expands after GC
lowering with `ExpandAtomicModifyPass` (JuliaLang/julia#57010). Our
pipeline didn't, so the call survived and failed validation as a call to
an unknown function.
---
 src/optim.jl   |  6 ++++++
 test/native.jl | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/optim.jl b/src/optim.jl
index 932f316bf..3c1d64087 100644
--- a/src/optim.jl
+++ b/src/optim.jl
@@ -365,6 +365,12 @@ function buildIntrinsicLoweringPipeline(mpm, @nospecialize(job::CompilerJob), op
         if uses_julia_runtime(job) && VERSION >= v"1.11.0-DEV.208"
             add!(fpm, FinalLowerGCPass())
         end
+        # codegen emits atomic modifications (e.g. `@atomic x.f += 1`) as calls to the
+        # `julia.atomicmodify` pseudo-intrinsic, which Julia expands after GC lowering
+        # (JuliaLang/julia#57010)
+        @static if VERSION >= v"1.13.0-DEV.321"
+            add!(fpm, ExpandAtomicModifyPass())
+        end
     end
     if uses_julia_runtime(job) && VERSION < v"1.11.0-DEV.208"
         add!(mpm, FinalLowerGCPass())
diff --git a/test/native.jl b/test/native.jl
index 9b2a61b3b..b5323661d 100644
--- a/test/native.jl
+++ b/test/native.jl
@@ -765,6 +765,25 @@ end
     end
 end
 
+@testset "atomic field modifications" begin
+    # from Julia 1.13, `@atomic x.f += 1` is a call to the `julia.atomicmodify`
+    # pseudo-intrinsic, which has to be expanded (JuliaLang/julia#57010)
+    mod = @eval module $(gensym())
+        mutable struct Counter
+            @atomic n::Int
+        end
+        function increment(c::Counter)
+            @atomic c.n += 1
+            return
+        end
+    end
+
+    @test @filecheck implicit_check_not=["julia.atomicmodify"] begin
+        @check "{{atomicrmw add|cmpxchg}}"
+        Native.code_llvm(mod.increment, Tuple{mod.Counter})
+    end
+end
+
 @testset "tracked pointers" begin
     mod = @eval module $(gensym())
         function kernel(a)