From ac3344d0a24e0812107cc844c579b32cc0acb586 Mon Sep 17 00:00:00 2001
From: Hendrik Ranocha <mail@ranocha.de>
Date: Fri, 28 Nov 2025 09:12:55 +0100
Subject: [PATCH] add new test for issue 543

---
 test/staticsize.jl | 64 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/test/staticsize.jl b/test/staticsize.jl
index 6ff2b0f6..5d14e956 100644
--- a/test/staticsize.jl
+++ b/test/staticsize.jl
@@ -135,3 +135,67 @@ end
     @test sum2_10turbo(A) ≈ sum(A)
   end
 end
+
+# Test for Issue #543: W=1 nested VecUnroll store on ARM
+# This tests the case where vector width is 1 (scalar) with nested unrolling
+function issue543_noavx!(data_out, matrix, data_in)
+  for j in axes(data_out, 3), i in axes(data_out, 2), v in axes(data_out, 1)
+    res = zero(eltype(data_out))
+    for jj in axes(matrix, 2)
+      res += matrix[j, jj] * data_in[v, i, jj]
+    end
+    data_out[v, i, j] = res
+  end
+  return nothing
+end
+
+function issue543_turbo!(data_out, matrix, data_in)
+  @turbo for j in axes(data_out, 3), i in axes(data_out, 2), v in axes(data_out, 1)
+    res = zero(eltype(data_out))
+    for jj in axes(matrix, 2)
+      res += matrix[j, jj] * data_in[v, i, jj]
+    end
+    data_out[v, i, j] = res
+  end
+  return nothing
+end
+
+@testset "Issue #543: W=1 Nested VecUnroll" begin
+  # Test the specific case that was failing: v=1 (first dim size 1) with n=5
+  # This triggers W=1 code paths where VecUnroll stores T instead of Vec{1,T}
+  for v in [1, 2], n in [4, 5, 6, 7, 8]
+    data_out_ref = StrideArray(undef, StaticInt(v), StaticInt(n), StaticInt(n))
+    data_out_turbo = StrideArray(undef, StaticInt(v), StaticInt(n), StaticInt(n))
+    matrix = StrideArray(undef, StaticInt(n), StaticInt(n))
+    data_in = rand(v, n, n)
+
+    # Initialize with random data
+    matrix .= rand.()
+
+    fill!(data_out_ref, 0.0)
+    fill!(data_out_turbo, 0.0)
+
+    issue543_noavx!(data_out_ref, matrix, data_in)
+    issue543_turbo!(data_out_turbo, matrix, data_in)
+
+    @test data_out_turbo ≈ data_out_ref
+  end
+
+  # Also test with non-static first dimension but static others
+  for v in [1, 2], n in [4, 5, 6]
+    data_out_ref = StrideArray(undef, v, StaticInt(n), StaticInt(n))
+    data_out_turbo = StrideArray(undef, v, StaticInt(n), StaticInt(n))
+    matrix = StrideArray(undef, StaticInt(n), StaticInt(n))
+    data_in = rand(v, n, n)
+
+    matrix .= rand.()
+
+    fill!(data_out_ref, 0.0)
+    fill!(data_out_turbo, 0.0)
+
+    issue543_noavx!(data_out_ref, matrix, data_in)
+    issue543_turbo!(data_out_turbo, matrix, data_in)
+
+    @test data_out_turbo ≈ data_out_ref
+  end
+end