From 91f62324d4c054035a1bccee63c38c2cdeb2cf8d Mon Sep 17 00:00:00 2001
From: "Hans J. Johnson" <hans-johnson@uiowa.edu>
Date: Tue, 28 Apr 2026 21:18:54 -0500
Subject: [PATCH] COMP: Use pzero(Packet{}) for SelfadjointMatrixVector
 accumulators

GCC -O3 IPA-CP emits false-positive -Wmaybe-uninitialized on the
cloned `selfadjoint_matrix_vector_product::run.constprop.isra`:
`pset1<Packet>(Scalar(0))` is opaque to interprocedural constant
propagation, while `pzero(Packet{})` (used by upstream Eigen master)
is visible as a constant. Backport just the ptmp2/ptmp3 init lines.
---
 .../Eigen/src/Core/products/SelfadjointMatrixVector.h         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h b/Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h
index 1b74a1d24fea..6e3c0dc6fe08 100644
--- a/Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h
+++ b/Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h
@@ -81,9 +81,9 @@ selfadjoint_matrix_vector_product<Scalar, Index, StorageOrder, UpLo, ConjugateLh
     Packet ptmp1 = pset1<Packet>(t1);
 
     Scalar t2(0);
-    Packet ptmp2 = pset1<Packet>(t2);
+    Packet ptmp2 = pzero(Packet{});
     Scalar t3(0);
-    Packet ptmp3 = pset1<Packet>(t3);
+    Packet ptmp3 = pzero(Packet{});
 
     Index starti = FirstTriangular ? 0 : j + 2;
     Index endi = FirstTriangular ? j : size;