From 61df7cc8b91365e487591ec8402e797a25790a79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Manuel=20H=C3=A4ssig?= <mhaessig@openjdk.org>
Date: Mon, 30 Mar 2026 06:27:30 +0000
Subject: [PATCH] 8380988: C2: Unexpected node in SuperWord truncation:
 UModI/UDivI

Reviewed-by: epeter, jkarthikeyan
---
 src/hotspot/share/opto/superword.cpp          |  2 +
 .../vectorization/TestSubwordTruncation.java  | 46 ++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/hotspot/share/opto/superword.cpp b/src/hotspot/share/opto/superword.cpp
index d878b2b1d3d..53845a94c1c 100644
--- a/src/hotspot/share/opto/superword.cpp
+++ b/src/hotspot/share/opto/superword.cpp
@@ -2500,7 +2500,9 @@ static bool can_subword_truncate(Node* in, const Type* type) {
   switch (opc) {
   case Op_AbsI:
   case Op_DivI:
+  case Op_UDivI:
   case Op_ModI:
+  case Op_UModI:
   case Op_MinI:
   case Op_MaxI:
   case Op_CMoveI:
diff --git a/test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java b/test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java
index 2f6296e41d2..0a80a59efd4 100644
--- a/test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java
+++ b/test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java
@@ -29,7 +29,7 @@ import compiler.lib.generators.*;
 
 /*
  * @test
- * @bug 8350177 8362171 8369881 8342095
+ * @bug 8350177 8362171 8369881 8342095 8380988
  * @summary Ensure that truncation of subword vectors produces correct results
  * @library /test/lib /
  * @run driver compiler.vectorization.TestSubwordTruncation
@@ -448,6 +448,50 @@ public class TestSubwordTruncation {
         }
     }
 
+    @Test
+    @IR(counts = { IRNode.UMOD_I, ">0" })
+    @Arguments(setup = "setupByteArray")
+    public Object[] testUMod(final byte[] in) {
+        int n = G.next().intValue();
+        for (int i = 1; i < SIZE; i++) {
+            in[i] = (byte) Integer.remainderUnsigned(n, i);
+        }
+
+        return new Object[] { Integer.valueOf(n), in };
+    }
+
+    @Check(test = "testUMod")
+    public void checkTestUMod(Object[] vals) {
+        int n = (Integer) vals[0];
+        byte[] res = (byte[]) vals[1];
+        for (int i = 1; i < SIZE; i++) {
+            byte val = (byte) Integer.remainderUnsigned(n, i);
+            Asserts.assertEQ(res[i], val);
+        }
+    }
+
+    @Test
+    @IR(counts = { IRNode.UDIV_I, ">0" })
+    @Arguments(setup = "setupByteArray")
+    public Object[] testUDiv(final byte[] in) {
+        int n = G.next().intValue();
+        for (int i = 1; i < SIZE; i++) {
+            in[i] = (byte) Integer.divideUnsigned(n, i);
+        }
+
+        return new Object[] { Integer.valueOf(n), in };
+    }
+
+    @Check(test = "testUDiv")
+    public void checkTestUDiv(Object[] vals) {
+        int n = (Integer) vals[0];
+        byte[] res = (byte[]) vals[1];
+        for (int i = 1; i < SIZE; i++) {
+            byte val = (byte) Integer.divideUnsigned(n, i);
+            Asserts.assertEQ(res[i], val);
+        }
+    }
+
     @Test
     @IR(counts = { IRNode.CMP_LT_MASK, ">0" })
     @Arguments(setup = "setupByteArray")