[llvm] 9fa7627 - DAG: Handle poison in m_Undef (#168288)

[via llvm-commits]

Author: Matt Arsenault
Date: 2025-11-21T18:29:15-05:00
New Revision: 9fa7627d891007e495eb701a30c09761403f8042

URL: https://github.com/llvm/llvm-project/commit/9fa7627d891007e495eb701a30c09761403f8042
DIFF: https://github.com/llvm/llvm-project/commit/9fa7627d891007e495eb701a30c09761403f8042.diff

LOG: DAG: Handle poison in m_Undef (#168288)

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/SDPatternMatch.h
    llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/SDPatternMatch.h b/llvm/include/llvm/CodeGen/SDPatternMatch.h
index a81b91e338cb8..f7851fed57b32 100644
--- a/llvm/include/llvm/CodeGen/SDPatternMatch.h
+++ b/llvm/include/llvm/CodeGen/SDPatternMatch.h
@@ -222,7 +222,9 @@ template <typename... Preds> auto m_NoneOf(const Preds &...preds) {
 
 inline Opcode_match m_Opc(unsigned Opcode) { return Opcode_match(Opcode); }
 
-inline Opcode_match m_Undef() { return Opcode_match(ISD::UNDEF); }
+inline auto m_Undef() {
+  return m_AnyOf(Opcode_match(ISD::UNDEF), Opcode_match(ISD::POISON));
+}
 
 inline Opcode_match m_Poison() { return Opcode_match(ISD::POISON); }
 

diff  --git a/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp b/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
index ceaee52a3948b..d7f2749ee493a 100644
--- a/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
+++ b/llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
@@ -551,6 +551,8 @@ TEST_F(SelectionDAGPatternMatchTest, matchConstants) {
   SDValue PoisonVInt32VT = DAG->getPOISON(VInt32VT);
   EXPECT_TRUE(sd_match(PoisonInt32VT, m_Poison()));
   EXPECT_TRUE(sd_match(PoisonVInt32VT, m_Poison()));
+  EXPECT_TRUE(sd_match(PoisonInt32VT, m_Undef()));
+  EXPECT_TRUE(sd_match(PoisonVInt32VT, m_Undef()));
 }
 
 TEST_F(SelectionDAGPatternMatchTest, patternCombinators) {