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From 8f83e2b7618da7a98a30839a8f41a6dd82dec468 Mon Sep 17 00:00:00 2001
From: Naveen Saini <naveen.kumar.saini@intel.com>
Date: Fri, 27 Aug 2021 12:00:23 +0800
Subject: [PATCH 1/2] This patch is required to fix stability problem #1793
It's backport of the following llvm 11.0 commit: 120c5f1057dc50229f73bc75bbabf4df6ee50fef
Upstream-Status: Backport
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 2476fd26f250..2743acc89bca 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10702,8 +10702,9 @@ SDValue DAGCombiner::visitSIGN_EXTEND_VECTOR_INREG(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
+ // zext_vector_inreg(undef) = 0 because the top bits will be zero.
if (N0.isUndef())
- return DAG.getUNDEF(VT);
+ return DAG.getConstant(0, SDLoc(N), VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
@@ -10718,8 +10719,9 @@ SDValue DAGCombiner::visitZERO_EXTEND_VECTOR_INREG(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
+ // sext_vector_inreg(undef) = 0 because the top bit will all be the same.
if (N0.isUndef())
- return DAG.getUNDEF(VT);
+ return DAG.getConstant(0, SDLoc(N), VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
--
2.17.1
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