[llvm] [LLVM][CodeGen] When expanding ISD::LRINT, non-deterministic results should be frozen. (PR #197435)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm created https://github.com/llvm/llvm-project/pull/197435

This comes from https://github.com/llvm/llvm-project/pull/194342#discussion_r3155677450.

>From 1a8ceee529f8d6ec9dc62bdbe6fb1675d676286c Mon Sep 17 00:00:00 2001
From: Paul Walker <paul.walker at arm.com>
Date: Wed, 13 May 2026 13:10:39 +0000
Subject: [PATCH] [LLVM][CodeGen] When expanding ISD::LRINT non-deterministic
 results should be frozen.

---
 llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 9e4f169cd4f3f..dca1a0b58c16a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -4636,9 +4636,11 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     SDValue Arg = Node->getOperand(0);
     EVT ArgVT = Arg.getValueType();
     EVT ResVT = Node->getValueType(0);
-    SDLoc dl(Node);
-    SDValue RoundNode = DAG.getNode(ISD::FRINT, dl, ArgVT, Arg);
-    Results.push_back(DAG.getNode(ISD::FP_TO_SINT, dl, ResVT, RoundNode));
+    SDLoc DL(Node);
+    SDValue RoundNode = DAG.getNode(ISD::FRINT, DL, ArgVT, Arg);
+    SDValue ConvertNode = DAG.getNode(ISD::FP_TO_SINT, DL, ResVT, RoundNode);
+    // Non-deterministic results are equivalent to freeze poison.
+    Results.push_back(DAG.getFreeze(ConvertNode));
     break;
   }
   case ISD::ADDRSPACECAST: