From c858e99116d420fcc9e0e3292b65e011eb6651c2 Mon Sep 17 00:00:00 2001
From: Martien de Jong <martien.de-jong@xilinx.com>
Date: Wed, 9 Oct 2024 12:17:53 +0200
Subject: [PATCH] [AIE] Fix PostPipeliner crash

We can't check LCDs for NCopies=1, but it also never gives a useful schedule.
---
 llvm/lib/Target/AIE/AIEPostPipeliner.cpp | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/AIE/AIEPostPipeliner.cpp b/llvm/lib/Target/AIE/AIEPostPipeliner.cpp
index 950ea4ccfbad..e20b59c57b5f 100644
--- a/llvm/lib/Target/AIE/AIEPostPipeliner.cpp
+++ b/llvm/lib/Target/AIE/AIEPostPipeliner.cpp
@@ -330,15 +330,19 @@ bool PostPipeliner::scheduleOtherIterations() {
 }
 
 bool PostPipeliner::schedule(ScheduleDAGMI &TheDAG, int InitiationInterval) {
+  NTotalInstrs = TheDAG.SUnits.size();
+  assert(NTotalInstrs % NInstr == 0);
+  NCopies = NTotalInstrs / NInstr;
+  if (NCopies == 1) {
+    LLVM_DEBUG(dbgs() << "PostPipeliner: Not feasible\n");
+    return false;
+  }
   II = InitiationInterval;
   DAG = &TheDAG;
-  NTotalInstrs = DAG->SUnits.size();
   FirstUnscheduled = 0;
-  assert(NTotalInstrs % NInstr == 0);
 
   // Let's not skimp on size here. This allows us to insert any instruction
   // in the unrolled dag.
-  NCopies = NTotalInstrs / NInstr;
   Depth = NCopies * II + HR.getPipelineDepth();
   Scoreboard.reset(Depth);