From 76cb876563d0e2a3c850b14ca68638be9f6124a0 Mon Sep 17 00:00:00 2001
From: Arjun P <arjunpitchanathan@gmail.com>
Date: Mon, 20 Sep 2021 13:09:05 +0530
Subject: [PATCH] [MLIR] Simplex::appendVariable: early return if count == 0

---
 mlir/lib/Analysis/Presburger/Simplex.cpp           | 2 ++
 mlir/unittests/Analysis/Presburger/SimplexTest.cpp | 1 +
 2 files changed, 3 insertions(+)

diff --git a/mlir/lib/Analysis/Presburger/Simplex.cpp b/mlir/lib/Analysis/Presburger/Simplex.cpp
index d97a46f2b811..26b4c60e3139 100644
--- a/mlir/lib/Analysis/Presburger/Simplex.cpp
+++ b/mlir/lib/Analysis/Presburger/Simplex.cpp
@@ -483,6 +483,8 @@ void Simplex::rollback(unsigned snapshot) {
 }
 
 void Simplex::appendVariable(unsigned count) {
+  if (count == 0)
+    return;
   var.reserve(var.size() + count);
   colUnknown.reserve(colUnknown.size() + count);
   for (unsigned i = 0; i < count; ++i) {
diff --git a/mlir/unittests/Analysis/Presburger/SimplexTest.cpp b/mlir/unittests/Analysis/Presburger/SimplexTest.cpp
index d1bb6499c315..2f1ce819c672 100644
--- a/mlir/unittests/Analysis/Presburger/SimplexTest.cpp
+++ b/mlir/unittests/Analysis/Presburger/SimplexTest.cpp
@@ -388,6 +388,7 @@ TEST(SimplexTest, appendVariable) {
 
   unsigned snapshot1 = simplex.getSnapshot();
   simplex.appendVariable();
+  simplex.appendVariable(0);
   EXPECT_EQ(simplex.getNumVariables(), 2u);
 
   int64_t yMin = 2, yMax = 5;