From 08859be344670e39cdbbe539caa74272b0b4ad7f Mon Sep 17 00:00:00 2001
From: Hideto Ueno <uenoku.tokotoko@gmail.com>
Date: Wed, 15 Mar 2023 23:42:38 +0900
Subject: [PATCH] [ExtractInstances] Fix nondeterminism with MapVector. (#4749)
 (#4833)

This fixes nondeterminism caused by iteration over DenseMap. Instead use MapVector to guarantee determinism.
---
 lib/Dialect/FIRRTL/Transforms/ExtractInstances.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/Dialect/FIRRTL/Transforms/ExtractInstances.cpp b/lib/Dialect/FIRRTL/Transforms/ExtractInstances.cpp
index 31d88ea51363..e21241c73137 100644
--- a/lib/Dialect/FIRRTL/Transforms/ExtractInstances.cpp
+++ b/lib/Dialect/FIRRTL/Transforms/ExtractInstances.cpp
@@ -837,7 +837,7 @@ void ExtractInstancesPass::groupInstances() {
   // module. Note that we cannot group instances that landed in different parent
   // modules into the same submodule, so we use that parent module as a grouping
   // key.
-  SmallDenseMap<std::pair<Operation *, StringRef>, SmallVector<InstanceOp>>
+  llvm::MapVector<std::pair<Operation *, StringRef>, SmallVector<InstanceOp>>
       instsByWrapper;
   for (auto &[inst, info] : extractedInstances) {
     if (!info.wrapperModule.empty())