[llvm] [DominanceFrontier] make DominanceFrontierBase::find iterator deterministic (PR #69711)

[Wenju He via llvm-commits]

https://github.com/wenju-he created https://github.com/llvm/llvm-project/pull/69711

When we iterate over a basic block's dominance frontiers returned by
DominanceFrontierBase::find, the order of the dominance frontiers is
indeterministic. This results in indeterministic IR output in our
downstream use case that depends on the order.

>From 3bf2b65dd9ffc2e87b4527a72e82b3728c9be7e3 Mon Sep 17 00:00:00 2001
From: Wenju He <wenju.he at intel.com>
Date: Fri, 20 Oct 2023 19:09:52 +0800
Subject: [PATCH] [DominanceFrontier] make DominanceFrontierBase::find iterator
 deterministic

When we iterate over a basic block's dominance frontiers returned by
DominanceFrontierBase::find, the order of the dominance frontiers is
indeterministic. This results in indeterministic IR output in our
downstream use case that depends on the order.
---
 llvm/include/llvm/Analysis/DominanceFrontier.h     | 4 ++--
 llvm/include/llvm/Analysis/DominanceFrontierImpl.h | 6 +++---
 llvm/include/llvm/Analysis/RegionInfoImpl.h        | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/llvm/include/llvm/Analysis/DominanceFrontier.h b/llvm/include/llvm/Analysis/DominanceFrontier.h
index cef5e03b3b7a7c7..0f35b45cd2b2b04 100644
--- a/llvm/include/llvm/Analysis/DominanceFrontier.h
+++ b/llvm/include/llvm/Analysis/DominanceFrontier.h
@@ -18,13 +18,13 @@
 #define LLVM_ANALYSIS_DOMINANCEFRONTIER_H
 
 #include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/GenericDomTree.h"
 #include <cassert>
 #include <map>
-#include <set>
 #include <utility>
 
 namespace llvm {
@@ -39,7 +39,7 @@ class raw_ostream;
 template <class BlockT, bool IsPostDom>
 class DominanceFrontierBase {
 public:
-  using DomSetType = std::set<BlockT *>;                // Dom set for a bb
+  using DomSetType = SetVector<BlockT *>;               // Dom set for a bb
   using DomSetMapType = std::map<BlockT *, DomSetType>; // Dom set map
 
 protected:
diff --git a/llvm/include/llvm/Analysis/DominanceFrontierImpl.h b/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
index 3df51d9ad90815c..a9c415f47010943 100644
--- a/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
+++ b/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
@@ -49,7 +49,7 @@ template <class BlockT, bool IsPostDom>
 void DominanceFrontierBase<BlockT, IsPostDom>::removeBlock(BlockT *BB) {
   assert(find(BB) != end() && "Block is not in DominanceFrontier!");
   for (iterator I = begin(), E = end(); I != E; ++I)
-    I->second.erase(BB);
+    I->second.remove(BB);
   Frontiers.erase(BB);
 }
 
@@ -65,7 +65,7 @@ void DominanceFrontierBase<BlockT, IsPostDom>::removeFromFrontier(
     iterator I, BlockT *Node) {
   assert(I != end() && "BB is not in DominanceFrontier!");
   assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
-  I->second.erase(Node);
+  I->second.remove(Node);
 }
 
 template <class BlockT, bool IsPostDom>
@@ -133,7 +133,7 @@ void DominanceFrontierBase<BlockT, IsPostDom>::print(raw_ostream &OS) const {
       OS << " <<exit node>>";
     OS << " is:\t";
 
-    const std::set<BlockT *> &BBs = I->second;
+    const SetVector<BlockT *> &BBs = I->second;
 
     for (const BlockT *BB : BBs) {
       OS << ' ';
diff --git a/llvm/include/llvm/Analysis/RegionInfoImpl.h b/llvm/include/llvm/Analysis/RegionInfoImpl.h
index 2877a9f8f0e086a..ec79b35ae324a51 100644
--- a/llvm/include/llvm/Analysis/RegionInfoImpl.h
+++ b/llvm/include/llvm/Analysis/RegionInfoImpl.h
@@ -587,7 +587,7 @@ bool RegionInfoBase<Tr>::isRegion(BlockT *entry, BlockT *exit) const {
   for (BlockT *Succ : *entrySuccs) {
     if (Succ == exit || Succ == entry)
       continue;
-    if (exitSuccs->find(Succ) == exitSuccs->end())
+    if (!exitSuccs->contains(Succ))
       return false;
     if (!isCommonDomFrontier(Succ, entry, exit))
       return false;