[llvm] [NFC][LLVM] Namespace cleanup in LoopFuse (PR #163758)

[Rahul Joshi via llvm-commits]

https://github.com/jurahul updated https://github.com/llvm/llvm-project/pull/163758

>From 0f8e77bfc638b06fe7835440c40a417fd41f13d7 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Thu, 16 Oct 2025 05:16:49 -0700
Subject: [PATCH 1/2] [NFC][LLVM] Namespace cleanup in LoopFuse

Additionally, make the `Loop` argument to `printLoop` const.
---
 llvm/include/llvm/Analysis/LoopInfo.h   |  2 +-
 llvm/lib/Analysis/LoopInfo.cpp          |  4 ++--
 llvm/lib/Transforms/Scalar/LoopFuse.cpp | 32 +++++++++++++------------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/llvm/include/llvm/Analysis/LoopInfo.h b/llvm/include/llvm/Analysis/LoopInfo.h
index a7a6a2753709c..0ecb1141dc1be 100644
--- a/llvm/include/llvm/Analysis/LoopInfo.h
+++ b/llvm/include/llvm/Analysis/LoopInfo.h
@@ -617,7 +617,7 @@ class LLVM_ABI LoopInfoWrapperPass : public FunctionPass {
 };
 
 /// Function to print a loop's contents as LLVM's text IR assembly.
-LLVM_ABI void printLoop(Loop &L, raw_ostream &OS,
+LLVM_ABI void printLoop(const Loop &L, raw_ostream &OS,
                         const std::string &Banner = "");
 
 /// Find and return the loop attribute node for the attribute @p Name in
diff --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index a8c3173bb1794..d84721b7f8f4b 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -986,8 +986,8 @@ PreservedAnalyses LoopPrinterPass::run(Function &F,
   return PreservedAnalyses::all();
 }
 
-void llvm::printLoop(Loop &L, raw_ostream &OS, const std::string &Banner) {
-
+void llvm::printLoop(const Loop &L, raw_ostream &OS,
+                     const std::string &Banner) {
   if (forcePrintModuleIR()) {
     // handling -print-module-scope
     OS << Banner << " (loop: ";
diff --git a/llvm/lib/Transforms/Scalar/LoopFuse.cpp b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
index 2073303237f69..90b8ec83b2648 100644
--- a/llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -368,7 +368,7 @@ struct FusionCandidate {
     Valid = false;
   }
 
-  bool reportInvalidCandidate(llvm::Statistic &Stat) const {
+  bool reportInvalidCandidate(Statistic &Stat) const {
     using namespace ore;
     assert(L && Preheader && "Fusion candidate not initialized properly!");
 #if LLVM_ENABLE_STATS
@@ -445,9 +445,19 @@ struct FusionCandidateCompare {
         "No dominance relationship between these fusion candidates!");
   }
 };
+} // namespace
 
 using LoopVector = SmallVector<Loop *, 4>;
 
+#ifndef NDEBUG
+static void printLoopVector(const LoopVector &LV) {
+  dbgs() << "****************************\n";
+  for (const Loop *L : LV)
+    printLoop(*L, dbgs());
+  dbgs() << "****************************\n";
+}
+#endif
+
 // Set of Control Flow Equivalent (CFE) Fusion Candidates, sorted in dominance
 // order. Thus, if FC0 comes *before* FC1 in a FusionCandidateSet, then FC0
 // dominates FC1 and FC1 post-dominates FC0.
@@ -462,8 +472,7 @@ using FusionCandidateSet = std::set<FusionCandidate, FusionCandidateCompare>;
 using FusionCandidateCollection = SmallVector<FusionCandidateSet, 4>;
 
 #if !defined(NDEBUG)
-static llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
-                                     const FusionCandidate &FC) {
+static raw_ostream &operator<<(raw_ostream &OS, const FusionCandidate &FC) {
   if (FC.isValid())
     OS << FC.Preheader->getName();
   else
@@ -472,8 +481,8 @@ static llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
   return OS;
 }
 
-static llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
-                                     const FusionCandidateSet &CandSet) {
+static raw_ostream &operator<<(raw_ostream &OS,
+                               const FusionCandidateSet &CandSet) {
   for (const FusionCandidate &FC : CandSet)
     OS << FC << '\n';
 
@@ -491,6 +500,8 @@ printFusionCandidates(const FusionCandidateCollection &FusionCandidates) {
 }
 #endif
 
+namespace {
+
 /// Collect all loops in function at the same nest level, starting at the
 /// outermost level.
 ///
@@ -550,15 +561,6 @@ struct LoopDepthTree {
   LoopsOnLevelTy LoopsOnLevel;
 };
 
-#ifndef NDEBUG
-static void printLoopVector(const LoopVector &LV) {
-  dbgs() << "****************************\n";
-  for (auto *L : LV)
-    printLoop(*L, dbgs());
-  dbgs() << "****************************\n";
-}
-#endif
-
 struct LoopFuser {
 private:
   // Sets of control flow equivalent fusion candidates for a given nest level.
@@ -1850,7 +1852,7 @@ struct LoopFuser {
   ///       <Cand1 Preheader> and <Cand2 Preheader>: <Stat Description>
   template <typename RemarkKind>
   void reportLoopFusion(const FusionCandidate &FC0, const FusionCandidate &FC1,
-                        llvm::Statistic &Stat) {
+                        Statistic &Stat) {
     assert(FC0.Preheader && FC1.Preheader &&
            "Expecting valid fusion candidates");
     using namespace ore;

>From efa0cfff4a51d0c6c5e78b503d618c4e4c096de2 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Thu, 16 Oct 2025 09:43:52 -0700
Subject: [PATCH 2/2] Review feedback

---
 llvm/lib/Transforms/Scalar/LoopFuse.cpp | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/LoopFuse.cpp b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
index 90b8ec83b2648..19eccb9e17020 100644
--- a/llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -449,15 +449,6 @@ struct FusionCandidateCompare {
 
 using LoopVector = SmallVector<Loop *, 4>;
 
-#ifndef NDEBUG
-static void printLoopVector(const LoopVector &LV) {
-  dbgs() << "****************************\n";
-  for (const Loop *L : LV)
-    printLoop(*L, dbgs());
-  dbgs() << "****************************\n";
-}
-#endif
-
 // Set of Control Flow Equivalent (CFE) Fusion Candidates, sorted in dominance
 // order. Thus, if FC0 comes *before* FC1 in a FusionCandidateSet, then FC0
 // dominates FC1 and FC1 post-dominates FC0.
@@ -471,7 +462,14 @@ static void printLoopVector(const LoopVector &LV) {
 using FusionCandidateSet = std::set<FusionCandidate, FusionCandidateCompare>;
 using FusionCandidateCollection = SmallVector<FusionCandidateSet, 4>;
 
-#if !defined(NDEBUG)
+#ifndef NDEBUG
+static void printLoopVector(const LoopVector &LV) {
+  dbgs() << "****************************\n";
+  for (const Loop *L : LV)
+    printLoop(*L, dbgs());
+  dbgs() << "****************************\n";
+}
+
 static raw_ostream &operator<<(raw_ostream &OS, const FusionCandidate &FC) {
   if (FC.isValid())
     OS << FC.Preheader->getName();
@@ -498,7 +496,7 @@ printFusionCandidates(const FusionCandidateCollection &FusionCandidates) {
     dbgs() << "****************************\n";
   }
 }
-#endif
+#endif // NDEBUG
 
 namespace {