[llvm] [NewPM] Remove LoopSimplifyCFGLegacyPass (PR #72930)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/72930

This pass isn't used anywhere in upstream and thus has no test coverage. For these reasons, remove it.

>From 080107b7a38650b54a52b0ae9f3b4a98bc1f6fdd Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Mon, 20 Nov 2023 16:50:39 -0800
Subject: [PATCH] [NewPM] Remove LoopSimplifyCFGLegacyPass

This pass isn't used anywhere in upstream and thus has no test coverage.
For these reasons, remove it.
---
 llvm/include/llvm/InitializePasses.h          |  1 -
 llvm/include/llvm/LinkAllPasses.h             |  1 -
 llvm/include/llvm/Transforms/Scalar.h         |  7 ---
 .../lib/Transforms/Scalar/LoopSimplifyCFG.cpp | 51 -------------------
 llvm/lib/Transforms/Scalar/Scalar.cpp         |  1 -
 5 files changed, 61 deletions(-)

diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 2305db4f775d49c..b3da080dba5a76a 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -177,7 +177,6 @@ void initializeLoopInfoWrapperPassPass(PassRegistry&);
 void initializeLoopPassPass(PassRegistry&);
 void initializeLoopPredicationLegacyPassPass(PassRegistry&);
 void initializeLoopRotateLegacyPassPass(PassRegistry&);
-void initializeLoopSimplifyCFGLegacyPassPass(PassRegistry&);
 void initializeLoopSimplifyPass(PassRegistry&);
 void initializeLoopStrengthReducePass(PassRegistry&);
 void initializeLoopUnrollPass(PassRegistry&);
diff --git a/llvm/include/llvm/LinkAllPasses.h b/llvm/include/llvm/LinkAllPasses.h
index 0d15481034151df..51cd21f73cd8c3a 100644
--- a/llvm/include/llvm/LinkAllPasses.h
+++ b/llvm/include/llvm/LinkAllPasses.h
@@ -90,7 +90,6 @@ namespace {
       (void) llvm::createLoopExtractorPass();
       (void) llvm::createLoopPredicationPass();
       (void) llvm::createLoopSimplifyPass();
-      (void) llvm::createLoopSimplifyCFGPass();
       (void) llvm::createLoopStrengthReducePass();
       (void) llvm::createLoopUnrollPass();
       (void) llvm::createLoopRotatePass();
diff --git a/llvm/include/llvm/Transforms/Scalar.h b/llvm/include/llvm/Transforms/Scalar.h
index 111e5446603d26b..bff533b09ff28ba 100644
--- a/llvm/include/llvm/Transforms/Scalar.h
+++ b/llvm/include/llvm/Transforms/Scalar.h
@@ -237,13 +237,6 @@ FunctionPass *createNaryReassociatePass();
 //
 FunctionPass *createLoopDataPrefetchPass();
 
-//===----------------------------------------------------------------------===//
-//
-// LoopSimplifyCFG - This pass performs basic CFG simplification on loops,
-// primarily to help other loop passes.
-//
-Pass *createLoopSimplifyCFGPass();
-
 //===----------------------------------------------------------------------===//
 //
 // This pass does instruction simplification on each
diff --git a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index 8d59fdff9236f84..028a487ecdbc283 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -20,13 +20,11 @@
 #include "llvm/Analysis/DomTreeUpdater.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopIterator.h"
-#include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/MemorySSA.h"
 #include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRBuilder.h"
-#include "llvm/InitializePasses.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
@@ -734,52 +732,3 @@ PreservedAnalyses LoopSimplifyCFGPass::run(Loop &L, LoopAnalysisManager &AM,
     PA.preserve<MemorySSAAnalysis>();
   return PA;
 }
-
-namespace {
-class LoopSimplifyCFGLegacyPass : public LoopPass {
-public:
-  static char ID; // Pass ID, replacement for typeid
-  LoopSimplifyCFGLegacyPass() : LoopPass(ID) {
-    initializeLoopSimplifyCFGLegacyPassPass(*PassRegistry::getPassRegistry());
-  }
-
-  bool runOnLoop(Loop *L, LPPassManager &LPM) override {
-    if (skipLoop(L))
-      return false;
-
-    DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-    LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
-    ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
-    auto *MSSAA = getAnalysisIfAvailable<MemorySSAWrapperPass>();
-    std::optional<MemorySSAUpdater> MSSAU;
-    if (MSSAA)
-      MSSAU = MemorySSAUpdater(&MSSAA->getMSSA());
-    if (MSSAA && VerifyMemorySSA)
-      MSSAU->getMemorySSA()->verifyMemorySSA();
-    bool DeleteCurrentLoop = false;
-    bool Changed = simplifyLoopCFG(*L, DT, LI, SE, MSSAU ? &*MSSAU : nullptr,
-                                   DeleteCurrentLoop);
-    if (DeleteCurrentLoop)
-      LPM.markLoopAsDeleted(*L);
-    return Changed;
-  }
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.addPreserved<MemorySSAWrapperPass>();
-    AU.addPreserved<DependenceAnalysisWrapperPass>();
-    getLoopAnalysisUsage(AU);
-  }
-};
-} // end namespace
-
-char LoopSimplifyCFGLegacyPass::ID = 0;
-INITIALIZE_PASS_BEGIN(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
-                      "Simplify loop CFG", false, false)
-INITIALIZE_PASS_DEPENDENCY(LoopPass)
-INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
-INITIALIZE_PASS_END(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
-                    "Simplify loop CFG", false, false)
-
-Pass *llvm::createLoopSimplifyCFGPass() {
-  return new LoopSimplifyCFGLegacyPass();
-}
diff --git a/llvm/lib/Transforms/Scalar/Scalar.cpp b/llvm/lib/Transforms/Scalar/Scalar.cpp
index 80db06b03a901b3..bc69fc0483e09a5 100644
--- a/llvm/lib/Transforms/Scalar/Scalar.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalar.cpp
@@ -55,5 +55,4 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeSpeculativeExecutionLegacyPassPass(Registry);
   initializeStraightLineStrengthReduceLegacyPassPass(Registry);
   initializePlaceBackedgeSafepointsLegacyPassPass(Registry);
-  initializeLoopSimplifyCFGLegacyPassPass(Registry);
 }