[llvm] [NewPM] Remove UnifyFunctionExitNodesLegacyPass (PR #72816)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/72816

UnifyFunctionExitNodesLegacyPass isn't used anywhere in upstream and thus isn't tested at all. For these reasons, remove it.

>From b035028cbf0311117ed59c75eb2d00b59af172d5 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Sun, 19 Nov 2023 16:41:58 -0800
Subject: [PATCH] [NewPM] Remove UnifyFunctionExitNodesLegacyPass

UnifyFunctionExitNodesLegacyPass isn't used anywhere in upstream and
thus isn't tested at all. For these reasons, remove it.
---
 llvm/include/llvm/InitializePasses.h          |  1 -
 llvm/include/llvm/LinkAllPasses.h             |  2 --
 .../Transforms/Utils/UnifyFunctionExitNodes.h | 13 --------
 .../Utils/UnifyFunctionExitNodes.cpp          | 32 -------------------
 llvm/lib/Transforms/Utils/Utils.cpp           |  1 -
 5 files changed, 49 deletions(-)

diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index da38a38b87ebc4d..8e5332a228a71ba 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -327,7 +327,6 @@ void initializeTwoAddressInstructionPassPass(PassRegistry&);
 void initializeTypeBasedAAWrapperPassPass(PassRegistry&);
 void initializeTypePromotionLegacyPass(PassRegistry&);
 void initializeUniformityInfoWrapperPassPass(PassRegistry &);
-void initializeUnifyFunctionExitNodesLegacyPassPass(PassRegistry &);
 void initializeUnifyLoopExitsLegacyPassPass(PassRegistry &);
 void initializeUnpackMachineBundlesPass(PassRegistry&);
 void initializeUnreachableBlockElimLegacyPassPass(PassRegistry&);
diff --git a/llvm/include/llvm/LinkAllPasses.h b/llvm/include/llvm/LinkAllPasses.h
index 3fc90e85c3533e2..9761264b0b761f5 100644
--- a/llvm/include/llvm/LinkAllPasses.h
+++ b/llvm/include/llvm/LinkAllPasses.h
@@ -44,7 +44,6 @@
 #include "llvm/Transforms/Scalar/Scalarizer.h"
 #include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/SymbolRewriter.h"
-#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
 #include "llvm/Transforms/Vectorize/LoadStoreVectorizer.h"
 #include <cstdlib>
 
@@ -121,7 +120,6 @@ namespace {
       (void) llvm::createSingleLoopExtractorPass();
       (void) llvm::createTailCallEliminationPass();
       (void)llvm::createTLSVariableHoistPass();
-      (void) llvm::createUnifyFunctionExitNodesPass();
       (void) llvm::createInstCountPass();
       (void) llvm::createConstantHoistingPass();
       (void) llvm::createCodeGenPreparePass();
diff --git a/llvm/include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h b/llvm/include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h
index 461669d6a217876..296d3b755e2c85e 100644
--- a/llvm/include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h
+++ b/llvm/include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h
@@ -19,19 +19,6 @@
 
 namespace llvm {
 
-class UnifyFunctionExitNodesLegacyPass : public FunctionPass {
-public:
-  static char ID; // Pass identification, replacement for typeid
-  UnifyFunctionExitNodesLegacyPass();
-
-  // We can preserve non-critical-edgeness when we unify function exit nodes
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-  bool runOnFunction(Function &F) override;
-};
-
-Pass *createUnifyFunctionExitNodesPass();
-
 class UnifyFunctionExitNodesPass
     : public PassInfoMixin<UnifyFunctionExitNodesPass> {
 public:
diff --git a/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index e5adbe5133cf457..d5468909dd4ea75 100644
--- a/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
+++ b/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -16,31 +16,9 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Type.h"
-#include "llvm/InitializePasses.h"
 #include "llvm/Transforms/Utils.h"
 using namespace llvm;
 
-char UnifyFunctionExitNodesLegacyPass::ID = 0;
-
-UnifyFunctionExitNodesLegacyPass::UnifyFunctionExitNodesLegacyPass()
-    : FunctionPass(ID) {
-  initializeUnifyFunctionExitNodesLegacyPassPass(
-      *PassRegistry::getPassRegistry());
-}
-
-INITIALIZE_PASS(UnifyFunctionExitNodesLegacyPass, "mergereturn",
-                "Unify function exit nodes", false, false)
-
-Pass *llvm::createUnifyFunctionExitNodesPass() {
-  return new UnifyFunctionExitNodesLegacyPass();
-}
-
-void UnifyFunctionExitNodesLegacyPass::getAnalysisUsage(
-    AnalysisUsage &AU) const {
-  // We preserve the non-critical-edgeness property
-  AU.addPreservedID(BreakCriticalEdgesID);
-}
-
 namespace {
 
 bool unifyUnreachableBlocks(Function &F) {
@@ -108,16 +86,6 @@ bool unifyReturnBlocks(Function &F) {
 }
 } // namespace
 
-// Unify all exit nodes of the CFG by creating a new BasicBlock, and converting
-// all returns to unconditional branches to this new basic block. Also, unify
-// all unreachable blocks.
-bool UnifyFunctionExitNodesLegacyPass::runOnFunction(Function &F) {
-  bool Changed = false;
-  Changed |= unifyUnreachableBlocks(F);
-  Changed |= unifyReturnBlocks(F);
-  return Changed;
-}
-
 PreservedAnalyses UnifyFunctionExitNodesPass::run(Function &F,
                                                   FunctionAnalysisManager &AM) {
   bool Changed = false;
diff --git a/llvm/lib/Transforms/Utils/Utils.cpp b/llvm/lib/Transforms/Utils/Utils.cpp
index 91c743f17764123..f096c1ec7540c39 100644
--- a/llvm/lib/Transforms/Utils/Utils.cpp
+++ b/llvm/lib/Transforms/Utils/Utils.cpp
@@ -30,7 +30,6 @@ void llvm::initializeTransformUtils(PassRegistry &Registry) {
   initializeLowerInvokeLegacyPassPass(Registry);
   initializeLowerSwitchLegacyPassPass(Registry);
   initializePromoteLegacyPassPass(Registry);
-  initializeUnifyFunctionExitNodesLegacyPassPass(Registry);
   initializeStripGCRelocatesLegacyPass(Registry);
   initializePredicateInfoPrinterLegacyPassPass(Registry);
   initializeFixIrreduciblePass(Registry);