4 files changed, 41 insertions, 25 deletions
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index bea1bbe0dac..b277c0bb609 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -81,7 +81,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeTargetPassConfigPass(Registry);
   initializeTwoAddressInstructionPassPass(Registry);
   initializeUnpackMachineBundlesPass(Registry);
-  initializeUnreachableBlockElimPass(Registry);
+  initializeUnreachableBlockElimLegacyPassPass(Registry);
   initializeUnreachableMachineBlockElimPass(Registry);
   initializeVirtRegMapPass(Registry);
   initializeVirtRegRewriterPass(Registry);
diff --git a/llvm/lib/CodeGen/UnreachableBlockElim.cpp b/llvm/lib/CodeGen/UnreachableBlockElim.cpp
index 39aa1e4919a..501e01c45a8 100644
--- a/llvm/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/llvm/lib/CodeGen/UnreachableBlockElim.cpp
@@ -20,7 +20,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/UnreachableBlockElim.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/CodeGen/MachineDominators.h"
@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Dominators.h"
@@ -38,29 +39,7 @@
 #include "llvm/Target/TargetInstrInfo.h"
 using namespace llvm;
 
-namespace {
-  class UnreachableBlockElim : public FunctionPass {
-    bool runOnFunction(Function &F) override;
-  public:
-    static char ID; // Pass identification, replacement for typeid
-    UnreachableBlockElim() : FunctionPass(ID) {
-      initializeUnreachableBlockElimPass(*PassRegistry::getPassRegistry());
-    }
-
-    void getAnalysisUsage(AnalysisUsage &AU) const override {
-      AU.addPreserved<DominatorTreeWrapperPass>();
-    }
-  };
-}
-char UnreachableBlockElim::ID = 0;
-INITIALIZE_PASS(UnreachableBlockElim, "unreachableblockelim",
-                "Remove unreachable blocks from the CFG", false, false)
-
-FunctionPass *llvm::createUnreachableBlockEliminationPass() {
-  return new UnreachableBlockElim();
-}
-
-bool UnreachableBlockElim::runOnFunction(Function &F) {
+static bool eliminateUnreachableBlock(Function &F) {
   SmallPtrSet<BasicBlock*, 8> Reachable;
 
   // Mark all reachable blocks.
@@ -91,6 +70,41 @@ bool UnreachableBlockElim::runOnFunction(Function &F) {
   return !DeadBlocks.empty();
 }
 
+namespace {
+class UnreachableBlockElimLegacyPass : public FunctionPass {
+  bool runOnFunction(Function &F) override {
+    return eliminateUnreachableBlock(F);
+  }
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+  UnreachableBlockElimLegacyPass() : FunctionPass(ID) {
+    initializeUnreachableBlockElimLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addPreserved<DominatorTreeWrapperPass>();
+  }
+};
+}
+char UnreachableBlockElimLegacyPass::ID = 0;
+INITIALIZE_PASS(UnreachableBlockElimLegacyPass, "unreachableblockelim",
+                "Remove unreachable blocks from the CFG", false, false)
+
+FunctionPass *llvm::createUnreachableBlockEliminationPass() {
+  return new UnreachableBlockElimLegacyPass();
+}
+
+PreservedAnalyses UnreachableBlockElimPass::run(Function &F,
+                                                FunctionAnalysisManager &AM) {
+  bool Changed = eliminateUnreachableBlock(F);
+  if (!Changed)
+    return PreservedAnalyses::all();
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  return PA;
+}
 
 namespace {
   class UnreachableMachineBlockElim : public MachineFunctionPass {
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index bed602325e9..d7b8eca407d 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
 #include "llvm/CodeGen/PreISelIntrinsicLowering.h"
+#include "llvm/CodeGen/UnreachableBlockElim.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/PassManager.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index 3bc73771f89..037f24f8305 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -165,6 +165,7 @@ FUNCTION_PASS("sink", SinkingPass())
 FUNCTION_PASS("slp-vectorizer", SLPVectorizerPass())
 FUNCTION_PASS("sroa", SROA())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
+FUNCTION_PASS("unreachableblockelim", UnreachableBlockElimPass())
 FUNCTION_PASS("verify", VerifierPass())
 FUNCTION_PASS("verify<domtree>", DominatorTreeVerifierPass())
 FUNCTION_PASS("verify<memoryssa>", MemorySSAVerifierPass())