[CodeGen][NPM] Port UnreachableMachineBlockElim to NPM (#136127)

diff --git a/llvm/include/llvm/CodeGen/UnreachableBlockElim.h b/llvm/include/llvm/CodeGen/UnreachableBlockElim.h
index 7dbae77..3c2b701 100644
--- a/llvm/include/llvm/CodeGen/UnreachableBlockElim.h
+++ b/llvm/include/llvm/CodeGen/UnreachableBlockElim.h

@@ -22,6 +22,7 @@
 #ifndef LLVM_CODEGEN_UNREACHABLEBLOCKELIM_H
 #define LLVM_CODEGEN_UNREACHABLEBLOCKELIM_H
 
+#include "llvm/CodeGen/MachinePassManager.h"
 #include "llvm/IR/PassManager.h"
 
 namespace llvm {
@@ -31,6 +32,13 @@
 public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
+
+class UnreachableMachineBlockElimPass
+    : public PassInfoMixin<UnreachableMachineBlockElimPass> {
+public:
+  PreservedAnalyses run(MachineFunction &F, MachineFunctionAnalysisManager &AM);
+};
+
 } // end namespace llvm
 
 #endif // LLVM_CODEGEN_UNREACHABLEBLOCKELIM_H

diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 9fd8f82..9bef8e4 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h

@@ -315,7 +315,7 @@
 void initializeUnifyLoopExitsLegacyPassPass(PassRegistry &);
 void initializeUnpackMachineBundlesPass(PassRegistry &);
 void initializeUnreachableBlockElimLegacyPassPass(PassRegistry &);
-void initializeUnreachableMachineBlockElimPass(PassRegistry &);
+void initializeUnreachableMachineBlockElimLegacyPass(PassRegistry &);
 void initializeVerifierLegacyPassPass(PassRegistry &);
 void initializeVirtRegMapWrapperLegacyPass(PassRegistry &);
 void initializeVirtRegRewriterPass(PassRegistry &);

diff --git a/llvm/include/llvm/Passes/CodeGenPassBuilder.h b/llvm/include/llvm/Passes/CodeGenPassBuilder.h
index d092049..61e377d 100644
--- a/llvm/include/llvm/Passes/CodeGenPassBuilder.h
+++ b/llvm/include/llvm/Passes/CodeGenPassBuilder.h

@@ -47,6 +47,7 @@
 #include "llvm/CodeGen/JMCInstrumenter.h"
 #include "llvm/CodeGen/LiveDebugValuesPass.h"
 #include "llvm/CodeGen/LiveIntervals.h"
+#include "llvm/CodeGen/LiveVariables.h"
 #include "llvm/CodeGen/LocalStackSlotAllocation.h"
 #include "llvm/CodeGen/LowerEmuTLS.h"
 #include "llvm/CodeGen/MIRPrinter.h"
@@ -1172,7 +1173,21 @@
 
   addPass(ProcessImplicitDefsPass());
 
+  // LiveVariables currently requires pure SSA form.
+  //
+  // FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
+  // LiveVariables can be removed completely, and LiveIntervals can be directly
+  // computed. (We still either need to regenerate kill flags after regalloc, or
+  // preferably fix the scavenger to not depend on them).
+  // FIXME: UnreachableMachineBlockElim is a dependant pass of LiveVariables.
+  // When LiveVariables is removed this has to be removed/moved either.
+  // Explicit addition of UnreachableMachineBlockElim allows stopping before or
+  // after it with -stop-before/-stop-after.
+  addPass(UnreachableMachineBlockElimPass());
+  addPass(RequireAnalysisPass<LiveVariablesAnalysis, MachineFunction>());
+
   // Edge splitting is smarter with machine loop info.
+  addPass(RequireAnalysisPass<MachineLoopAnalysis, MachineFunction>());
   addPass(PHIEliminationPass());
 
   // Eventually, we want to run LiveIntervals before PHI elimination.

diff --git a/llvm/include/llvm/Passes/MachinePassRegistry.def b/llvm/include/llvm/Passes/MachinePassRegistry.def
index fff5083..8c22a28 100644
--- a/llvm/include/llvm/Passes/MachinePassRegistry.def
+++ b/llvm/include/llvm/Passes/MachinePassRegistry.def

@@ -194,6 +194,8 @@
 MACHINE_FUNCTION_PASS("tailduplication", TailDuplicatePass())
 MACHINE_FUNCTION_PASS("trigger-verifier-error", TriggerVerifierErrorPass())
 MACHINE_FUNCTION_PASS("two-address-instruction", TwoAddressInstructionPass())
+MACHINE_FUNCTION_PASS("unreachable-mbb-elimination", 
+                      UnreachableMachineBlockElimPass())
 MACHINE_FUNCTION_PASS("verify", MachineVerifierPass())
 MACHINE_FUNCTION_PASS("verify<machine-trace-metrics>", MachineTraceMetricsVerifierPass())
 MACHINE_FUNCTION_PASS("xray-instrumentation", XRayInstrumentationPass())

diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index 2b0e938..a34adcf 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp

@@ -140,7 +140,7 @@
   initializeTypePromotionLegacyPass(Registry);
   initializeUnpackMachineBundlesPass(Registry);
   initializeUnreachableBlockElimLegacyPassPass(Registry);
-  initializeUnreachableMachineBlockElimPass(Registry);
+  initializeUnreachableMachineBlockElimLegacyPass(Registry);
   initializeVirtRegMapWrapperLegacyPass(Registry);
   initializeVirtRegRewriterPass(Registry);
   initializeWasmEHPreparePass(Registry);

diff --git a/llvm/lib/CodeGen/LiveVariables.cpp b/llvm/lib/CodeGen/LiveVariables.cpp
index ab95200..f8e058383 100644
--- a/llvm/lib/CodeGen/LiveVariables.cpp
+++ b/llvm/lib/CodeGen/LiveVariables.cpp

@@ -61,7 +61,7 @@
 char &llvm::LiveVariablesID = LiveVariablesWrapperPass::ID;
 INITIALIZE_PASS_BEGIN(LiveVariablesWrapperPass, "livevars",
                       "Live Variable Analysis", false, false)
-INITIALIZE_PASS_DEPENDENCY(UnreachableMachineBlockElim)
+INITIALIZE_PASS_DEPENDENCY(UnreachableMachineBlockElimLegacy)
 INITIALIZE_PASS_END(LiveVariablesWrapperPass, "livevars",
                     "Live Variable Analysis", false, false)
 

diff --git a/llvm/lib/CodeGen/UnreachableBlockElim.cpp b/llvm/lib/CodeGen/UnreachableBlockElim.cpp
index aa4ccec..f9f7b47 100644
--- a/llvm/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/llvm/lib/CodeGen/UnreachableBlockElim.cpp

@@ -72,32 +72,58 @@
 }
 
 namespace {
-  class UnreachableMachineBlockElim : public MachineFunctionPass {
-    bool runOnMachineFunction(MachineFunction &F) override;
-    void getAnalysisUsage(AnalysisUsage &AU) const override;
+class UnreachableMachineBlockElim {
+  MachineDominatorTree *MDT;
+  MachineLoopInfo *MLI;
 
-  public:
-    static char ID; // Pass identification, replacement for typeid
-    UnreachableMachineBlockElim() : MachineFunctionPass(ID) {}
-  };
-}
-char UnreachableMachineBlockElim::ID = 0;
+public:
+  UnreachableMachineBlockElim(MachineDominatorTree *MDT, MachineLoopInfo *MLI)
+      : MDT(MDT), MLI(MLI) {}
+  bool run(MachineFunction &MF);
+};
 
-INITIALIZE_PASS(UnreachableMachineBlockElim, "unreachable-mbb-elimination",
-  "Remove unreachable machine basic blocks", false, false)
+class UnreachableMachineBlockElimLegacy : public MachineFunctionPass {
+  bool runOnMachineFunction(MachineFunction &F) override;
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
 
-char &llvm::UnreachableMachineBlockElimID = UnreachableMachineBlockElim::ID;
+public:
+  static char ID; // Pass identification, replacement for typeid
+  UnreachableMachineBlockElimLegacy() : MachineFunctionPass(ID) {}
+};
+} // namespace
 
-void UnreachableMachineBlockElim::getAnalysisUsage(AnalysisUsage &AU) const {
+char UnreachableMachineBlockElimLegacy::ID = 0;
+
+INITIALIZE_PASS(UnreachableMachineBlockElimLegacy,
+                "unreachable-mbb-elimination",
+                "Remove unreachable machine basic blocks", false, false)
+
+char &llvm::UnreachableMachineBlockElimID =
+    UnreachableMachineBlockElimLegacy::ID;
+
+void UnreachableMachineBlockElimLegacy::getAnalysisUsage(
+    AnalysisUsage &AU) const {
   AU.addPreserved<MachineLoopInfoWrapperPass>();
   AU.addPreserved<MachineDominatorTreeWrapperPass>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
-bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
-  df_iterator_default_set<MachineBasicBlock*> Reachable;
-  bool ModifiedPHI = false;
+PreservedAnalyses
+UnreachableMachineBlockElimPass::run(MachineFunction &MF,
+                                     MachineFunctionAnalysisManager &AM) {
+  auto *MDT = AM.getCachedResult<MachineDominatorTreeAnalysis>(MF);
+  auto *MLI = AM.getCachedResult<MachineLoopAnalysis>(MF);
 
+  if (!UnreachableMachineBlockElim(MDT, MLI).run(MF))
+    return PreservedAnalyses::all();
+
+  return getMachineFunctionPassPreservedAnalyses()
+      .preserve<MachineLoopAnalysis>()
+      .preserve<MachineDominatorTreeAnalysis>();
+}
+
+bool UnreachableMachineBlockElimLegacy::runOnMachineFunction(
+    MachineFunction &MF) {
   MachineDominatorTreeWrapperPass *MDTWrapper =
       getAnalysisIfAvailable<MachineDominatorTreeWrapperPass>();
   MachineDominatorTree *MDT = MDTWrapper ? &MDTWrapper->getDomTree() : nullptr;
@@ -105,6 +131,13 @@
       getAnalysisIfAvailable<MachineLoopInfoWrapperPass>();
   MachineLoopInfo *MLI = MLIWrapper ? &MLIWrapper->getLI() : nullptr;
 
+  return UnreachableMachineBlockElim(MDT, MLI).run(MF);
+}
+
+bool UnreachableMachineBlockElim::run(MachineFunction &F) {
+  df_iterator_default_set<MachineBasicBlock *> Reachable;
+  bool ModifiedPHI = false;
+
   // Mark all reachable blocks.
   for (MachineBasicBlock *BB : depth_first_ext(&F, Reachable))
     (void)BB/* Mark all reachable blocks */;

diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index a5c624b..e7057d9 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp

@@ -167,6 +167,7 @@
 #include "llvm/CodeGen/TargetPassConfig.h"
 #include "llvm/CodeGen/TwoAddressInstructionPass.h"
 #include "llvm/CodeGen/TypePromotion.h"
+#include "llvm/CodeGen/UnreachableBlockElim.h"
 #include "llvm/CodeGen/VirtRegMap.h"
 #include "llvm/CodeGen/WasmEHPrepare.h"
 #include "llvm/CodeGen/WinEHPrepare.h"

diff --git a/llvm/test/CodeGen/Hexagon/unreachable-mbb-phi-subreg.mir b/llvm/test/CodeGen/Hexagon/unreachable-mbb-phi-subreg.mir
index 79f9d5d..697c423 100644
--- a/llvm/test/CodeGen/Hexagon/unreachable-mbb-phi-subreg.mir
+++ b/llvm/test/CodeGen/Hexagon/unreachable-mbb-phi-subreg.mir

@@ -1,4 +1,5 @@
 # RUN: llc -mtriple=hexagon -run-pass unreachable-mbb-elimination %s -o - | FileCheck %s
+# RUN: llc -mtriple=hexagon -passes unreachable-mbb-elimination %s -o - | FileCheck %s
 
 ---
 name: fred

diff --git a/llvm/test/DebugInfo/MIR/X86/unreachable-block-call-site.mir b/llvm/test/DebugInfo/MIR/X86/unreachable-block-call-site.mir
index e77192d..feb5f12 100644
--- a/llvm/test/DebugInfo/MIR/X86/unreachable-block-call-site.mir
+++ b/llvm/test/DebugInfo/MIR/X86/unreachable-block-call-site.mir

@@ -1,4 +1,5 @@
 # RUN: llc -emit-call-site-info -mtriple=x86_64-pc-linux -run-pass=unreachable-mbb-elimination -o - %s | FileCheck %s
+# RUN: llc -emit-call-site-info -mtriple=x86_64-pc-linux -passes=unreachable-mbb-elimination -o - %s | FileCheck %s
 
 # Verify that the call site information for the call residing in the eliminated
 # block is removed. This test case would previously trigger an assertion when