[Reg2Mem] add support for the new pass manager

This patch refactors the pass to accomodate the new pass manager
boilerplate.

Differential Revision: https://reviews.llvm.org/D91005

include/llvm/InitializePasses.h

@@ -365,7 +365,7 @@ void initializeReassociateLegacyPassPass(PassRegistry&);
 void initializeRedundantDbgInstEliminationPass(PassRegistry&);
 void initializeRegAllocFastPass(PassRegistry&);
 void initializeRegBankSelectPass(PassRegistry&);
-void initializeRegToMemPass(PassRegistry&);
+void initializeRegToMemLegacyPass(PassRegistry&);
 void initializeRegUsageInfoCollectorPass(PassRegistry&);
 void initializeRegUsageInfoPropagationPass(PassRegistry&);
 void initializeRegionInfoPassPass(PassRegistry&);

include/llvm/Transforms/Scalar/Reg2Mem.h

@@ -0,0 +1,27 @@
+//===- Reg2Mem.h - Convert registers to allocas -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the interface for the RegToMem Pass.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_REG2MEM_H
+#define LLVM_TRANSFORMS_SCALAR_REG2MEM_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class RegToMemPass : public PassInfoMixin<RegToMemPass> {
+public:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_SCALAR_REG2MEM_H

lib/Passes/PassBuilder.cpp

@@ -184,6 +184,7 @@
 #include "llvm/Transforms/Scalar/NewGVN.h"
 #include "llvm/Transforms/Scalar/PartiallyInlineLibCalls.h"
 #include "llvm/Transforms/Scalar/Reassociate.h"
+#include "llvm/Transforms/Scalar/Reg2Mem.h"
 #include "llvm/Transforms/Scalar/RewriteStatepointsForGC.h"
 #include "llvm/Transforms/Scalar/SCCP.h"
 #include "llvm/Transforms/Scalar/SROA.h"

lib/Passes/PassRegistry.def

@@ -282,6 +282,7 @@ FUNCTION_PASS("print-alias-sets", AliasSetsPrinterPass(dbgs()))
 FUNCTION_PASS("print-predicateinfo", PredicateInfoPrinterPass(dbgs()))
 FUNCTION_PASS("print-mustexecute", MustExecutePrinterPass(dbgs()))
 FUNCTION_PASS("reassociate", ReassociatePass())
+FUNCTION_PASS("reg2mem", RegToMemPass())
 FUNCTION_PASS("scalarizer", ScalarizerPass())
 FUNCTION_PASS("sccp", SCCPPass())
 FUNCTION_PASS("simplifycfg", SimplifyCFGPass())

lib/Transforms/Scalar/Reg2Mem.cpp

@@ -15,18 +15,23 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/Reg2Mem.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/LoopInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CFG.h"
+#include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <list>
 using namespace llvm;
@@ -36,43 +41,17 @@ using namespace llvm;
 STATISTIC(NumRegsDemoted, "Number of registers demoted");
 STATISTIC(NumPhisDemoted, "Number of phi-nodes demoted");
 
-namespace {
-  struct RegToMem : public FunctionPass {
-    static char ID; // Pass identification, replacement for typeid
-    RegToMem() : FunctionPass(ID) {
-      initializeRegToMemPass(*PassRegistry::getPassRegistry());
-    }
-
-    void getAnalysisUsage(AnalysisUsage &AU) const override {
-      AU.addRequiredID(BreakCriticalEdgesID);
-      AU.addPreservedID(BreakCriticalEdgesID);
-    }
-
-    bool valueEscapes(const Instruction &Inst) const {
-      const BasicBlock *BB = Inst.getParent();
-      for (const User *U : Inst.users()) {
-        const Instruction *UI = cast<Instruction>(U);
-        if (UI->getParent() != BB || isa<PHINode>(UI))
-          return true;
-      }
-      return false;
-    }
-
-    bool runOnFunction(Function &F) override;
-  };
+static bool valueEscapes(const Instruction &Inst) {
+  const BasicBlock *BB = Inst.getParent();
+  for (const User *U : Inst.users()) {
+    const Instruction *UI = cast<Instruction>(U);
+    if (UI->getParent() != BB || isa<PHINode>(UI))
+      return true;
+  }
+  return false;
 }
 
-char RegToMem::ID = 0;
-INITIALIZE_PASS_BEGIN(RegToMem, "reg2mem", "Demote all values to stack slots",
-                false, false)
-INITIALIZE_PASS_DEPENDENCY(BreakCriticalEdges)
-INITIALIZE_PASS_END(RegToMem, "reg2mem", "Demote all values to stack slots",
-                false, false)
-
-bool RegToMem::runOnFunction(Function &F) {
-  if (F.isDeclaration() || skipFunction(F))
-    return false;
-
+static bool runPass(Function &F) {
   // Insert all new allocas into entry block.
   BasicBlock *BBEntry = &F.getEntryBlock();
   assert(pred_empty(BBEntry) &&
@@ -115,9 +94,48 @@ bool RegToMem::runOnFunction(Function &F) {
   return true;
 }
 
+PreservedAnalyses RegToMemPass::run(Function &F, FunctionAnalysisManager &AM) {
+  auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
+  auto *LI = &AM.getResult<LoopAnalysis>(F);
+  unsigned N = SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions(DT, LI));
+  bool Changed = runPass(F);
+  if (N == 0 && !Changed)
+    return PreservedAnalyses::all();
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  PA.preserve<LoopAnalysis>();
+  return PA;
+}
+
+namespace {
+struct RegToMemLegacy : public FunctionPass {
+  static char ID; // Pass identification, replacement for typeid
+  RegToMemLegacy() : FunctionPass(ID) {
+    initializeRegToMemLegacyPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequiredID(BreakCriticalEdgesID);
+    AU.addPreservedID(BreakCriticalEdgesID);
+  }
+
+  bool runOnFunction(Function &F) override {
+    if (F.isDeclaration() || skipFunction(F))
+      return false;
+    return runPass(F);
+  }
+};
+} // namespace
+
+char RegToMemLegacy::ID = 0;
+INITIALIZE_PASS_BEGIN(RegToMemLegacy, "reg2mem",
+                      "Demote all values to stack slots", false, false)
+INITIALIZE_PASS_DEPENDENCY(BreakCriticalEdges)
+INITIALIZE_PASS_END(RegToMemLegacy, "reg2mem",
+                    "Demote all values to stack slots", false, false)
 
 // createDemoteRegisterToMemory - Provide an entry point to create this pass.
-char &llvm::DemoteRegisterToMemoryID = RegToMem::ID;
+char &llvm::DemoteRegisterToMemoryID = RegToMemLegacy::ID;
 FunctionPass *llvm::createDemoteRegisterToMemoryPass() {
-  return new RegToMem();
+  return new RegToMemLegacy();
 }

lib/Transforms/Scalar/Scalar.cpp

@@ -92,7 +92,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializePartiallyInlineLibCallsLegacyPassPass(Registry);
   initializeReassociateLegacyPassPass(Registry);
   initializeRedundantDbgInstEliminationPass(Registry);
-  initializeRegToMemPass(Registry);
+  initializeRegToMemLegacyPass(Registry);
   initializeRewriteStatepointsForGCLegacyPassPass(Registry);
   initializeSCCPLegacyPassPass(Registry);
   initializeSROALegacyPassPass(Registry);

test/Transforms/Reg2Mem/crash.ll

@@ -1,4 +1,5 @@
-; RUN: opt -reg2mem -disable-output -enable-new-pm=0 < %s
+; RUN: opt -passes=reg2mem -disable-output -enable-new-pm=1 < %s
+; RUN: opt -reg2mem -disable-output < %s
 ; PR14782
 
 declare void @f1()