[Reg2Mem] add support for the new pass manager

[tammela]

Summary

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

[dmgreen]

Nice. Looks very sensible. I've added some folks who may know more.

llvm/include/llvm/Transforms/Scalar/Reg2Mem.h

2

Can you line this up a little.

llvm/test/Transforms/Reg2Mem/crash.ll

1

Can you add an explicit new pass manager run line

[tammela]

Add test case, fix line column

[aeubanks]

2 nits, otherwise lgtm

llvm/include/llvm/Transforms/Scalar/Reg2Mem.h

23

delete?

llvm/test/Transforms/Reg2Mem/crash.ll

1–2

use -passes=reg2mem instead

llvm/include/llvm/InitializePasses.h

 void initializePruneEHPass(PassRegistry&);
 void initializeRABasicPass(PassRegistry&);
 void initializeRAGreedyPass(PassRegistry&);
 void initializeReachingDefAnalysisPass(PassRegistry&);
 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&);
 void initializeRegionOnlyPrinterPass(PassRegistry&);
 void initializeRegionOnlyViewerPass(PassRegistry&);
 void initializeRegionPrinterPass(PassRegistry&);
 void initializeRegionViewerPass(PassRegistry&);
 void initializeRegisterCoalescerPass(PassRegistry&);

llvm/include/llvm/Transforms/Scalar/Reg2Mem.h

+//===- 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

llvm/lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/Scalar/MakeGuardsExplicit.h"
 #include "llvm/Transforms/Scalar/MemCpyOptimizer.h"
 #include "llvm/Transforms/Scalar/MergeICmps.h"
 #include "llvm/Transforms/Scalar/MergedLoadStoreMotion.h"
 #include "llvm/Transforms/Scalar/NaryReassociate.h"
 #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"
 #include "llvm/Transforms/Scalar/Scalarizer.h"
 #include "llvm/Transforms/Scalar/SimpleLoopUnswitch.h"
 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
 #include "llvm/Transforms/Scalar/Sink.h"
 #include "llvm/Transforms/Scalar/SpeculateAroundPHIs.h"

llvm/lib/Passes/PassRegistry.def

 FUNCTION_PASS("print<regions>", RegionInfoPrinterPass(dbgs()))
 FUNCTION_PASS("print<scalar-evolution>", ScalarEvolutionPrinterPass(dbgs()))
 FUNCTION_PASS("print<stack-safety-local>", StackSafetyPrinterPass(dbgs()))
 // TODO: rename to print<foo> after NPM switch
 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())
 FUNCTION_PASS("sink", SinkingPass())
 FUNCTION_PASS("slp-vectorizer", SLPVectorizerPass())
 FUNCTION_PASS("slsr", StraightLineStrengthReducePass())
 FUNCTION_PASS("speculative-execution", SpeculativeExecutionPass())
 FUNCTION_PASS("spec-phis", SpeculateAroundPHIsPass())

llvm/lib/Transforms/Scalar/Reg2Mem.cpp

 // the inverse of PromoteMemoryToRegister.  By converting to loads, the only
 // values live across basic blocks are allocas and loads before phi nodes.
 // It is intended that this should make CFG hacking much easier.
 // To make later hacking easier, the entry block is split into two, such that
 // all introduced allocas and nothing else are in the entry block.
 //
 //===----------------------------------------------------------------------===//
 
+#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;
 
 #define DEBUG_TYPE "reg2mem"
 
 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;
-    }
+static bool valueEscapes(const Instruction &Inst) {
 
-    bool runOnFunction(Function &F) override;
-  };
-}
-
-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) &&
          "Entry block to function must not have predecessors!");
 
   // Find first non-alloca instruction and create insertion point. This is
   // safe if block is well-formed: it always have terminator, otherwise
   // we'll get and assertion.
static bool runPass(Function &F) {
   // Demote phi nodes
   NumPhisDemoted += WorkList.size();
   for (Instruction *I : WorkList)
     DemotePHIToStack(cast<PHINode>(I), AllocaInsertionPoint);
 
   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();
 }

llvm/lib/Transforms/Scalar/Scalar.cpp

void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeLowerWidenableConditionLegacyPassPass(Registry);
   initializeMemCpyOptLegacyPassPass(Registry);
   initializeMergeICmpsLegacyPassPass(Registry);
   initializeMergedLoadStoreMotionLegacyPassPass(Registry);
   initializeNaryReassociateLegacyPassPass(Registry);
   initializePartiallyInlineLibCallsLegacyPassPass(Registry);
   initializeReassociateLegacyPassPass(Registry);
   initializeRedundantDbgInstEliminationPass(Registry);
-  initializeRegToMemPass(Registry);
+  initializeRegToMemLegacyPass(Registry);
   initializeRewriteStatepointsForGCLegacyPassPass(Registry);
   initializeSCCPLegacyPassPass(Registry);
   initializeSROALegacyPassPass(Registry);
   initializeCFGSimplifyPassPass(Registry);
   initializeStructurizeCFGLegacyPassPass(Registry);
   initializeSimpleLoopUnswitchLegacyPassPass(Registry);
   initializeSinkingLegacyPassPass(Registry);
   initializeTailCallElimPass(Registry);

llvm/test/Transforms/Reg2Mem/crash.ll

-; 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()
 
 declare i32 @__gxx_personality_sj0(...)
 
 declare void @f2()