[NPM] Port -mergereturn to NPM

[aeubanks]

llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp

125

this won't run unifyReturnBlocks() if unifyUnreachableBlocks() returns true, is that expected?

[TaWeiTu]

llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp

125

Oh, that was stupid. Thanks for pointing it out!

[aeubanks]

llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp

128

I like using PreservedAnalyses::none() better, it's more explicit.

[TaWeiTu]

Thanks for reviewing! Could you do me a favor of committing this and D89774 for me? (with --author="Ta-Wei Tu <[e-mail]>)

[aeubanks]

Done for this one, could you rebase the other one?

llvm/include/llvm/InitializePasses.h

 void initializeTailDuplicatePass(PassRegistry&);
 void initializeTargetLibraryInfoWrapperPassPass(PassRegistry&);
 void initializeTargetPassConfigPass(PassRegistry&);
 void initializeTargetTransformInfoWrapperPassPass(PassRegistry&);
 void initializeThreadSanitizerLegacyPassPass(PassRegistry&);
 void initializeTwoAddressInstructionPassPass(PassRegistry&);
 void initializeTypeBasedAAWrapperPassPass(PassRegistry&);
 void initializeTypePromotionPass(PassRegistry&);
-void initializeUnifyFunctionExitNodesPass(PassRegistry&);
+void initializeUnifyFunctionExitNodesLegacyPassPass(PassRegistry &);
 void initializeUnifyLoopExitsPass(PassRegistry &);
 void initializeUnpackMachineBundlesPass(PassRegistry&);
 void initializeUnreachableBlockElimLegacyPassPass(PassRegistry&);
 void initializeUnreachableMachineBlockElimPass(PassRegistry&);
 void initializeVectorCombineLegacyPassPass(PassRegistry&);
 void initializeVerifierLegacyPassPass(PassRegistry&);
 void initializeVirtRegMapPass(PassRegistry&);
 void initializeVirtRegRewriterPass(PassRegistry&);

llvm/include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h

 //===-- UnifyFunctionExitNodes.h - Ensure fn's have one return --*- 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 pass is used to ensure that functions have at most one return and one
 // unreachable instruction in them.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H
 #define LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H
 
+#include "llvm/IR/PassManager.h"
 #include "llvm/Pass.h"
 
 namespace llvm {
 
 class BasicBlock;
 
-class UnifyFunctionExitNodes : public FunctionPass {
-  bool unifyUnreachableBlocks(Function &F);
-  bool unifyReturnBlocks(Function &F);
-
+class UnifyFunctionExitNodesLegacyPass : public FunctionPass {
 public:
   static char ID; // Pass identification, replacement for typeid
-  UnifyFunctionExitNodes();
+  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:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H

llvm/lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/Utils/LowerInvoke.h"
 #include "llvm/Transforms/Utils/LowerSwitch.h"
 #include "llvm/Transforms/Utils/Mem2Reg.h"
 #include "llvm/Transforms/Utils/MetaRenamer.h"
 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
 #include "llvm/Transforms/Utils/StripGCRelocates.h"
 #include "llvm/Transforms/Utils/StripNonLineTableDebugInfo.h"
 #include "llvm/Transforms/Utils/SymbolRewriter.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
 #include "llvm/Transforms/Vectorize/LoadStoreVectorizer.h"
 #include "llvm/Transforms/Vectorize/LoopVectorize.h"
 #include "llvm/Transforms/Vectorize/SLPVectorizer.h"
 #include "llvm/Transforms/Vectorize/VectorCombine.h"
 
 using namespace llvm;
 
 static cl::opt<unsigned> MaxDevirtIterations("pm-max-devirt-iterations",

llvm/lib/Passes/PassRegistry.def

 FUNCTION_PASS("loop-simplify", LoopSimplifyPass())
 FUNCTION_PASS("loop-sink", LoopSinkPass())
 FUNCTION_PASS("loop-unroll-and-jam", LoopUnrollAndJamPass())
 FUNCTION_PASS("lowerinvoke", LowerInvokePass())
 FUNCTION_PASS("lowerswitch", LowerSwitchPass())
 FUNCTION_PASS("mem2reg", PromotePass())
 FUNCTION_PASS("memcpyopt", MemCpyOptPass())
 FUNCTION_PASS("mergeicmps", MergeICmpsPass())
+FUNCTION_PASS("mergereturn", UnifyFunctionExitNodesPass())
 FUNCTION_PASS("nary-reassociate", NaryReassociatePass())
 FUNCTION_PASS("newgvn", NewGVNPass())
 FUNCTION_PASS("jump-threading", JumpThreadingPass())
 FUNCTION_PASS("partially-inline-libcalls", PartiallyInlineLibCallsPass())
 FUNCTION_PASS("lcssa", LCSSAPass())
 FUNCTION_PASS("loop-data-prefetch", LoopDataPrefetchPass())
 FUNCTION_PASS("loop-load-elim", LoopLoadEliminationPass())
 FUNCTION_PASS("loop-fusion", LoopFusePass())

llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp

 #include "llvm/IR/BasicBlock.h"
 #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 UnifyFunctionExitNodes::ID = 0;
+char UnifyFunctionExitNodesLegacyPass::ID = 0;
 
-UnifyFunctionExitNodes::UnifyFunctionExitNodes() : FunctionPass(ID) {
-  initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
+UnifyFunctionExitNodesLegacyPass::UnifyFunctionExitNodesLegacyPass()
+    : FunctionPass(ID) {
+  initializeUnifyFunctionExitNodesLegacyPassPass(
+      *PassRegistry::getPassRegistry());
 }
 
-INITIALIZE_PASS(UnifyFunctionExitNodes, "mergereturn",
+INITIALIZE_PASS(UnifyFunctionExitNodesLegacyPass, "mergereturn",
                 "Unify function exit nodes", false, false)
 
 Pass *llvm::createUnifyFunctionExitNodesPass() {
-  return new UnifyFunctionExitNodes();
+  return new UnifyFunctionExitNodesLegacyPass();
 }
 
-void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
+void UnifyFunctionExitNodesLegacyPass::getAnalysisUsage(
+    AnalysisUsage &AU) const {
   // We preserve the non-critical-edgeness property
   AU.addPreservedID(BreakCriticalEdgesID);
   // This is a cluster of orthogonal Transforms
   AU.addPreservedID(LowerSwitchID);
 }
 
-bool UnifyFunctionExitNodes::unifyUnreachableBlocks(Function &F) {
-  std::vector<BasicBlock*> UnreachableBlocks;
+namespace {
+
+bool unifyUnreachableBlocks(Function &F) {
+  std::vector<BasicBlock *> UnreachableBlocks;
 
   for (BasicBlock &I : F)
     if (isa<UnreachableInst>(I.getTerminator()))
       UnreachableBlocks.push_back(&I);
 
   if (UnreachableBlocks.size() <= 1)
     return false;
 
   BasicBlock *UnreachableBlock =
       BasicBlock::Create(F.getContext(), "UnifiedUnreachableBlock", &F);
   new UnreachableInst(F.getContext(), UnreachableBlock);
 
   for (BasicBlock *BB : UnreachableBlocks) {
     BB->getInstList().pop_back(); // Remove the unreachable inst.
     BranchInst::Create(UnreachableBlock, BB);
   }
 
   return true;
 }
 
-bool UnifyFunctionExitNodes::unifyReturnBlocks(Function &F) {
+bool unifyReturnBlocks(Function &F) {
   std::vector<BasicBlock *> ReturningBlocks;
 
   for (BasicBlock &I : F)
     if (isa<ReturnInst>(I.getTerminator()))
       ReturningBlocks.push_back(&I);
 
   if (ReturningBlocks.size() <= 1)
     return false;
if (PN)
       PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
 
     BB->getInstList().pop_back();  // Remove the return insn
     BranchInst::Create(NewRetBlock, BB);
   }
 
   return true;
 }
+} // 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 UnifyFunctionExitNodes::runOnFunction(Function &F) {
+bool UnifyFunctionExitNodesLegacyPass::runOnFunction(Function &F) {
   bool Changed = false;
   Changed |= unifyUnreachableBlocks(F);
   Changed |= unifyReturnBlocks(F);
   return Changed;
 }
+
+PreservedAnalyses UnifyFunctionExitNodesPass::run(Function &F,
+                                                  FunctionAnalysisManager &AM) {
+  if (!unifyUnreachableBlocks(F) && !unifyReturnBlocks(F))
+    return PreservedAnalyses::all();
+  return PreservedAnalyses();
+}

llvm/lib/Transforms/Utils/Utils.cpp

void llvm::initializeTransformUtils(PassRegistry &Registry) {
   initializeLCSSAWrapperPassPass(Registry);
   initializeLibCallsShrinkWrapLegacyPassPass(Registry);
   initializeLoopSimplifyPass(Registry);
   initializeLowerInvokeLegacyPassPass(Registry);
   initializeLowerSwitchLegacyPassPass(Registry);
   initializeNameAnonGlobalLegacyPassPass(Registry);
   initializePromoteLegacyPassPass(Registry);
   initializeStripNonLineTableDebugLegacyPassPass(Registry);
-  initializeUnifyFunctionExitNodesPass(Registry);
+  initializeUnifyFunctionExitNodesLegacyPassPass(Registry);
   initializeMetaRenamerPass(Registry);
   initializeStripGCRelocatesLegacyPass(Registry);
   initializePredicateInfoPrinterLegacyPassPass(Registry);
   initializeInjectTLIMappingsLegacyPass(Registry);
   initializeFixIrreduciblePass(Registry);
   initializeUnifyLoopExitsPass(Registry);
   initializeUniqueInternalLinkageNamesLegacyPassPass(Registry);
 }

llvm/test/Transforms/UnifyFunctionExitNodes/unreachable-blocks-status.ll

 ; RUN: opt -mergereturn -enable-new-pm=0 -S < %s | FileCheck %s
+; RUN: opt -passes='break-crit-edges,lowerswitch,mergereturn' -S < %s | FileCheck %s
 
 ; The pass did previously not report the correct Modified status in the case
 ; where a function had at most one return block, and an unified unreachable
 ; block was created. This was caught by the pass return status check that is
 ; hidden under EXPENSIVE_CHECKS.
 
 ; CHECK: for.foo.body2:
 ; CHECK-NEXT: br label %UnifiedUnreachableBlock