[PM] Port MergedLoadStoreMotion to the new pass manager, take two.

This is indeed a much cleaner approach (thanks to Daniel Berlin
for pointing out), and also David/Sean for review.

Differential Revision:  http://reviews.llvm.org/D21454


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273032 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/InitializePasses.h

@@ -226,7 +226,7 @@ void initializeMemoryDependenceWrapperPassPass(PassRegistry&);
 void initializeMemorySSAWrapperPassPass(PassRegistry&);
 void initializeMemorySanitizerPass(PassRegistry&);
 void initializeMergeFunctionsPass(PassRegistry&);
-void initializeMergedLoadStoreMotionPass(PassRegistry &);
+void initializeMergedLoadStoreMotionLegacyPassPass(PassRegistry &);
 void initializeMetaRenamerPass(PassRegistry&);
 void initializeModuleDebugInfoPrinterPass(PassRegistry&);
 void initializeModuleSummaryIndexWrapperPassPass(PassRegistry &);

include/llvm/Transforms/Scalar/MergedLoadStoreMotion.h

@@ -0,0 +1,39 @@
+//===- MergedLoadStoreMotion.h - merge and hoist/sink load/stores ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//! \file
+//! \brief This pass performs merges of loads and stores on both sides of a
+//  diamond (hammock). It hoists the loads and sinks the stores.
+//
+// The algorithm iteratively hoists two loads to the same address out of a
+// diamond (hammock) and merges them into a single load in the header. Similar
+// it sinks and merges two stores to the tail block (footer). The algorithm
+// iterates over the instructions of one side of the diamond and attempts to
+// find a matching load/store on the other side. It hoists / sinks when it
+// thinks it safe to do so.  This optimization helps with eg. hiding load
+// latencies, triggering if-conversion, and reducing static code size.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
+#define LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
+
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+class MergedLoadStoreMotionPass
+    : public PassInfoMixin<MergedLoadStoreMotionPass> {
+public:
+  PreservedAnalyses run(Function &F, AnalysisManager<Function> &AM);
+};
+
+}
+
+#endif // LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H

lib/LTO/LTOCodeGenerator.cpp

@@ -123,7 +123,7 @@ void LTOCodeGenerator::initializeLTOPasses() {
   initializeReversePostOrderFunctionAttrsLegacyPassPass(R);
   initializeGlobalsAAWrapperPassPass(R);
   initializeLICMPass(R);
-  initializeMergedLoadStoreMotionPass(R);
+  initializeMergedLoadStoreMotionLegacyPassPass(R);
   initializeGVNLegacyPassPass(R);
   initializeMemCpyOptLegacyPassPass(R);
   initializeDCELegacyPassPass(R);

lib/Passes/PassBuilder.cpp

@@ -83,6 +83,7 @@
 #include "llvm/Transforms/Scalar/LowerAtomic.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Scalar/MemCpyOptimizer.h"
+#include "llvm/Transforms/Scalar/MergedLoadStoreMotion.h"
 #include "llvm/Transforms/Scalar/PartiallyInlineLibCalls.h"
 #include "llvm/Transforms/Scalar/Reassociate.h"
 #include "llvm/Transforms/Scalar/SCCP.h"

lib/Passes/PassRegistry.def

@@ -134,6 +134,7 @@ FUNCTION_PASS("guard-widening", GuardWideningPass())
 FUNCTION_PASS("gvn", GVN())
 FUNCTION_PASS("mem2reg", PromotePass())
 FUNCTION_PASS("memcpyopt", MemCpyOptPass())
+FUNCTION_PASS("mldst-motion", MergedLoadStoreMotionPass())
 FUNCTION_PASS("jump-threading", JumpThreadingPass())
 FUNCTION_PASS("partially-inline-libcalls", PartiallyInlineLibCallsPass())
 FUNCTION_PASS("lcssa", LCSSAPass())

lib/Transforms/Scalar/MergedLoadStoreMotion.cpp

@@ -72,6 +72,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/MergedLoadStoreMotion.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/CFG.h"
@@ -95,32 +96,20 @@ using namespace llvm;
 //===----------------------------------------------------------------------===//
 //                         MergedLoadStoreMotion Pass
 //===----------------------------------------------------------------------===//
+class MergedLoadStoreMotion {
+  MemoryDependenceResults *MD = nullptr;
+  AliasAnalysis *AA = nullptr;
 
-namespace {
-class MergedLoadStoreMotion : public FunctionPass {
-  AliasAnalysis *AA;
-  MemoryDependenceResults *MD;
+  // The mergeLoad/Store algorithms could have Size0 * Size1 complexity,
+  // where Size0 and Size1 are the #instructions on the two sides of
+  // the diamond. The constant chosen here is arbitrary. Compiler Time
+  // Control is enforced by the check Size0 * Size1 < MagicCompileTimeControl.
+  const int MagicCompileTimeControl = 250;
 
 public:
-  static char ID; // Pass identification, replacement for typeid
-  MergedLoadStoreMotion()
-      : FunctionPass(ID), MD(nullptr), MagicCompileTimeControl(250) {
-    initializeMergedLoadStoreMotionPass(*PassRegistry::getPassRegistry());
-  }
-
-  bool runOnFunction(Function &F) override;
+  bool run(Function &F, MemoryDependenceResults *MD, AliasAnalysis &AA);
 
 private:
-  // This transformation requires dominator postdominator info
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
-    AU.addRequired<AAResultsWrapperPass>();
-    AU.addPreserved<GlobalsAAWrapperPass>();
-    AU.addPreserved<MemoryDependenceWrapperPass>();
-  }
-
-  // Helper routines
-
   ///
   /// \brief Remove instruction from parent and update memory dependence
   /// analysis.
@@ -145,30 +134,8 @@ private:
                                  const Instruction &End, MemoryLocation Loc);
   bool sinkStore(BasicBlock *BB, StoreInst *SinkCand, StoreInst *ElseInst);
   bool mergeStores(BasicBlock *BB);
-  // The mergeLoad/Store algorithms could have Size0 * Size1 complexity,
-  // where Size0 and Size1 are the #instructions on the two sides of
-  // the diamond. The constant chosen here is arbitrary. Compiler Time
-  // Control is enforced by the check Size0 * Size1 < MagicCompileTimeControl.
-  const int MagicCompileTimeControl;
 };
 
-char MergedLoadStoreMotion::ID = 0;
-} // anonymous namespace
-
-///
-/// \brief createMergedLoadStoreMotionPass - The public interface to this file.
-///
-FunctionPass *llvm::createMergedLoadStoreMotionPass() {
-  return new MergedLoadStoreMotion();
-}
-
-INITIALIZE_PASS_BEGIN(MergedLoadStoreMotion, "mldst-motion",
-                      "MergedLoadStoreMotion", false, false)
-INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
-INITIALIZE_PASS_END(MergedLoadStoreMotion, "mldst-motion",
-                    "MergedLoadStoreMotion", false, false)
-
 ///
 /// \brief Remove instruction from parent and update memory dependence analysis.
 ///
@@ -552,16 +519,10 @@ bool MergedLoadStoreMotion::mergeStores(BasicBlock *T) {
   return MergedStores;
 }
 
-///
-/// \brief Run the transformation for each function
-///
-bool MergedLoadStoreMotion::runOnFunction(Function &F) {
-  if (skipFunction(F))
-    return false;
-
-  auto *MDWP = getAnalysisIfAvailable<MemoryDependenceWrapperPass>();
-  MD = MDWP ? &MDWP->getMemDep() : nullptr;
-  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+bool MergedLoadStoreMotion::run(Function &F, MemoryDependenceResults *MD,
+                                AliasAnalysis &AA) {
+  this->MD = MD;
+  this->AA = &AA;
 
   bool Changed = false;
   DEBUG(dbgs() << "Instruction Merger\n");
@@ -580,3 +541,67 @@ bool MergedLoadStoreMotion::runOnFunction(Function &F) {
   }
   return Changed;
 }
+
+namespace {
+class MergedLoadStoreMotionLegacyPass : public FunctionPass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  MergedLoadStoreMotionLegacyPass() : FunctionPass(ID) {
+    initializeMergedLoadStoreMotionLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+
+  ///
+  /// \brief Run the transformation for each function
+  ///
+  bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+    MergedLoadStoreMotion Impl;
+    auto *MDWP = getAnalysisIfAvailable<MemoryDependenceWrapperPass>();
+    return Impl.run(F, MDWP ? &MDWP->getMemDep() : nullptr,
+                    getAnalysis<AAResultsWrapperPass>().getAAResults());
+  }
+
+private:
+  // This transformation requires dominator postdominator info
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    AU.addRequired<AAResultsWrapperPass>();
+    AU.addPreserved<GlobalsAAWrapperPass>();
+    AU.addPreserved<MemoryDependenceWrapperPass>();
+  }
+};
+
+char MergedLoadStoreMotionLegacyPass::ID = 0;
+} // anonymous namespace
+
+///
+/// \brief createMergedLoadStoreMotionPass - The public interface to this file.
+///
+FunctionPass *llvm::createMergedLoadStoreMotionPass() {
+  return new MergedLoadStoreMotionLegacyPass();
+}
+
+INITIALIZE_PASS_BEGIN(MergedLoadStoreMotionLegacyPass, "mldst-motion",
+                      "MergedLoadStoreMotion", false, false)
+INITIALIZE_PASS_DEPENDENCY(MemoryDependenceWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
+INITIALIZE_PASS_END(MergedLoadStoreMotionLegacyPass, "mldst-motion",
+                    "MergedLoadStoreMotion", false, false)
+
+PreservedAnalyses
+MergedLoadStoreMotionPass::run(Function &F, AnalysisManager<Function> &AM) {
+  MergedLoadStoreMotion Impl;
+  auto *MD = AM.getCachedResult<MemoryDependenceAnalysis>(F);
+  auto &AA = AM.getResult<AAManager>(F);
+  if (!Impl.run(F, MD, AA))
+    return PreservedAnalyses::all();
+
+  // FIXME: This pass should also 'preserve the CFG'.
+  // The new pass manager has currently no way to do it.
+  PreservedAnalyses PA;
+  PA.preserve<GlobalsAA>();
+  PA.preserve<MemoryDependenceAnalysis>();
+  return PA;
+}

lib/Transforms/Scalar/Scalar.cpp

@@ -65,7 +65,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeLowerExpectIntrinsicPass(Registry);
   initializeLowerGuardIntrinsicPass(Registry);
   initializeMemCpyOptLegacyPassPass(Registry);
-  initializeMergedLoadStoreMotionPass(Registry);
+  initializeMergedLoadStoreMotionLegacyPassPass(Registry);
   initializeNaryReassociatePass(Registry);
   initializePartiallyInlineLibCallsLegacyPassPass(Registry);
   initializeReassociateLegacyPassPass(Registry);

test/Transforms/InstMerge/exceptions.ll

@@ -1,4 +1,7 @@
 ; RUN: opt -basicaa -memdep -mldst-motion -S < %s | FileCheck %s
+; RUN: opt -aa-pipeline=basic-aa -passes='require<memdep>',mldst-motion \
+; RUN:   -S < %s | FileCheck %s
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"