[PM] Port instcombine to the new pass manager!

This is exciting as this is a much more involved port. This is
a complex, existing transformation pass. All of the core logic is shared
between both old and new pass managers. Only the access to the analyses
is separate because the actual techniques are separate. This also uses
a bunch of different and interesting analyses and is the first time
where we need to use an analysis across an IR layer.

This also paves the way to expose instcombine utility functions. I've
got a static function that implements the core pass logic over
a function which might be mildly interesting, but more interesting is
likely exposing a routine which just uses instructions *already in* the
worklist and combines until empty.

I've switched one of my favorite instcombine tests to run with both as
well to make sure this keeps working.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226987 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/InstCombine/InstCombine.h

@@ -0,0 +1,46 @@
+//===- InstCombine.h - InstCombine pass -------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file provides the primary interface to the instcombine pass. This pass
+/// is suitable for use in the new pass manager. For a pass that works with the
+/// legacy pass manager, please look for \c createInstructionCombiningPass() in
+/// Scalar.h.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
+#define LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
+
+#include "llvm/IR/Function.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
+
+namespace llvm {
+
+class InstCombinePass {
+  InstCombineWorklist Worklist;
+
+public:
+  static StringRef name() { return "InstCombinePass"; }
+
+  // Explicitly define constructors for MSVC.
+  InstCombinePass() {}
+  InstCombinePass(InstCombinePass &&Arg) : Worklist(std::move(Arg.Worklist)) {}
+  InstCombinePass &operator=(InstCombinePass &&RHS) {
+    Worklist = std::move(RHS.Worklist);
+    return *this;
+  }
+
+  PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
+};
+
+}
+
+#endif

include/llvm/Transforms/InstCombine/InstCombineWorklist.h

@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
-#define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
+#ifndef LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
+#define LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
@@ -32,6 +32,15 @@ class LLVM_LIBRARY_VISIBILITY InstCombineWorklist {
 public:
   InstCombineWorklist() {}
 
+  InstCombineWorklist(InstCombineWorklist &&Arg)
+      : Worklist(std::move(Arg.Worklist)),
+        WorklistMap(std::move(Arg.WorklistMap)) {}
+  InstCombineWorklist &operator=(InstCombineWorklist &&RHS) {
+    Worklist = std::move(RHS.Worklist);
+    WorklistMap = std::move(RHS.WorklistMap);
+    return *this;
+  }
+
   bool isEmpty() const { return Worklist.empty(); }
 
   /// Add - Add the specified instruction to the worklist if it isn't already

lib/Transforms/InstCombine/InstCombineInternal.h

@@ -15,7 +15,6 @@
 #ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
 #define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
 
-#include "InstCombineWorklist.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/TargetFolder.h"
@@ -27,6 +26,7 @@
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/Pass.h"
+#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
 
 #define DEBUG_TYPE "instcombine"
 

lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -33,7 +33,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "InstCombineInternal.h"
 #include "llvm-c/Initialization.h"
 #include "llvm/ADT/SmallPtrSet.h"
@@ -45,6 +45,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/DataLayout.h"
@@ -55,7 +56,7 @@
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <algorithm>
 #include <climits>
@@ -2922,6 +2923,66 @@ static bool prepareICWorklistFromFunction(Function &F, const DataLayout *DL,
   return MadeIRChange;
 }
 
+static bool combineInstructionsOverFunction(
+    Function &F, InstCombineWorklist &Worklist, AssumptionCache &AC,
+    TargetLibraryInfo &TLI, DominatorTree &DT, const DataLayout *DL = nullptr,
+    LoopInfo *LI = nullptr) {
+  // Minimizing size?
+  bool MinimizeSize = F.getAttributes().hasAttribute(
+      AttributeSet::FunctionIndex, Attribute::MinSize);
+
+  /// Builder - This is an IRBuilder that automatically inserts new
+  /// instructions into the worklist when they are created.
+  IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
+      F.getContext(), TargetFolder(DL), InstCombineIRInserter(Worklist, &AC));
+
+  // Lower dbg.declare intrinsics otherwise their value may be clobbered
+  // by instcombiner.
+  bool DbgDeclaresChanged = LowerDbgDeclare(F);
+
+  // Iterate while there is work to do.
+  int Iteration = 0;
+  for (;;) {
+    ++Iteration;
+    DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+                 << F.getName() << "\n");
+
+    bool Changed = false;
+    if (prepareICWorklistFromFunction(F, DL, &TLI, Worklist))
+      Changed = true;
+
+    InstCombiner IC(Worklist, &Builder, MinimizeSize, &AC, &TLI, &DT, DL, LI);
+    if (IC.run())
+      Changed = true;
+
+    if (!Changed)
+      break;
+  }
+
+  return DbgDeclaresChanged || Iteration > 1;
+}
+
+PreservedAnalyses InstCombinePass::run(Function &F,
+                                       AnalysisManager<Function> *AM) {
+  auto *DL = F.getParent()->getDataLayout();
+
+  auto &AC = AM->getResult<AssumptionAnalysis>(F);
+  auto &DT = AM->getResult<DominatorTreeAnalysis>(F);
+  auto &TLI = AM->getResult<TargetLibraryAnalysis>(F);
+
+  auto *LI = AM->getCachedResult<LoopAnalysis>(F);
+
+  if (!combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, DL, LI))
+    // No changes, all analyses are preserved.
+    return PreservedAnalyses::all();
+
+  // Mark all the analyses that instcombine updates as preserved.
+  // FIXME: Need a way to preserve CFG analyses here!
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  return PA;
+}
+
 namespace {
 /// \brief The legacy pass manager's instcombine pass.
 ///
@@ -2954,10 +3015,6 @@ bool InstructionCombiningPass::runOnFunction(Function &F) {
   if (skipOptnoneFunction(F))
     return false;
 
-  // Lower dbg.declare intrinsics otherwise their value may be clobbered
-  // by instcombiner.
-  bool DbgDeclaresChanged = LowerDbgDeclare(F);
-
   // Required analyses.
   auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
   auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
@@ -2969,35 +3026,7 @@ bool InstructionCombiningPass::runOnFunction(Function &F) {
   auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
   auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
 
-  // Minimizing size?
-  bool MinimizeSize = F.getAttributes().hasAttribute(
-      AttributeSet::FunctionIndex, Attribute::MinSize);
-
-  /// Builder - This is an IRBuilder that automatically inserts new
-  /// instructions into the worklist when they are created.
-  IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
-      F.getContext(), TargetFolder(DL), InstCombineIRInserter(Worklist, &AC));
-
-  // Iterate while there is work to do.
-  int Iteration = 0;
-  for (;;) {
-    ++Iteration;
-    DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
-                 << F.getName() << "\n");
-
-    bool Changed = false;
-    if (prepareICWorklistFromFunction(F, DL, &TLI, Worklist))
-      Changed = true;
-
-    InstCombiner IC(Worklist, &Builder, MinimizeSize, &AC, &TLI, &DT, DL, LI);
-    if (IC.run())
-      Changed = true;
-
-    if (!Changed)
-      break;
-  }
-
-  return DbgDeclaresChanged || Iteration > 1;
+  return combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, DL, LI);
 }
 
 char InstructionCombiningPass::ID = 0;

test/Transforms/InstCombine/load.ll

@@ -1,4 +1,5 @@
 ; RUN: opt -instcombine -S < %s | FileCheck %s
+; RUN: opt -passes=instcombine -S < %s | FileCheck %s
 
 ; This test makes sure that these instructions are properly eliminated.
 

tools/opt/PassRegistry.def

@@ -60,6 +60,7 @@ FUNCTION_ANALYSIS("targetlibinfo", TargetLibraryAnalysis())
 #ifndef FUNCTION_PASS
 #define FUNCTION_PASS(NAME, CREATE_PASS)
 #endif
+FUNCTION_PASS("instcombine", InstCombinePass())
 FUNCTION_PASS("invalidate<all>", InvalidateAllAnalysesPass())
 FUNCTION_PASS("no-op-function", NoOpFunctionPass())
 FUNCTION_PASS("print", PrintFunctionPass(dbgs()))

tools/opt/Passes.cpp

@@ -25,6 +25,7 @@
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
 
 using namespace llvm;