[PM] Separate the InstCombiner from its pass.

This creates a small internal pass which runs the InstCombiner over
a function. This is the hard part of porting InstCombine to the new pass
manager, as at this point none of the code in InstCombine has access to
a Pass object any longer.

The resulting interface for the InstCombiner is pretty terrible. I'm not
planning on leaving it that way. The key thing missing is that we need
to separate the worklist from the combiner a touch more. Once that's
done, it should be possible for *any* part of LLVM to just create
a worklist with instructions, populate it, and then combine it until
empty. The pass will just be the (obvious and important) special case of
doing that for an entire function body.

For now, this is the first increment of factoring to make all of this
work.

llvm-svn: 226618

2 files changed, 79 insertions, 49 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombine.h b/llvm/lib/Transforms/InstCombine/InstCombine.h
index f22b5b07b25..e404581bd91 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombine.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombine.h
@@ -104,8 +104,7 @@ public:
 /// combine them, as well as the pass infrastructure for running this as part
 /// of the LLVM pass pipeline.
 class LLVM_LIBRARY_VISIBILITY InstCombiner
-    : public FunctionPass,
-      public InstVisitor<InstCombiner, Instruction *> {
+    : public InstVisitor<InstCombiner, Instruction *> {
   AssumptionCache *AC;
   const DataLayout *DL;
   TargetLibraryInfo *TLI;
@@ -124,21 +123,16 @@ public:
   typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
   BuilderTy *Builder;
 
-  static char ID; // Pass identification, replacement for typeid
-  InstCombiner()
-      : FunctionPass(ID), DL(nullptr), DT(nullptr), LI(nullptr),
-        Builder(nullptr) {
+  InstCombiner() : DL(nullptr), DT(nullptr), LI(nullptr), Builder(nullptr) {
     MinimizeSize = false;
-    initializeInstCombinerPass(*PassRegistry::getPassRegistry());
   }
 
 public:
-  bool runOnFunction(Function &F) override;
+  bool run(Function &F, AssumptionCache *AC, const DataLayout *DL,
+           TargetLibraryInfo *TLI, DominatorTree *DT, LoopInfo *LI);
 
   bool DoOneIteration(Function &F, unsigned ItNum);
 
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
   AssumptionCache *getAssumptionCache() const { return AC; }
 
   const DataLayout *getDataLayout() const { return DL; }
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 5e9a22ca12e..a012be0669a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -72,33 +72,6 @@ STATISTIC(NumExpand,    "Number of expansions");
 STATISTIC(NumFactor   , "Number of factorizations");
 STATISTIC(NumReassoc  , "Number of reassociations");
 
-// Initialization Routines
-void llvm::initializeInstCombine(PassRegistry &Registry) {
-  initializeInstCombinerPass(Registry);
-}
-
-void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
-  initializeInstCombine(*unwrap(R));
-}
-
-char InstCombiner::ID = 0;
-INITIALIZE_PASS_BEGIN(InstCombiner, "instcombine",
-                "Combine redundant instructions", false, false)
-INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
-INITIALIZE_PASS_END(InstCombiner, "instcombine",
-                "Combine redundant instructions", false, false)
-
-void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesCFG();
-  AU.addRequired<AssumptionCacheTracker>();
-  AU.addRequired<TargetLibraryInfoWrapperPass>();
-  AU.addRequired<DominatorTreeWrapperPass>();
-  AU.addPreserved<DominatorTreeWrapperPass>();
-}
-
-
 Value *InstCombiner::EmitGEPOffset(User *GEP) {
   return llvm::EmitGEPOffset(Builder, *getDataLayout(), GEP);
 }
@@ -2965,17 +2938,19 @@ public:
 };
 }
 
-bool InstCombiner::runOnFunction(Function &F) {
-  if (skipOptnoneFunction(F))
-    return false;
-
-  AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
-  DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
-  DL = DLP ? &DLP->getDataLayout() : nullptr;
-  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-  auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
-  LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
-  TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+// FIXME: Passing all of the analyses here in the run method is ugly. We should
+// separate out the worklist from the combiner so that we can construct
+// a combiner once per function while re-using the storage of an external
+// worklist.
+bool InstCombiner::run(Function &F, AssumptionCache *AC, const DataLayout *DL,
+                       TargetLibraryInfo *TLI, DominatorTree *DT,
+                       LoopInfo *LI) {
+  // Set up our analysis pointers.
+  this->AC = AC;
+  this->DL = DL;
+  this->TLI = TLI;
+  this->DT = DT;
+  this->LI = LI;
 
   // Minimizing size?
   MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
@@ -3005,6 +2980,67 @@ bool InstCombiner::runOnFunction(Function &F) {
   return EverMadeChange;
 }
 
+namespace {
+/// \brief The legacy pass manager's instcombine pass.
+///
+/// This is a basic whole-function wrapper around the instcombine utility. It
+/// will try to combine all instructions in the function.
+class InstructionCombiningPass : public FunctionPass {
+  InstCombiner IC;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+
+  InstructionCombiningPass() : FunctionPass(ID) {
+    initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  bool runOnFunction(Function &F) override;
+};
+}
+
+void InstructionCombiningPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesCFG();
+  AU.addRequired<AssumptionCacheTracker>();
+  AU.addRequired<TargetLibraryInfoWrapperPass>();
+  AU.addRequired<DominatorTreeWrapperPass>();
+  AU.addPreserved<DominatorTreeWrapperPass>();
+}
+
+bool InstructionCombiningPass::runOnFunction(Function &F) {
+  if (skipOptnoneFunction(F))
+    return false;
+
+  auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+  auto *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+  auto *DL = DLP ? &DLP->getDataLayout() : nullptr;
+  auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
+  auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
+
+  return IC.run(F, &AC, DL, &TLI, &DT, LI);
+}
+
+char InstructionCombiningPass::ID = 0;
+INITIALIZE_PASS_BEGIN(InstructionCombiningPass, "instcombine",
+                      "Combine redundant instructions", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(InstructionCombiningPass, "instcombine",
+                    "Combine redundant instructions", false, false)
+
+// Initialization Routines
+void llvm::initializeInstCombine(PassRegistry &Registry) {
+  initializeInstructionCombiningPassPass(Registry);
+}
+
+void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
+  initializeInstructionCombiningPassPass(*unwrap(R));
+}
+
 FunctionPass *llvm::createInstructionCombiningPass() {
-  return new InstCombiner();
+  return new InstructionCombiningPass();
 }