[PM] Port SimplifyCFG to the new pass manager.

This should be sufficient to replace the initial (minor) function pass
pipeline in Clang with the new pass manager. I'll probably add an (off
by default) flag to do that just to ensure we can get extra testing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227726 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/Scalar/SimplifyCFG.h

@@ -0,0 +1,46 @@
+//===- SimplifyCFG.h - Simplify and canonicalize the CFG --------*- 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 interface for the pass responsible for both
+/// simplifying and canonicalizing the CFG.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_SIMPLIFYCFG_H
+#define LLVM_TRANSFORMS_SCALAR_SIMPLIFYCFG_H
+
+#include "llvm/IR/Function.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// \brief A pass to simplify and canonicalize the CFG of a function.
+///
+/// This pass iteratively simplifies the entire CFG of a function, removing
+/// unnecessary control flows and bringing it into the canonical form expected
+/// by the rest of the mid-level optimizer.
+class SimplifyCFGPass {
+  int BonusInstThreshold;
+
+public:
+  static StringRef name() { return "SimplifyCFGPass"; }
+
+  /// \brief Construct a pass with the default thresholds.
+  SimplifyCFGPass();
+
+  /// \brief Construct a pass with a specific bonus threshold.
+  SimplifyCFGPass(int BonusInstThreshold);
+
+  /// \brief Run the pass over the function.
+  PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
+};
+
+}
+
+#endif

lib/Transforms/Scalar/SimplifyCFGPass.cpp

@@ -21,7 +21,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/SimplifyCFG.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -37,6 +37,7 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Scalar.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "simplifycfg"
@@ -47,36 +48,6 @@ UserBonusInstThreshold("bonus-inst-threshold", cl::Hidden, cl::init(1),
 
 STATISTIC(NumSimpl, "Number of blocks simplified");
 
-namespace {
-struct CFGSimplifyPass : public FunctionPass {
-  static char ID; // Pass identification, replacement for typeid
-  unsigned BonusInstThreshold;
-  CFGSimplifyPass(int T = -1) : FunctionPass(ID) {
-    BonusInstThreshold = (T == -1) ? UserBonusInstThreshold : unsigned(T);
-    initializeCFGSimplifyPassPass(*PassRegistry::getPassRegistry());
-  }
-  bool runOnFunction(Function &F) override;
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.addRequired<AssumptionCacheTracker>();
-    AU.addRequired<TargetTransformInfoWrapperPass>();
-  }
-};
-}
-
-char CFGSimplifyPass::ID = 0;
-INITIALIZE_PASS_BEGIN(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
-                      false)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_END(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
-                    false)
-
-// Public interface to the CFGSimplification pass
-FunctionPass *llvm::createCFGSimplificationPass(int Threshold) {
-  return new CFGSimplifyPass(Threshold);
-}
-
 /// mergeEmptyReturnBlocks - If we have more than one empty (other than phi
 /// node) return blocks, merge them together to promote recursive block merging.
 static bool mergeEmptyReturnBlocks(Function &F) {
@@ -176,19 +147,9 @@ static bool iterativelySimplifyCFG(Function &F, const TargetTransformInfo &TTI,
   return Changed;
 }
 
-// It is possible that we may require multiple passes over the code to fully
-// simplify the CFG.
-//
-bool CFGSimplifyPass::runOnFunction(Function &F) {
-  if (skipOptnoneFunction(F))
-    return false;
-
-  AssumptionCache *AC =
-      &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
-  const TargetTransformInfo &TTI =
-      getAnalysis<TargetTransformInfoWrapperPass>().getTTI();
-  DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
-  const DataLayout *DL = DLP ? &DLP->getDataLayout() : nullptr;
+static bool simplifyFunctionCFG(Function &F, const TargetTransformInfo &TTI,
+                                const DataLayout *DL, AssumptionCache *AC,
+                                int BonusInstThreshold) {
   bool EverChanged = removeUnreachableBlocks(F);
   EverChanged |= mergeEmptyReturnBlocks(F);
   EverChanged |= iterativelySimplifyCFG(F, TTI, DL, AC, BonusInstThreshold);
@@ -211,3 +172,63 @@ bool CFGSimplifyPass::runOnFunction(Function &F) {
 
   return true;
 }
+
+SimplifyCFGPass::SimplifyCFGPass()
+    : BonusInstThreshold(UserBonusInstThreshold) {}
+
+SimplifyCFGPass::SimplifyCFGPass(int BonusInstThreshold)
+    : BonusInstThreshold(BonusInstThreshold) {}
+
+PreservedAnalyses SimplifyCFGPass::run(Function &F,
+                                       AnalysisManager<Function> *AM) {
+  auto *DL = F.getParent()->getDataLayout();
+  auto &TTI = AM->getResult<TargetIRAnalysis>(F);
+  auto &AC = AM->getResult<AssumptionAnalysis>(F);
+
+  if (!simplifyFunctionCFG(F, TTI, DL, &AC, BonusInstThreshold))
+    return PreservedAnalyses::none();
+
+  return PreservedAnalyses::all();
+}
+
+namespace {
+struct CFGSimplifyPass : public FunctionPass {
+  static char ID; // Pass identification, replacement for typeid
+  unsigned BonusInstThreshold;
+  CFGSimplifyPass(int T = -1) : FunctionPass(ID) {
+    BonusInstThreshold = (T == -1) ? UserBonusInstThreshold : unsigned(T);
+    initializeCFGSimplifyPassPass(*PassRegistry::getPassRegistry());
+  }
+  bool runOnFunction(Function &F) override {
+    if (skipOptnoneFunction(F))
+      return false;
+
+    AssumptionCache *AC =
+        &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+    const TargetTransformInfo &TTI =
+        getAnalysis<TargetTransformInfoWrapperPass>().getTTI();
+    DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+    const DataLayout *DL = DLP ? &DLP->getDataLayout() : nullptr;
+    return simplifyFunctionCFG(F, TTI, DL, AC, BonusInstThreshold);
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<TargetTransformInfoWrapperPass>();
+  }
+};
+}
+
+char CFGSimplifyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
+                      false)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_END(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
+                    false)
+
+// Public interface to the CFGSimplification pass
+FunctionPass *llvm::createCFGSimplificationPass(int Threshold) {
+  return new CFGSimplifyPass(Threshold);
+}
+

test/Transforms/SimplifyCFG/basictest.ll

@@ -1,6 +1,7 @@
 ; Test CFG simplify removal of branch instructions.
 ;
 ; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -passes=simplify-cfg -S | FileCheck %s
 
 define void @test1() {
         br label %1

tools/opt/PassRegistry.def

@@ -71,6 +71,7 @@ FUNCTION_PASS("print", PrintFunctionPass(dbgs()))
 FUNCTION_PASS("print<assumptions>", AssumptionPrinterPass(dbgs()))
 FUNCTION_PASS("print<domtree>", DominatorTreePrinterPass(dbgs()))
 FUNCTION_PASS("print<loops>", LoopPrinterPass(dbgs()))
+FUNCTION_PASS("simplify-cfg", SimplifyCFGPass())
 FUNCTION_PASS("verify", VerifierPass())
 FUNCTION_PASS("verify<domtree>", DominatorTreeVerifierPass())
 #undef FUNCTION_PASS

tools/opt/Passes.cpp

@@ -30,6 +30,7 @@
 #include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "llvm/Transforms/Scalar/EarlyCSE.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
+#include "llvm/Transforms/Scalar/SimplifyCFG.h"
 
 using namespace llvm;