1 files changed, 124 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopRotation.cpp b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
new file mode 100644
index 000000000000..94517996df39
--- /dev/null
+++ b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
@@ -0,0 +1,124 @@
+//===- LoopRotation.cpp - Loop Rotation Pass ------------------------------===//
+//
+// 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 file implements Loop Rotation Pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LoopRotation.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/MemorySSA.h"
+#include "llvm/Analysis/MemorySSAUpdater.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/LoopPassManager.h"
+#include "llvm/Transforms/Utils/LoopRotationUtils.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "loop-rotate"
+
+static cl::opt<unsigned> DefaultRotationThreshold(
+    "rotation-max-header-size", cl::init(16), cl::Hidden,
+    cl::desc("The default maximum header size for automatic loop rotation"));
+
+LoopRotatePass::LoopRotatePass(bool EnableHeaderDuplication)
+    : EnableHeaderDuplication(EnableHeaderDuplication) {}
+
+PreservedAnalyses LoopRotatePass::run(Loop &L, LoopAnalysisManager &AM,
+                                      LoopStandardAnalysisResults &AR,
+                                      LPMUpdater &) {
+  int Threshold = EnableHeaderDuplication ? DefaultRotationThreshold : 0;
+  const DataLayout &DL = L.getHeader()->getModule()->getDataLayout();
+  const SimplifyQuery SQ = getBestSimplifyQuery(AR, DL);
+
+  Optional<MemorySSAUpdater> MSSAU;
+  if (AR.MSSA)
+    MSSAU = MemorySSAUpdater(AR.MSSA);
+  bool Changed = LoopRotation(&L, &AR.LI, &AR.TTI, &AR.AC, &AR.DT, &AR.SE,
+                              MSSAU.hasValue() ? MSSAU.getPointer() : nullptr,
+                              SQ, false, Threshold, false);
+
+  if (!Changed)
+    return PreservedAnalyses::all();
+
+  if (AR.MSSA && VerifyMemorySSA)
+    AR.MSSA->verifyMemorySSA();
+
+  auto PA = getLoopPassPreservedAnalyses();
+  if (AR.MSSA)
+    PA.preserve<MemorySSAAnalysis>();
+  return PA;
+}
+
+namespace {
+
+class LoopRotateLegacyPass : public LoopPass {
+  unsigned MaxHeaderSize;
+
+public:
+  static char ID; // Pass ID, replacement for typeid
+  LoopRotateLegacyPass(int SpecifiedMaxHeaderSize = -1) : LoopPass(ID) {
+    initializeLoopRotateLegacyPassPass(*PassRegistry::getPassRegistry());
+    if (SpecifiedMaxHeaderSize == -1)
+      MaxHeaderSize = DefaultRotationThreshold;
+    else
+      MaxHeaderSize = unsigned(SpecifiedMaxHeaderSize);
+  }
+
+  // LCSSA form makes instruction renaming easier.
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<TargetTransformInfoWrapperPass>();
+    if (EnableMSSALoopDependency) {
+      AU.addRequired<MemorySSAWrapperPass>();
+      AU.addPreserved<MemorySSAWrapperPass>();
+    }
+    getLoopAnalysisUsage(AU);
+  }
+
+  bool runOnLoop(Loop *L, LPPassManager &LPM) override {
+    if (skipLoop(L))
+      return false;
+    Function &F = *L->getHeader()->getParent();
+
+    auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+    const auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+    auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+    auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+    auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
+    const SimplifyQuery SQ = getBestSimplifyQuery(*this, F);
+    Optional<MemorySSAUpdater> MSSAU;
+    if (EnableMSSALoopDependency) {
+      MemorySSA *MSSA = &getAnalysis<MemorySSAWrapperPass>().getMSSA();
+      MSSAU = MemorySSAUpdater(MSSA);
+    }
+    return LoopRotation(L, LI, TTI, AC, &DT, &SE,
+                        MSSAU.hasValue() ? MSSAU.getPointer() : nullptr, SQ,
+                        false, MaxHeaderSize, false);
+  }
+};
+}
+
+char LoopRotateLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(LoopRotateLegacyPass, "loop-rotate", "Rotate Loops",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(LoopPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
+INITIALIZE_PASS_END(LoopRotateLegacyPass, "loop-rotate", "Rotate Loops", false,
+                    false)
+
+Pass *llvm::createLoopRotatePass(int MaxHeaderSize) {
+  return new LoopRotateLegacyPass(MaxHeaderSize);
+}