[New PM][IRCE] port of Inductive Range Check Elimination pass to the new pass manager

There are two nontrivial details here:
* Loop structure update interface is quite different with new pass manager,
  so the code to add new loops was factored out

* BranchProbabilityInfo is not a loop analysis, so it can not be just getResult'ed from
  within the loop pass. It cant even be queried through getCachedResult as LoopCanonicalization
  sequence (e.g. LoopSimplify) might invalidate BPI results.

  Complete solution for BPI will likely take some time to discuss and figure out,
  so for now this was partially solved by making BPI optional in IRCE
  (skipping a couple of profitability checks if it is absent).

Most of the IRCE tests got their corresponding new-pass-manager variant enabled.
Only two of them depend on BPI, both marked with TODO, to be turned on when BPI
starts being available for loop passes.

Reviewers: chandlerc, mkazantsev, sanjoy, asbirlea
Reviewed By: mkazantsev
Differential Revision: https://reviews.llvm.org/D43795

llvm-svn: 327619

1 files changed, 88 insertions, 39 deletions

diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
index 8653bede620..9d965d8e131 100644
--- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
@@ -43,6 +43,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/InductiveRangeCheckElimination.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/None.h"
@@ -52,6 +53,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
+#include "llvm/Analysis/LoopAnalysisManager.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/ScalarEvolution.h"
@@ -235,17 +237,31 @@ public:
   /// checks, and hence don't end up in \p Checks.
   static void
   extractRangeChecksFromBranch(BranchInst *BI, Loop *L, ScalarEvolution &SE,
-                               BranchProbabilityInfo &BPI,
+                               BranchProbabilityInfo *BPI,
                                SmallVectorImpl<InductiveRangeCheck> &Checks);
 };
 
-class InductiveRangeCheckElimination : public LoopPass {
+class InductiveRangeCheckElimination {
+  ScalarEvolution &SE;
+  BranchProbabilityInfo *BPI;
+  DominatorTree &DT;
+  LoopInfo &LI;
+
+public:
+  InductiveRangeCheckElimination(ScalarEvolution &SE,
+                                 BranchProbabilityInfo *BPI, DominatorTree &DT,
+                                 LoopInfo &LI)
+      : SE(SE), BPI(BPI), DT(DT), LI(LI) {}
+
+  bool run(Loop *L, function_ref<void(Loop *, bool)> LPMAddNewLoop);
+};
+
+class IRCELegacyPass : public LoopPass {
 public:
   static char ID;
 
-  InductiveRangeCheckElimination() : LoopPass(ID) {
-    initializeInductiveRangeCheckEliminationPass(
-        *PassRegistry::getPassRegistry());
+  IRCELegacyPass() : LoopPass(ID) {
+    initializeIRCELegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
@@ -258,14 +274,14 @@ public:
 
 } // end anonymous namespace
 
-char InductiveRangeCheckElimination::ID = 0;
+char IRCELegacyPass::ID = 0;
 
-INITIALIZE_PASS_BEGIN(InductiveRangeCheckElimination, "irce",
+INITIALIZE_PASS_BEGIN(IRCELegacyPass, "irce",
                       "Inductive range check elimination", false, false)
 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopPass)
-INITIALIZE_PASS_END(InductiveRangeCheckElimination, "irce",
-                    "Inductive range check elimination", false, false)
+INITIALIZE_PASS_END(IRCELegacyPass, "irce", "Inductive range check elimination",
+                    false, false)
 
 StringRef InductiveRangeCheck::rangeCheckKindToStr(
     InductiveRangeCheck::RangeCheckKind RCK) {
@@ -417,15 +433,15 @@ void InductiveRangeCheck::extractRangeChecksFromCond(
 }
 
 void InductiveRangeCheck::extractRangeChecksFromBranch(
-    BranchInst *BI, Loop *L, ScalarEvolution &SE, BranchProbabilityInfo &BPI,
+    BranchInst *BI, Loop *L, ScalarEvolution &SE, BranchProbabilityInfo *BPI,
     SmallVectorImpl<InductiveRangeCheck> &Checks) {
   if (BI->isUnconditional() || BI->getParent() == L->getLoopLatch())
     return;
 
   BranchProbability LikelyTaken(15, 16);
 
-  if (!SkipProfitabilityChecks &&
-      BPI.getEdgeProbability(BI->getParent(), (unsigned)0) < LikelyTaken)
+  if (!SkipProfitabilityChecks && BPI &&
+      BPI->getEdgeProbability(BI->getParent(), (unsigned)0) < LikelyTaken)
     return;
 
   SmallPtrSet<Value *, 8> Visited;
@@ -516,9 +532,8 @@ struct LoopStructure {
   }
 
   static Optional<LoopStructure> parseLoopStructure(ScalarEvolution &,
-                                                    BranchProbabilityInfo &BPI,
-                                                    Loop &,
-                                                    const char *&);
+                                                    BranchProbabilityInfo *BPI,
+                                                    Loop &, const char *&);
 };
 
 /// This class is used to constrain loops to run within a given iteration space.
@@ -585,7 +600,7 @@ class LoopConstrainer {
   // Create the appropriate loop structure needed to describe a cloned copy of
   // `Original`.  The clone is described by `VM`.
   Loop *createClonedLoopStructure(Loop *Original, Loop *Parent,
-                                  ValueToValueMapTy &VM);
+                                  ValueToValueMapTy &VM, bool IsSubloop);
 
   // Rewrite the iteration space of the loop denoted by (LS, Preheader). The
   // iteration space of the rewritten loop ends at ExitLoopAt.  The start of the
@@ -637,8 +652,8 @@ class LoopConstrainer {
   LLVMContext &Ctx;
   ScalarEvolution &SE;
   DominatorTree &DT;
-  LPPassManager &LPM;
   LoopInfo &LI;
+  function_ref<void(Loop *, bool)> LPMAddNewLoop;
 
   // Information about the original loop we started out with.
   Loop &OriginalLoop;
@@ -658,12 +673,13 @@ class LoopConstrainer {
   LoopStructure MainLoopStructure;
 
 public:
-  LoopConstrainer(Loop &L, LoopInfo &LI, LPPassManager &LPM,
+  LoopConstrainer(Loop &L, LoopInfo &LI,
+                  function_ref<void(Loop *, bool)> LPMAddNewLoop,
                   const LoopStructure &LS, ScalarEvolution &SE,
                   DominatorTree &DT, InductiveRangeCheck::Range R)
       : F(*L.getHeader()->getParent()), Ctx(L.getHeader()->getContext()),
-        SE(SE), DT(DT), LPM(LPM), LI(LI), OriginalLoop(L), Range(R),
-        MainLoopStructure(LS) {}
+        SE(SE), DT(DT), LI(LI), LPMAddNewLoop(LPMAddNewLoop), OriginalLoop(L),
+        Range(R), MainLoopStructure(LS) {}
 
   // Entry point for the algorithm.  Returns true on success.
   bool run();
@@ -726,8 +742,8 @@ static bool SumCanReachMin(ScalarEvolution &SE, const SCEV *S1, const SCEV *S2,
 
 Optional<LoopStructure>
 LoopStructure::parseLoopStructure(ScalarEvolution &SE,
-                                  BranchProbabilityInfo &BPI,
-                                  Loop &L, const char *&FailureReason) {
+                                  BranchProbabilityInfo *BPI, Loop &L,
+                                  const char *&FailureReason) {
   if (!L.isLoopSimplifyForm()) {
     FailureReason = "loop not in LoopSimplify form";
     return None;
@@ -762,7 +778,8 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE,
   unsigned LatchBrExitIdx = LatchBr->getSuccessor(0) == Header ? 1 : 0;
 
   BranchProbability ExitProbability =
-    BPI.getEdgeProbability(LatchBr->getParent(), LatchBrExitIdx);
+      BPI ? BPI->getEdgeProbability(LatchBr->getParent(), LatchBrExitIdx)
+          : BranchProbability::getZero();
 
   if (!SkipProfitabilityChecks &&
       ExitProbability > BranchProbability(1, MaxExitProbReciprocal)) {
@@ -1396,13 +1413,14 @@ void LoopConstrainer::addToParentLoopIfNeeded(ArrayRef<BasicBlock *> BBs) {
 }
 
 Loop *LoopConstrainer::createClonedLoopStructure(Loop *Original, Loop *Parent,
-                                                 ValueToValueMapTy &VM) {
+                                                 ValueToValueMapTy &VM,
+                                                 bool IsSubloop) {
   Loop &New = *LI.AllocateLoop();
   if (Parent)
     Parent->addChildLoop(&New);
   else
     LI.addTopLevelLoop(&New);
-  LPM.addLoop(New);
+  LPMAddNewLoop(&New, IsSubloop);
 
   // Add all of the blocks in Original to the new loop.
   for (auto *BB : Original->blocks())
@@ -1411,7 +1429,7 @@ Loop *LoopConstrainer::createClonedLoopStructure(Loop *Original, Loop *Parent,
 
   // Add all of the subloops to the new loop.
   for (Loop *SubLoop : *Original)
-    createClonedLoopStructure(SubLoop, &New, VM);
+    createClonedLoopStructure(SubLoop, &New, VM, /* IsSubloop */ true);
 
   return &New;
 }
@@ -1561,13 +1579,15 @@ bool LoopConstrainer::run() {
   // LI when LoopSimplifyForm is generated.
   Loop *PreL = nullptr, *PostL = nullptr;
   if (!PreLoop.Blocks.empty()) {
-    PreL = createClonedLoopStructure(
-        &OriginalLoop, OriginalLoop.getParentLoop(), PreLoop.Map);
+    PreL = createClonedLoopStructure(&OriginalLoop,
+                                     OriginalLoop.getParentLoop(), PreLoop.Map,
+                                     /* IsSubLoop */ false);
   }
 
   if (!PostLoop.Blocks.empty()) {
-    PostL = createClonedLoopStructure(
-        &OriginalLoop, OriginalLoop.getParentLoop(), PostLoop.Map);
+    PostL =
+        createClonedLoopStructure(&OriginalLoop, OriginalLoop.getParentLoop(),
+                                  PostLoop.Map, /* IsSubLoop */ false);
   }
 
   // This function canonicalizes the loop into Loop-Simplify and LCSSA forms.
@@ -1738,12 +1758,45 @@ IntersectUnsignedRange(ScalarEvolution &SE,
   return Ret;
 }
 
-bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
+PreservedAnalyses IRCEPass::run(Loop &L, LoopAnalysisManager &AM,
+                                LoopStandardAnalysisResults &AR,
+                                LPMUpdater &U) {
+  Function *F = L.getHeader()->getParent();
+  const auto &FAM =
+      AM.getResult<FunctionAnalysisManagerLoopProxy>(L, AR).getManager();
+  auto *BPI = FAM.getCachedResult<BranchProbabilityAnalysis>(*F);
+  InductiveRangeCheckElimination IRCE(AR.SE, BPI, AR.DT, AR.LI);
+  auto LPMAddNewLoop = [&U](Loop *NL, bool IsSubloop) {
+    if (!IsSubloop)
+      U.addSiblingLoops(NL);
+  };
+  bool Changed = IRCE.run(&L, LPMAddNewLoop);
+  if (!Changed)
+    return PreservedAnalyses::all();
+
+  return getLoopPassPreservedAnalyses();
+}
+
+bool IRCELegacyPass::runOnLoop(Loop *L, LPPassManager &LPM) {
   if (skipLoop(L))
     return false;
 
+  ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
+  BranchProbabilityInfo &BPI =
+      getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
+  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+  InductiveRangeCheckElimination IRCE(SE, &BPI, DT, LI);
+  auto LPMAddNewLoop = [&LPM](Loop *NL, bool /* IsSubLoop */) {
+    LPM.addLoop(*NL);
+  };
+  return IRCE.run(L, LPMAddNewLoop);
+}
+
+bool InductiveRangeCheckElimination::run(
+    Loop *L, function_ref<void(Loop *, bool)> LPMAddNewLoop) {
   if (L->getBlocks().size() >= LoopSizeCutoff) {
-    DEBUG(dbgs() << "irce: giving up constraining loop, too large\n";);
+    DEBUG(dbgs() << "irce: giving up constraining loop, too large\n");
     return false;
   }
 
@@ -1755,9 +1808,6 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
 
   LLVMContext &Context = Preheader->getContext();
   SmallVector<InductiveRangeCheck, 16> RangeChecks;
-  ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
-  BranchProbabilityInfo &BPI =
-      getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
 
   for (auto BBI : L->getBlocks())
     if (BranchInst *TBI = dyn_cast<BranchInst>(BBI->getTerminator()))
@@ -1823,9 +1873,8 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
   if (!SafeIterRange.hasValue())
     return false;
 
-  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-  LoopConstrainer LC(*L, getAnalysis<LoopInfoWrapperPass>().getLoopInfo(), LPM,
-                     LS, SE, DT, SafeIterRange.getValue());
+  LoopConstrainer LC(*L, LI, LPMAddNewLoop, LS, SE, DT,
+                     SafeIterRange.getValue());
   bool Changed = LC.run();
 
   if (Changed) {
@@ -1855,5 +1904,5 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
 }
 
 Pass *llvm::createInductiveRangeCheckEliminationPass() {
-  return new InductiveRangeCheckElimination;
+  return new IRCELegacyPass();
 }