[llvm] 6770de9 - [LoopIdiomRecognize] Teach LoopIdiomRecognize to preserve MemorySSA.

[Alina Sbirlea via llvm-commits]

Author: Alina Sbirlea
Date: 2020-01-23T11:31:12-08:00
New Revision: 6770de9b8d931001e33d2f02ab56a37c35b078e5

URL: https://github.com/llvm/llvm-project/commit/6770de9b8d931001e33d2f02ab56a37c35b078e5
DIFF: https://github.com/llvm/llvm-project/commit/6770de9b8d931001e33d2f02ab56a37c35b078e5.diff

LOG: [LoopIdiomRecognize] Teach LoopIdiomRecognize to preserve MemorySSA.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index e5188d524c61..ef953096015c 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -51,6 +51,8 @@
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/MemoryLocation.h"
+#include "llvm/Analysis/MemorySSA.h"
+#include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Analysis/ScalarEvolutionExpander.h"
@@ -123,15 +125,19 @@ class LoopIdiomRecognize {
   const DataLayout *DL;
   OptimizationRemarkEmitter &ORE;
   bool ApplyCodeSizeHeuristics;
+  std::unique_ptr<MemorySSAUpdater> MSSAU;
 
 public:
   explicit LoopIdiomRecognize(AliasAnalysis *AA, DominatorTree *DT,
                               LoopInfo *LI, ScalarEvolution *SE,
                               TargetLibraryInfo *TLI,
-                              const TargetTransformInfo *TTI,
+                              const TargetTransformInfo *TTI, MemorySSA *MSSA,
                               const DataLayout *DL,
                               OptimizationRemarkEmitter &ORE)
-      : AA(AA), DT(DT), LI(LI), SE(SE), TLI(TLI), TTI(TTI), DL(DL), ORE(ORE) {}
+      : AA(AA), DT(DT), LI(LI), SE(SE), TLI(TLI), TTI(TTI), DL(DL), ORE(ORE) {
+    if (MSSA)
+      MSSAU = std::make_unique<MemorySSAUpdater>(MSSA);
+  }
 
   bool runOnLoop(Loop *L);
 
@@ -224,13 +230,17 @@ class LoopIdiomRecognizeLegacyPass : public LoopPass {
         &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
             *L->getHeader()->getParent());
     const DataLayout *DL = &L->getHeader()->getModule()->getDataLayout();
+    auto *MSSAAnalysis = getAnalysisIfAvailable<MemorySSAWrapperPass>();
+    MemorySSA *MSSA = nullptr;
+    if (MSSAAnalysis)
+      MSSA = &MSSAAnalysis->getMSSA();
 
     // For the old PM, we can't use OptimizationRemarkEmitter as an analysis
     // pass.  Function analyses need to be preserved across loop transformations
     // but ORE cannot be preserved (see comment before the pass definition).
     OptimizationRemarkEmitter ORE(L->getHeader()->getParent());
 
-    LoopIdiomRecognize LIR(AA, DT, LI, SE, TLI, TTI, DL, ORE);
+    LoopIdiomRecognize LIR(AA, DT, LI, SE, TLI, TTI, MSSA, DL, ORE);
     return LIR.runOnLoop(L);
   }
 
@@ -239,6 +249,7 @@ class LoopIdiomRecognizeLegacyPass : public LoopPass {
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<TargetLibraryInfoWrapperPass>();
     AU.addRequired<TargetTransformInfoWrapperPass>();
+    AU.addPreserved<MemorySSAWrapperPass>();
     getLoopAnalysisUsage(AU);
   }
 };
@@ -263,12 +274,15 @@ PreservedAnalyses LoopIdiomRecognizePass::run(Loop &L, LoopAnalysisManager &AM,
         "LoopIdiomRecognizePass: OptimizationRemarkEmitterAnalysis not cached "
         "at a higher level");
 
-  LoopIdiomRecognize LIR(&AR.AA, &AR.DT, &AR.LI, &AR.SE, &AR.TLI, &AR.TTI, DL,
-                         *ORE);
+  LoopIdiomRecognize LIR(&AR.AA, &AR.DT, &AR.LI, &AR.SE, &AR.TLI, &AR.TTI,
+                         AR.MSSA, DL, *ORE);
   if (!LIR.runOnLoop(&L))
     return PreservedAnalyses::all();
 
-  return getLoopPassPreservedAnalyses();
+  auto PA = getLoopPassPreservedAnalyses();
+  if (AR.MSSA)
+    PA.preserve<MemorySSAAnalysis>();
+  return PA;
 }
 
 INITIALIZE_PASS_BEGIN(LoopIdiomRecognizeLegacyPass, "loop-idiom",
@@ -968,11 +982,17 @@ bool LoopIdiomRecognize::processLoopStridedStore(
     Value *PatternPtr = ConstantExpr::getBitCast(GV, Int8PtrTy);
     NewCall = Builder.CreateCall(MSP, {BasePtr, PatternPtr, NumBytes});
   }
+  NewCall->setDebugLoc(TheStore->getDebugLoc());
+
+  if (MSSAU) {
+    MemoryAccess *NewMemAcc = MSSAU->createMemoryAccessInBB(
+        NewCall, nullptr, NewCall->getParent(), MemorySSA::BeforeTerminator);
+    MSSAU->insertDef(cast<MemoryDef>(NewMemAcc), true);
+  }
 
   LLVM_DEBUG(dbgs() << "  Formed memset: " << *NewCall << "\n"
                     << "    from store to: " << *Ev << " at: " << *TheStore
                     << "\n");
-  NewCall->setDebugLoc(TheStore->getDebugLoc());
 
   ORE.emit([&]() {
     return OptimizationRemark(DEBUG_TYPE, "ProcessLoopStridedStore",
@@ -984,8 +1004,13 @@ bool LoopIdiomRecognize::processLoopStridedStore(
 
   // Okay, the memset has been formed.  Zap the original store and anything that
   // feeds into it.
-  for (auto *I : Stores)
+  for (auto *I : Stores) {
+    if (MSSAU)
+      MSSAU->removeMemoryAccess(I, true);
     deleteDeadInstruction(I);
+  }
+  if (MSSAU && VerifyMemorySSA)
+    MSSAU->getMemorySSA()->verifyMemorySSA();
   ++NumMemSet;
   return true;
 }
@@ -1112,6 +1137,12 @@ bool LoopIdiomRecognize::processLoopStoreOfLoopLoad(StoreInst *SI,
   }
   NewCall->setDebugLoc(SI->getDebugLoc());
 
+  if (MSSAU) {
+    MemoryAccess *NewMemAcc = MSSAU->createMemoryAccessInBB(
+        NewCall, nullptr, NewCall->getParent(), MemorySSA::BeforeTerminator);
+    MSSAU->insertDef(cast<MemoryDef>(NewMemAcc), true);
+  }
+
   LLVM_DEBUG(dbgs() << "  Formed memcpy: " << *NewCall << "\n"
                     << "    from load ptr=" << *LoadEv << " at: " << *LI << "\n"
                     << "    from store ptr=" << *StoreEv << " at: " << *SI
@@ -1127,7 +1158,11 @@ bool LoopIdiomRecognize::processLoopStoreOfLoopLoad(StoreInst *SI,
 
   // Okay, the memcpy has been formed.  Zap the original store and anything that
   // feeds into it.
+  if (MSSAU)
+    MSSAU->removeMemoryAccess(SI, true);
   deleteDeadInstruction(SI);
+  if (MSSAU && VerifyMemorySSA)
+    MSSAU->getMemorySSA()->verifyMemorySSA();
   ++NumMemCpy;
   return true;
 }