vendor/llvm/llvm-trunk-r366426

1 files changed, 69 insertions, 25 deletions

diff --git a/lib/Analysis/LoopAccessAnalysis.cpp b/lib/Analysis/LoopAccessAnalysis.cpp
index 7f3480f512ab..36bd9a8b7ea7 100644
--- a/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1,9 +1,8 @@
 //===- LoopAccessAnalysis.cpp - Loop Access Analysis Implementation --------==//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
 //
 //===----------------------------------------------------------------------===//
 //
@@ -843,7 +842,7 @@ void AccessAnalysis::processMemAccesses() {
     bool SetHasWrite = false;
 
     // Map of pointers to last access encountered.
-    typedef DenseMap<Value*, MemAccessInfo> UnderlyingObjToAccessMap;
+    typedef DenseMap<const Value*, MemAccessInfo> UnderlyingObjToAccessMap;
     UnderlyingObjToAccessMap ObjToLastAccess;
 
     // Set of access to check after all writes have been processed.
@@ -904,13 +903,13 @@ void AccessAnalysis::processMemAccesses() {
 
           // Create sets of pointers connected by a shared alias set and
           // underlying object.
-          typedef SmallVector<Value *, 16> ValueVector;
+          typedef SmallVector<const Value *, 16> ValueVector;
           ValueVector TempObjects;
 
           GetUnderlyingObjects(Ptr, TempObjects, DL, LI);
           LLVM_DEBUG(dbgs()
                      << "Underlying objects for pointer " << *Ptr << "\n");
-          for (Value *UnderlyingObj : TempObjects) {
+          for (const Value *UnderlyingObj : TempObjects) {
             // nullptr never alias, don't join sets for pointer that have "null"
             // in their UnderlyingObjects list.
             if (isa<ConstantPointerNull>(UnderlyingObj) &&
@@ -1014,7 +1013,7 @@ int64_t llvm::getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr,
     return 0;
   }
 
-  // The accesss function must stride over the innermost loop.
+  // The access function must stride over the innermost loop.
   if (Lp != AR->getLoop()) {
     LLVM_DEBUG(dbgs() << "LAA: Bad stride - Not striding over innermost loop "
                       << *Ptr << " SCEV: " << *AR << "\n");
@@ -1086,7 +1085,7 @@ int64_t llvm::getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr,
     if (Assume) {
       // We can avoid this case by adding a run-time check.
       LLVM_DEBUG(dbgs() << "LAA: Non unit strided pointer which is not either "
-                        << "inbouds or in address space 0 may wrap:\n"
+                        << "inbounds or in address space 0 may wrap:\n"
                         << "LAA:   Pointer: " << *Ptr << "\n"
                         << "LAA:   SCEV: " << *AR << "\n"
                         << "LAA:   Added an overflow assumption\n");
@@ -1145,10 +1144,9 @@ bool llvm::sortPtrAccesses(ArrayRef<Value *> VL, const DataLayout &DL,
   std::iota(SortedIndices.begin(), SortedIndices.end(), 0);
 
   // Sort the memory accesses and keep the order of their uses in UseOrder.
-  std::stable_sort(SortedIndices.begin(), SortedIndices.end(),
-                   [&OffValPairs](unsigned Left, unsigned Right) {
-                     return OffValPairs[Left].first < OffValPairs[Right].first;
-                   });
+  llvm::stable_sort(SortedIndices, [&](unsigned Left, unsigned Right) {
+    return OffValPairs[Left].first < OffValPairs[Right].first;
+  });
 
   // Check if the order is consecutive already.
   if (llvm::all_of(SortedIndices, [&SortedIndices](const unsigned I) {
@@ -1346,7 +1344,7 @@ static bool isSafeDependenceDistance(const DataLayout &DL, ScalarEvolution &SE,
   // where Step is the absolute stride of the memory accesses in bytes,
   // then there is no dependence.
   //
-  // Ratioanle:
+  // Rationale:
   // We basically want to check if the absolute distance (|Dist/Step|)
   // is >= the loop iteration count (or > BackedgeTakenCount).
   // This is equivalent to the Strong SIV Test (Practical Dependence Testing,
@@ -1369,7 +1367,7 @@ static bool isSafeDependenceDistance(const DataLayout &DL, ScalarEvolution &SE,
 
   // The dependence distance can be positive/negative, so we sign extend Dist;
   // The multiplication of the absolute stride in bytes and the
-  // backdgeTakenCount is non-negative, so we zero extend Product.
+  // backedgeTakenCount is non-negative, so we zero extend Product.
   if (DistTypeSize > ProductTypeSize)
     CastedProduct = SE.getZeroExtendExpr(Product, Dist.getType());
   else
@@ -1780,6 +1778,11 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
   unsigned NumReads = 0;
   unsigned NumReadWrites = 0;
 
+  bool HasComplexMemInst = false;
+
+  // A runtime check is only legal to insert if there are no convergent calls.
+  HasConvergentOp = false;
+
   PtrRtChecking->Pointers.clear();
   PtrRtChecking->Need = false;
 
@@ -1787,8 +1790,25 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
 
   // For each block.
   for (BasicBlock *BB : TheLoop->blocks()) {
-    // Scan the BB and collect legal loads and stores.
+    // Scan the BB and collect legal loads and stores. Also detect any
+    // convergent instructions.
     for (Instruction &I : *BB) {
+      if (auto *Call = dyn_cast<CallBase>(&I)) {
+        if (Call->isConvergent())
+          HasConvergentOp = true;
+      }
+
+      // With both a non-vectorizable memory instruction and a convergent
+      // operation, found in this loop, no reason to continue the search.
+      if (HasComplexMemInst && HasConvergentOp) {
+        CanVecMem = false;
+        return;
+      }
+
+      // Avoid hitting recordAnalysis multiple times.
+      if (HasComplexMemInst)
+        continue;
+
       // If this is a load, save it. If this instruction can read from memory
       // but is not a load, then we quit. Notice that we don't handle function
       // calls that read or write.
@@ -1807,12 +1827,18 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
           continue;
 
         auto *Ld = dyn_cast<LoadInst>(&I);
-        if (!Ld || (!Ld->isSimple() && !IsAnnotatedParallel)) {
+        if (!Ld) {
+          recordAnalysis("CantVectorizeInstruction", Ld)
+            << "instruction cannot be vectorized";
+          HasComplexMemInst = true;
+          continue;
+        }
+        if (!Ld->isSimple() && !IsAnnotatedParallel) {
           recordAnalysis("NonSimpleLoad", Ld)
               << "read with atomic ordering or volatile read";
           LLVM_DEBUG(dbgs() << "LAA: Found a non-simple load.\n");
-          CanVecMem = false;
-          return;
+          HasComplexMemInst = true;
+          continue;
         }
         NumLoads++;
         Loads.push_back(Ld);
@@ -1828,15 +1854,15 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
         if (!St) {
           recordAnalysis("CantVectorizeInstruction", St)
               << "instruction cannot be vectorized";
-          CanVecMem = false;
-          return;
+          HasComplexMemInst = true;
+          continue;
         }
         if (!St->isSimple() && !IsAnnotatedParallel) {
           recordAnalysis("NonSimpleStore", St)
               << "write with atomic ordering or volatile write";
           LLVM_DEBUG(dbgs() << "LAA: Found a non-simple store.\n");
-          CanVecMem = false;
-          return;
+          HasComplexMemInst = true;
+          continue;
         }
         NumStores++;
         Stores.push_back(St);
@@ -1847,6 +1873,11 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
     } // Next instr.
   } // Next block.
 
+  if (HasComplexMemInst) {
+    CanVecMem = false;
+    return;
+  }
+
   // Now we have two lists that hold the loads and the stores.
   // Next, we find the pointers that they use.
 
@@ -1964,7 +1995,7 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
   }
 
   LLVM_DEBUG(
-      dbgs() << "LAA: We can perform a memory runtime check if needed.\n");
+    dbgs() << "LAA: May be able to perform a memory runtime check if needed.\n");
 
   CanVecMem = true;
   if (Accesses.isDependencyCheckNeeded()) {
@@ -1999,6 +2030,15 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
     }
   }
 
+  if (HasConvergentOp) {
+    recordAnalysis("CantInsertRuntimeCheckWithConvergent")
+      << "cannot add control dependency to convergent operation";
+    LLVM_DEBUG(dbgs() << "LAA: We can't vectorize because a runtime check "
+                         "would be needed with a convergent operation\n");
+    CanVecMem = false;
+    return;
+  }
+
   if (CanVecMem)
     LLVM_DEBUG(
         dbgs() << "LAA: No unsafe dependent memory operations in loop.  We"
@@ -2252,7 +2292,7 @@ void LoopAccessInfo::collectStridedAccess(Value *MemAccess) {
 
   // Match the types so we can compare the stride and the BETakenCount.
   // The Stride can be positive/negative, so we sign extend Stride;
-  // The backdgeTakenCount is non-negative, so we zero extend BETakenCount.
+  // The backedgeTakenCount is non-negative, so we zero extend BETakenCount.
   const DataLayout &DL = TheLoop->getHeader()->getModule()->getDataLayout();
   uint64_t StrideTypeSize = DL.getTypeAllocSize(StrideExpr->getType());
   uint64_t BETypeSize = DL.getTypeAllocSize(BETakenCount->getType());
@@ -2287,6 +2327,7 @@ LoopAccessInfo::LoopAccessInfo(Loop *L, ScalarEvolution *SE,
       PtrRtChecking(llvm::make_unique<RuntimePointerChecking>(SE)),
       DepChecker(llvm::make_unique<MemoryDepChecker>(*PSE, L)), TheLoop(L),
       NumLoads(0), NumStores(0), MaxSafeDepDistBytes(-1), CanVecMem(false),
+      HasConvergentOp(false),
       HasDependenceInvolvingLoopInvariantAddress(false) {
   if (canAnalyzeLoop())
     analyzeLoop(AA, LI, TLI, DT);
@@ -2303,6 +2344,9 @@ void LoopAccessInfo::print(raw_ostream &OS, unsigned Depth) const {
     OS << "\n";
   }
 
+  if (HasConvergentOp)
+    OS.indent(Depth) << "Has convergent operation in loop\n";
+
   if (Report)
     OS.indent(Depth) << "Report: " << Report->getMsg() << "\n";