1 files changed, 128 insertions, 11 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
index 488bac1a9a80..9592bc30a4e1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -1,9 +1,8 @@
 //==- llvm/CodeGen/SelectionDAGAddressAnalysis.cpp - DAG Address Analysis --==//
 //
-//                     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
 //
 //===----------------------------------------------------------------------===//
 
@@ -25,8 +24,10 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
   // Conservatively fail if we a match failed..
   if (!Base.getNode() || !Other.Base.getNode())
     return false;
+  if (!hasValidOffset() || !Other.hasValidOffset())
+    return false;
   // Initial Offset difference.
-  Off = Other.Offset - Offset;
+  Off = *Other.Offset - *Offset;
 
   if ((Other.Index == Index) && (Other.IsIndexSignExt == IsIndexSignExt)) {
     // Trivial match.
@@ -60,24 +61,110 @@ bool BaseIndexOffset::equalBaseIndex(const BaseIndexOffset &Other,
 
     const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
 
-    // Match non-equal FrameIndexes - If both frame indices are fixed
-    // we know their relative offsets and can compare them. Otherwise
-    // we must be conservative.
+    // Match FrameIndexes.
     if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
-      if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base))
+      if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base)) {
+        // Equal FrameIndexes - offsets are directly comparable.
+        if (A->getIndex() == B->getIndex())
+          return true;
+        // Non-equal FrameIndexes - If both frame indices are fixed
+        // we know their relative offsets and can compare them. Otherwise
+        // we must be conservative.
         if (MFI.isFixedObjectIndex(A->getIndex()) &&
             MFI.isFixedObjectIndex(B->getIndex())) {
           Off += MFI.getObjectOffset(B->getIndex()) -
                  MFI.getObjectOffset(A->getIndex());
           return true;
         }
+      }
   }
   return false;
 }
 
+bool BaseIndexOffset::computeAliasing(const SDNode *Op0,
+                                      const Optional<int64_t> NumBytes0,
+                                      const SDNode *Op1,
+                                      const Optional<int64_t> NumBytes1,
+                                      const SelectionDAG &DAG, bool &IsAlias) {
+
+  BaseIndexOffset BasePtr0 = match(Op0, DAG);
+  BaseIndexOffset BasePtr1 = match(Op1, DAG);
+
+  if (!(BasePtr0.getBase().getNode() && BasePtr1.getBase().getNode()))
+    return false;
+  int64_t PtrDiff;
+  if (NumBytes0.hasValue() && NumBytes1.hasValue() &&
+      BasePtr0.equalBaseIndex(BasePtr1, DAG, PtrDiff)) {
+    // BasePtr1 is PtrDiff away from BasePtr0. They alias if none of the
+    // following situations arise:
+    IsAlias = !(
+        // [----BasePtr0----]
+        //                         [---BasePtr1--]
+        // ========PtrDiff========>
+        (*NumBytes0 <= PtrDiff) ||
+        //                     [----BasePtr0----]
+        // [---BasePtr1--]
+        // =====(-PtrDiff)====>
+        (PtrDiff + *NumBytes1 <= 0)); // i.e. *NumBytes1 < -PtrDiff.
+    return true;
+  }
+  // If both BasePtr0 and BasePtr1 are FrameIndexes, we will not be
+  // able to calculate their relative offset if at least one arises
+  // from an alloca. However, these allocas cannot overlap and we
+  // can infer there is no alias.
+  if (auto *A = dyn_cast<FrameIndexSDNode>(BasePtr0.getBase()))
+    if (auto *B = dyn_cast<FrameIndexSDNode>(BasePtr1.getBase())) {
+      MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
+      // If the base are the same frame index but the we couldn't find a
+      // constant offset, (indices are different) be conservative.
+      if (A != B && (!MFI.isFixedObjectIndex(A->getIndex()) ||
+                     !MFI.isFixedObjectIndex(B->getIndex()))) {
+        IsAlias = false;
+        return true;
+      }
+    }
+
+  bool IsFI0 = isa<FrameIndexSDNode>(BasePtr0.getBase());
+  bool IsFI1 = isa<FrameIndexSDNode>(BasePtr1.getBase());
+  bool IsGV0 = isa<GlobalAddressSDNode>(BasePtr0.getBase());
+  bool IsGV1 = isa<GlobalAddressSDNode>(BasePtr1.getBase());
+  bool IsCV0 = isa<ConstantPoolSDNode>(BasePtr0.getBase());
+  bool IsCV1 = isa<ConstantPoolSDNode>(BasePtr1.getBase());
+
+  // If of mismatched base types or checkable indices we can check
+  // they do not alias.
+  if ((BasePtr0.getIndex() == BasePtr1.getIndex() || (IsFI0 != IsFI1) ||
+       (IsGV0 != IsGV1) || (IsCV0 != IsCV1)) &&
+      (IsFI0 || IsGV0 || IsCV0) && (IsFI1 || IsGV1 || IsCV1)) {
+    IsAlias = false;
+    return true;
+  }
+  return false; // Cannot determine whether the pointers alias.
+}
+
+bool BaseIndexOffset::contains(const SelectionDAG &DAG, int64_t BitSize,
+                               const BaseIndexOffset &Other,
+                               int64_t OtherBitSize, int64_t &BitOffset) const {
+  int64_t Offset;
+  if (!equalBaseIndex(Other, DAG, Offset))
+    return false;
+  if (Offset >= 0) {
+    // Other is after *this:
+    // [-------*this---------]
+    //            [---Other--]
+    // ==Offset==>
+    BitOffset = 8 * Offset;
+    return BitOffset + OtherBitSize <= BitSize;
+  }
+  // Other starts strictly before *this, it cannot be fully contained.
+  //    [-------*this---------]
+  // [--Other--]
+  return false;
+}
+
 /// Parses tree in Ptr for base, index, offset addresses.
-BaseIndexOffset BaseIndexOffset::match(const LSBaseSDNode *N,
-                                       const SelectionDAG &DAG) {
+static BaseIndexOffset matchLSNode(const LSBaseSDNode *N,
+                                   const SelectionDAG &DAG) {
   SDValue Ptr = N->getBasePtr();
 
   // (((B + I*M) + c)) + c ...
@@ -178,3 +265,33 @@ BaseIndexOffset BaseIndexOffset::match(const LSBaseSDNode *N,
   }
   return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
 }
+
+BaseIndexOffset BaseIndexOffset::match(const SDNode *N,
+                                       const SelectionDAG &DAG) {
+  if (const auto *LS0 = dyn_cast<LSBaseSDNode>(N))
+    return matchLSNode(LS0, DAG);
+  if (const auto *LN = dyn_cast<LifetimeSDNode>(N)) {
+    if (LN->hasOffset())
+      return BaseIndexOffset(LN->getOperand(1), SDValue(), LN->getOffset(),
+                             false);
+    return BaseIndexOffset(LN->getOperand(1), SDValue(), false);
+  }
+  return BaseIndexOffset();
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+
+LLVM_DUMP_METHOD void BaseIndexOffset::dump() const {
+  print(dbgs());
+}
+
+void BaseIndexOffset::print(raw_ostream& OS) const {
+  OS << "BaseIndexOffset base=[";
+  Base->print(OS);
+  OS << "] index=[";
+  if (Index)
+    Index->print(OS);
+  OS << "] offset=" << Offset;
+}
+
+#endif