[DAG] Integrate findBaseOffset address analyses to BaseIndexOffset. NFCI.

BaseIndexOffset supercedes findBaseOffset analysis save only Constant
Pool addresses. Migrate analysis to BaseIndexOffset.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321364 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -17405,43 +17405,6 @@ SDValue DAGCombiner::buildSqrtEstimate(SDValue Op, SDNodeFlags Flags) {
   return buildSqrtEstimateImpl(Op, Flags, false);
 }
 
-/// Return true if base is a frame index, which is known not to alias with
-/// anything but itself.  Provides base object and offset as results.
-static bool findBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset,
-                           const GlobalValue *&GV, const void *&CV) {
-  // Assume it is a primitive operation.
-  Base = Ptr; Offset = 0; GV = nullptr; CV = nullptr;
-
-  // If it's an adding a simple constant then integrate the offset.
-  if (Base.getOpcode() == ISD::ADD) {
-    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Base.getOperand(1))) {
-      Base = Base.getOperand(0);
-      Offset += C->getSExtValue();
-    }
-  }
-
-  // Return the underlying GlobalValue, and update the Offset.  Return false
-  // for GlobalAddressSDNode since the same GlobalAddress may be represented
-  // by multiple nodes with different offsets.
-  if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Base)) {
-    GV = G->getGlobal();
-    Offset += G->getOffset();
-    return false;
-  }
-
-  // Return the underlying Constant value, and update the Offset.  Return false
-  // for ConstantSDNodes since the same constant pool entry may be represented
-  // by multiple nodes with different offsets.
-  if (ConstantPoolSDNode *C = dyn_cast<ConstantPoolSDNode>(Base)) {
-    CV = C->isMachineConstantPoolEntry() ? (const void *)C->getMachineCPVal()
-                                         : (const void *)C->getConstVal();
-    Offset += C->getOffset();
-    return false;
-  }
-  // If it's any of the following then it can't alias with anything but itself.
-  return isa<FrameIndexSDNode>(Base);
-}
-
 /// Return true if there is any possibility that the two addresses overlap.
 bool DAGCombiner::isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) const {
   // If they are the same then they must be aliases.
@@ -17483,39 +17446,16 @@ bool DAGCombiner::isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) const {
         return false;
     }
 
-  // FIXME: findBaseOffset and ConstantValue/GlobalValue/FrameIndex analysis
-  // modified to use BaseIndexOffset.
-
-  // Gather base node and offset information.
-  SDValue Base0, Base1;
-  int64_t Offset0, Offset1;
-  const GlobalValue *GV0, *GV1;
-  const void *CV0, *CV1;
-  bool IsFrameIndex0 = findBaseOffset(Op0->getBasePtr(),
-                                      Base0, Offset0, GV0, CV0);
-  bool IsFrameIndex1 = findBaseOffset(Op1->getBasePtr(),
-                                      Base1, Offset1, GV1, CV1);
-
-  // If they have the same base address, then check to see if they overlap.
-  if (Base0 == Base1 || (GV0 && (GV0 == GV1)) || (CV0 && (CV0 == CV1)))
-    return !((Offset0 + NumBytes0) <= Offset1 ||
-             (Offset1 + NumBytes1) <= Offset0);
-
-  // It is possible for different frame indices to alias each other, mostly
-  // when tail call optimization reuses return address slots for arguments.
-  // To catch this case, look up the actual index of frame indices to compute
-  // the real alias relationship.
-  if (IsFrameIndex0 && IsFrameIndex1) {
-    MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
-    Offset0 += MFI.getObjectOffset(cast<FrameIndexSDNode>(Base0)->getIndex());
-    Offset1 += MFI.getObjectOffset(cast<FrameIndexSDNode>(Base1)->getIndex());
-    return !((Offset0 + NumBytes0) <= Offset1 ||
-             (Offset1 + NumBytes1) <= Offset0);
-  }
-
-  // Otherwise, if we know what the bases are, and they aren't identical, then
-  // we know they cannot alias.
-  if ((IsFrameIndex0 || CV0 || GV0) && (IsFrameIndex1 || CV1 || GV1))
+  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());
+
+  // Matched types are already handled above. So if this is true they
+  // cannot alias.
+  if ((IsFI0 || IsGV0 || IsCV0) && (IsFI1 || IsGV1 || IsCV1))
     return false;
 
   // If we know required SrcValue1 and SrcValue2 have relatively large alignment

lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp

@@ -37,6 +37,23 @@ bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
           return true;
         }
 
+    // Match Constants
+    if (auto *A = dyn_cast<ConstantPoolSDNode>(Base))
+      if (auto *B = dyn_cast<ConstantPoolSDNode>(Other.Base)) {
+        bool IsMatch =
+            A->isMachineConstantPoolEntry() == B->isMachineConstantPoolEntry();
+        if (IsMatch) {
+          if (A->isMachineConstantPoolEntry())
+            IsMatch = A->getMachineCPVal() == B->getMachineCPVal();
+          else
+            IsMatch = A->getConstVal() == B->getConstVal();
+        }
+        if (IsMatch) {
+          Off += B->getOffset() - A->getOffset();
+          return true;
+        }
+      }
+
     const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
 
     // Match non-equal FrameIndexes - If both frame indices are fixed