[DAGCombine] NFC. MatchLoadCombine extract MemoryByteOffset lambda he…

…lper

This refactoring will simplify the upcoming change to fix the bug in folding patterns with non-zero offsets on BE targets.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296332 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -4516,16 +4516,25 @@ SDValue DAGCombiner::MatchLoadCombine(SDNode *N) {
   std::function<unsigned(unsigned, unsigned)> BigEndianByteAt = [](
     unsigned BW, unsigned i) { return BW - i - 1; };
 
+  bool IsBigEndianTarget = DAG.getDataLayout().isBigEndian();
+  auto MemoryByteOffset = [&] (ByteProvider P) {
+    assert(P.isMemory() && "Must be a memory byte provider");
+    unsigned LoadBitWidth = P.Load->getMemoryVT().getSizeInBits();
+    assert(LoadBitWidth % 8 == 0 &&
+           "can only analyze providers for individual bytes not bit");
+    unsigned LoadByteWidth = LoadBitWidth / 8;
+    return IsBigEndianTarget
+            ? BigEndianByteAt(LoadByteWidth, P.ByteOffset)
+            : LittleEndianByteAt(LoadByteWidth, P.ByteOffset);
+  };
+
   Optional<BaseIndexOffset> Base;
   SDValue Chain;
 
   SmallSet<LoadSDNode *, 8> Loads;
   Optional<ByteProvider> FirstByteProvider;
   int64_t FirstOffset = INT64_MAX;
 
-  bool IsBigEndianTarget = DAG.getDataLayout().isBigEndian();
-  auto ByteAt = IsBigEndianTarget ? BigEndianByteAt : LittleEndianByteAt;
-
   // Check if all the bytes of the OR we are looking at are loaded from the same
   // base address. Collect bytes offsets from Base address in ByteOffsets.
   SmallVector<int64_t, 4> ByteOffsets(ByteWidth);
@@ -4555,12 +4564,7 @@ SDValue DAGCombiner::MatchLoadCombine(SDNode *N) {
       return SDValue();
 
     // Calculate the offset of the current byte from the base address
-    unsigned LoadBitWidth = L->getMemoryVT().getSizeInBits();
-    assert(LoadBitWidth % 8 == 0 &&
-           "can only analyze providers for individual bytes not bit");
-    unsigned LoadByteWidth = LoadBitWidth / 8;
-    int64_t MemoryByteOffset = ByteAt(LoadByteWidth, P->ByteOffset);
-    int64_t ByteOffsetFromBase = Ptr.Offset + MemoryByteOffset;
+    int64_t ByteOffsetFromBase = Ptr.Offset + MemoryByteOffset(*P);
     ByteOffsets[i] = ByteOffsetFromBase;
 
     // Remember the first byte load