[DAGCombiner] revert r295336

r295336 causes a bootstrapped clang to fail for many compilations on
powerpc BE.  See 
http://lab.llvm.org:8011/builders/clang-ppc64be-linux-multistage/builds/2315
for example.

Reverting as per the developer's request.

llvm-svn: 295849

1 files changed, 8 insertions, 19 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f8e18e22f65..091aba35f46 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4446,8 +4446,6 @@ const Optional<ByteProvider> calculateByteProvider(SDValue Op, unsigned Index,
                : calculateByteProvider(Op->getOperand(0), Index - ByteShift,
                                        Depth + 1);
   }
-  case ISD::ANY_EXTEND:
-  case ISD::SIGN_EXTEND:
   case ISD::ZERO_EXTEND: {
     SDValue NarrowOp = Op->getOperand(0);
     unsigned NarrowBitWidth = NarrowOp.getScalarValueSizeInBits();
@@ -4455,32 +4453,22 @@ const Optional<ByteProvider> calculateByteProvider(SDValue Op, unsigned Index,
       return None;
     uint64_t NarrowByteWidth = NarrowBitWidth / 8;
 
-    if (Index >= NarrowByteWidth)
-      return Op.getOpcode() == ISD::ZERO_EXTEND
-                 ? Optional<ByteProvider>(ByteProvider::getConstantZero())
-                 : None;
-    else
-      return calculateByteProvider(NarrowOp, Index, Depth + 1);
+    return Index >= NarrowByteWidth
+               ? ByteProvider::getConstantZero()
+               : calculateByteProvider(NarrowOp, Index, Depth + 1);
   }
   case ISD::BSWAP:
     return calculateByteProvider(Op->getOperand(0), ByteWidth - Index - 1,
                                  Depth + 1);
   case ISD::LOAD: {
     auto L = cast<LoadSDNode>(Op.getNode());
-    if (L->isVolatile() || L->isIndexed())
-      return None;
 
-    unsigned NarrowBitWidth = L->getMemoryVT().getSizeInBits();
-    if (NarrowBitWidth % 8 != 0)
+    // TODO: support ext loads
+    if (L->isVolatile() || L->isIndexed() ||
+        L->getExtensionType() != ISD::NON_EXTLOAD)
       return None;
-    uint64_t NarrowByteWidth = NarrowBitWidth / 8;
 
-    if (Index >= NarrowByteWidth)
-      return L->getExtensionType() == ISD::ZEXTLOAD
-                 ? Optional<ByteProvider>(ByteProvider::getConstantZero())
-                 : None;
-    else
-      return ByteProvider::getMemory(L, Index);
+    return ByteProvider::getMemory(L, Index);
   }
   }
 
@@ -4560,6 +4548,7 @@ SDValue DAGCombiner::MatchLoadCombine(SDNode *N) {
 
     LoadSDNode *L = P->Load;
     assert(L->hasNUsesOfValue(1, 0) && !L->isVolatile() && !L->isIndexed() &&
+           (L->getExtensionType() == ISD::NON_EXTLOAD) &&
            "Must be enforced by calculateByteProvider");
     assert(L->getOffset().isUndef() && "Unindexed load must have undef offset");