Add target preference for GatherAllAliases max depth

[oota-llvm.git] / lib / CodeGen / SelectionDAG / DAGCombiner.cpp

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 31f0df99d47dbbf9d22b848ae34d8d1bed38f883..a1edb29e4860ba3605791d7bacf5429f857a2ca8 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1743,22 +1743,9 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
     return SDValue(N, 0);
 
   // fold (a+b) -> (a|b) iff a and b share no bits.
-  if (VT.isInteger() && !VT.isVector()) {
-    APInt LHSZero, LHSOne;
-    APInt RHSZero, RHSOne;
-    DAG.computeKnownBits(N0, LHSZero, LHSOne);
-
-    if (LHSZero.getBoolValue()) {
-      DAG.computeKnownBits(N1, RHSZero, RHSOne);
-
-      // If all possibly-set bits on the LHS are clear on the RHS, return an OR.
-      // If all possibly-set bits on the RHS are clear on the LHS, return an OR.
-      if ((RHSZero & ~LHSZero) == ~LHSZero || (LHSZero & ~RHSZero) == ~RHSZero){
-        if (!LegalOperations || TLI.isOperationLegal(ISD::OR, VT))
-          return DAG.getNode(ISD::OR, SDLoc(N), VT, N0, N1);
-      }
-    }
-  }
+  if ((!LegalOperations || TLI.isOperationLegal(ISD::OR, VT)) &&
+      VT.isInteger() && !VT.isVector() && DAG.haveNoCommonBitsSet(N0, N1))
+    return DAG.getNode(ISD::OR, SDLoc(N), VT, N0, N1);
 
   // fold (add x, shl(0 - y, n)) -> sub(x, shl(y, n))
   if (N1.getOpcode() == ISD::SHL && N1.getOperand(0).getOpcode() == ISD::SUB &&
@@ -3206,7 +3193,8 @@ SDValue DAGCombiner::visitAND(SDNode *N) {
         // be expensive (and would be wrong if the type is not byte sized).
         if (!LN0->isVolatile() && LoadedVT.bitsGT(ExtVT) && ExtVT.isRound() &&
             (!LegalOperations || TLI.isLoadExtLegal(ISD::ZEXTLOAD, LoadResultTy,
-                                                    ExtVT))) {
+                                                    ExtVT)) &&
+            TLI.shouldReduceLoadWidth(LN0, ISD::ZEXTLOAD, ExtVT)) {
           EVT PtrType = LN0->getOperand(1).getValueType();
 
           unsigned Alignment = LN0->getAlignment();
@@ -11165,6 +11153,13 @@ void DAGCombiner::getStoreMergeAndAliasCandidates(
     if (Index->getMemoryVT() != MemVT)
       break;
 
+    // We do not allow under-aligned stores in order to prevent
+    // overriding stores. NOTE: this is a bad hack. Alignment SHOULD
+    // be irrelevant here; what MATTERS is that we not move memory
+    // operations that potentially overlap past each-other.
+    if (Index->getAlignment() < MemVT.getStoreSize())
+      break;
+
     // We found a potential memory operand to merge.
     StoreNodes.push_back(MemOpLink(Index, Ptr.Offset, Seq++));
 
@@ -11249,12 +11244,18 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) {
   if (StoreNodes.size() < 2)
     return false;
 
-  // Sort the memory operands according to their distance from the base pointer.
+  // Sort the memory operands according to their distance from the
+  // base pointer.  As a secondary criteria: make sure stores coming
+  // later in the code come first in the list. This is important for
+  // the non-UseAA case, because we're merging stores into the FINAL
+  // store along a chain which potentially contains aliasing stores.
+  // Thus, if there are multiple stores to the same address, the last
+  // one can be considered for merging but not the others.
   std::sort(StoreNodes.begin(), StoreNodes.end(),
             [](MemOpLink LHS, MemOpLink RHS) {
     return LHS.OffsetFromBase < RHS.OffsetFromBase ||
            (LHS.OffsetFromBase == RHS.OffsetFromBase &&
-            LHS.SequenceNum > RHS.SequenceNum);
+            LHS.SequenceNum < RHS.SequenceNum);
   });
 
   // Scan the memory operations on the chain and find the first non-consecutive
@@ -14454,7 +14455,7 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
     // FIXME: The depth check could be made to return the last non-aliasing
     // chain we found before we hit a tokenfactor rather than the original
     // chain.
-    if (Depth > 6) {
+    if (Depth > TLI.getGatherAllAliasesMaxDepth()) {
       Aliases.clear();
       Aliases.push_back(OriginalChain);
       return;