PPC: Add a isConsecutiveLS utility function

isConsecutiveLS is a slightly more general form of
SelectionDAG::isConsecutiveLoad. Aside from also handling stores, it also does
not assume equality of the chain operands is necessary. In the case of the PPC
backend, this chain condition is checked in a more general way by the
surrounding code.

Mostly, this part of the refactoring in preparation for supporting optimized
unaligned stores.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182723 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 2 deletions

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 87b63a8f0f..ddf31bdd8c 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -6781,6 +6781,46 @@ SDValue PPCTargetLowering::DAGCombineFastRecipFSQRT(SDValue Op,
   return SDValue();
 }
 
+// Like SelectionDAG::isConsecutiveLoad, but also works for stores, and does
+// not enforce equality of the chain operands.
+static bool isConsecutiveLS(LSBaseSDNode *LS, LSBaseSDNode *Base,
+                            unsigned Bytes, int Dist,
+                            SelectionDAG &DAG) {
+  EVT VT = LS->getMemoryVT();
+  if (VT.getSizeInBits() / 8 != Bytes)
+    return false;
+
+  SDValue Loc = LS->getBasePtr();
+  SDValue BaseLoc = Base->getBasePtr();
+  if (Loc.getOpcode() == ISD::FrameIndex) {
+    if (BaseLoc.getOpcode() != ISD::FrameIndex)
+      return false;
+    const MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
+    int FI  = cast<FrameIndexSDNode>(Loc)->getIndex();
+    int BFI = cast<FrameIndexSDNode>(BaseLoc)->getIndex();
+    int FS  = MFI->getObjectSize(FI);
+    int BFS = MFI->getObjectSize(BFI);
+    if (FS != BFS || FS != (int)Bytes) return false;
+    return MFI->getObjectOffset(FI) == (MFI->getObjectOffset(BFI) + Dist*Bytes);
+  }
+
+  // Handle X+C
+  if (DAG.isBaseWithConstantOffset(Loc) && Loc.getOperand(0) == BaseLoc &&
+      cast<ConstantSDNode>(Loc.getOperand(1))->getSExtValue() == Dist*Bytes)
+    return true;
+
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+  const GlobalValue *GV1 = NULL;
+  const GlobalValue *GV2 = NULL;
+  int64_t Offset1 = 0;
+  int64_t Offset2 = 0;
+  bool isGA1 = TLI.isGAPlusOffset(Loc.getNode(), GV1, Offset1);
+  bool isGA2 = TLI.isGAPlusOffset(BaseLoc.getNode(), GV2, Offset2);
+  if (isGA1 && isGA2 && GV1 == GV2)
+    return Offset1 == (Offset2 + Dist*Bytes);
+  return false;
+}
+
 // Return true is there is a nearyby consecutive load to the one provided
 // (regardless of alignment). We search up and down the chain, looking though
 // token factors and other loads (but nothing else). As a result, a true
@@ -6803,7 +6843,7 @@ static bool findConsecutiveLoad(LoadSDNode *LD, SelectionDAG &DAG) {
       continue;
 
     if (LoadSDNode *ChainLD = dyn_cast<LoadSDNode>(ChainNext)) {
-      if (DAG.isConsecutiveLoad(ChainLD, LD, VT.getStoreSize(), 1))
+      if (isConsecutiveLS(ChainLD, LD, VT.getStoreSize(), 1, DAG))
         return true;
 
       if (!Visited.count(ChainLD->getChain().getNode()))
@@ -6835,7 +6875,7 @@ static bool findConsecutiveLoad(LoadSDNode *LD, SelectionDAG &DAG) {
         continue;
 
       if (LoadSDNode *ChainLD = dyn_cast<LoadSDNode>(LoadRoot))
-        if (DAG.isConsecutiveLoad(ChainLD, LD, VT.getStoreSize(), 1))
+        if (isConsecutiveLS(ChainLD, LD, VT.getStoreSize(), 1, DAG))
           return true;
 
       for (SDNode::use_iterator UI = LoadRoot->use_begin(),