[DAGCombiner] Exploiting more about the transformation of TransformFPLoadStorePair function

For a given floating point load / store pair, if the load value isn't used by any other operations, 
then consider transforming the pair to integer load / store operations if the target deems the transformation profitable.

And we can exploiting much more when there are other operation nodes with chain operand between the load/store pair 
so long as we keep the chain ordering original. We only replace the register used to load/store from float to integer.

I only add testcase in ARM because the TLI.isDesirableToTransformToIntegerOp hook is only enabled in ARM target.

Differential Revision: https://reviews.llvm.org/D60601

llvm-svn: 364883

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 54a52690012..2bfc3979360 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -14928,11 +14928,9 @@ SDValue DAGCombiner::ReduceLoadOpStoreWidth(SDNode *N) {
 /// load / store operations if the target deems the transformation profitable.
 SDValue DAGCombiner::TransformFPLoadStorePair(SDNode *N) {
   StoreSDNode *ST  = cast<StoreSDNode>(N);
-  SDValue Chain = ST->getChain();
   SDValue Value = ST->getValue();
   if (ISD::isNormalStore(ST) && ISD::isNormalLoad(Value.getNode()) &&
-      Value.hasOneUse() &&
-      Chain == SDValue(Value.getNode(), 1)) {
+      Value.hasOneUse()) {
     LoadSDNode *LD = cast<LoadSDNode>(Value);
     EVT VT = LD->getMemoryVT();
     if (!VT.isFloatingPoint() ||
@@ -14962,7 +14960,7 @@ SDValue DAGCombiner::TransformFPLoadStorePair(SDNode *N) {
                     LD->getPointerInfo(), LDAlign);
 
     SDValue NewST =
-        DAG.getStore(NewLD.getValue(1), SDLoc(N), NewLD, ST->getBasePtr(),
+        DAG.getStore(ST->getChain(), SDLoc(N), NewLD, ST->getBasePtr(),
                      ST->getPointerInfo(), STAlign);
 
     AddToWorklist(NewLD.getNode());