[llvm] r304934 - [DAG] Improve Store Merge candidate pruning. NFC.

[Nirav Dave via llvm-commits]

Author: niravd
Date: Wed Jun  7 13:51:56 2017
New Revision: 304934

URL: http://llvm.org/viewvc/llvm-project?rev=304934&view=rev
Log:
[DAG] Improve Store Merge candidate pruning. NFC.

When considering merging stores values are the results of loads only
consider stores whose values come from loads from the same base.

This fixes much of the longer compile times in PR33330.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=304934&r1=304933&r2=304934&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Jun  7 13:51:56 2017
@@ -12488,12 +12488,18 @@ void DAGCombiner::getStoreMergeCandidate
   if (BasePtr.Base.isUndef())
     return;
 
-  bool IsLoadSrc = isa<LoadSDNode>(St->getValue());
   bool IsConstantSrc = isa<ConstantSDNode>(St->getValue()) ||
                        isa<ConstantFPSDNode>(St->getValue());
   bool IsExtractVecSrc =
       (St->getValue().getOpcode() == ISD::EXTRACT_VECTOR_ELT ||
        St->getValue().getOpcode() == ISD::EXTRACT_SUBVECTOR);
+  bool IsLoadSrc = isa<LoadSDNode>(St->getValue());
+  BaseIndexOffset LBasePtr;
+  // Match on loadbaseptr if relevant.
+  if (IsLoadSrc)
+    LBasePtr = BaseIndexOffset::match(
+        cast<LoadSDNode>(St->getValue())->getBasePtr(), DAG);
+
   auto CandidateMatch = [&](StoreSDNode *Other, BaseIndexOffset &Ptr) -> bool {
     if (Other->isVolatile() || Other->isIndexed())
       return false;
@@ -12502,9 +12508,15 @@ void DAGCombiner::getStoreMergeCandidate
       if (!(MemVT.isInteger() && MemVT.bitsEq(Other->getMemoryVT()) &&
             isa<ConstantFPSDNode>(Other->getValue())))
         return false;
-    if (IsLoadSrc)
-      if (!isa<LoadSDNode>(Other->getValue()))
+    if (IsLoadSrc) {
+      // The Load's Base Ptr must also match
+      if (LoadSDNode *OtherLd = dyn_cast<LoadSDNode>(Other->getValue())) {
+        auto LPtr = BaseIndexOffset::match(OtherLd->getBasePtr(), DAG);
+        if (!(LBasePtr.equalBaseIndex(LPtr)))
+          return false;
+      } else
         return false;
+    }
     if (IsConstantSrc)
       if (!(isa<ConstantSDNode>(Other->getValue()) ||
             isa<ConstantFPSDNode>(Other->getValue())))