[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304934 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0cf2ab2a62e08e51c6d49f2a172ed09ea8b2ae56..a0967f574006bfc1c714ceed2b8f3854d2d235e5 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12488,12 +12488,18 @@ void DAGCombiner::getStoreMergeCandidates(
   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::getStoreMergeCandidates(
       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())))