Avoid calling getEnclosingBlock

While performing analysis for flush elimination, LocalFlushElimination::examineNode called TR::TreeTop::getEnclosingBlock on the current TR::TreeTop. As that method walks through the linked list chaining together the TR::TreeTops to find the corresponding BBStart, calling it in nested loops becomes very expensive when large blocks are encountered. Fixed this by passing the current block as an argument to LocalFlushElimination::examineNode Signed-off-by: Henry Zongaro <[email protected]>
eclipse-openj9 · Dec 12, 2022 · 42b0411 · 42b0411
1 parent 7cafd4b
commit 42b0411
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diff --git a/runtime/compiler/optimizer/EscapeAnalysis.cpp b/runtime/compiler/optimizer/EscapeAnalysis.cpp
@@ -9153,7 +9153,7 @@ int32_t TR_LocalFlushElimination::perform()
          _allocationInfo->empty();
          }
 
-      examineNode(node, treeTop, visited);
+      examineNode(node, treeTop, block, visited);
       }
 
    FlushCandidate *flushCandidate;
@@ -9174,7 +9174,7 @@ int32_t TR_LocalFlushElimination::perform()
    }
 
 
-bool TR_LocalFlushElimination::examineNode(TR::Node *node, TR::TreeTop *tt, TR::NodeChecklist& visited)
+bool TR_LocalFlushElimination::examineNode(TR::Node *node, TR::TreeTop *tt, TR::Block *currBlock, TR::NodeChecklist& visited)
    {
    if (visited.contains(node))
       return true;
@@ -9356,7 +9356,7 @@ bool TR_LocalFlushElimination::examineNode(TR::Node *node, TR::TreeTop *tt, TR::
                   {
                   if (reachingFlushCandidate->isOptimallyPlaced() ||
                      reachingFlushCandidate->getFlush()->getNode()->getAllocation() == NULL ||
-                     reachingFlushCandidate->getBlockNum() != tt->getEnclosingBlock()->getNumber())
+                     reachingFlushCandidate->getBlockNum() != currBlock->getNumber())
                      continue;
                   reachingCandidate = getCandidate(_candidates, reachingFlushCandidate);
                   if (!reachingCandidate)
@@ -9531,7 +9531,7 @@ bool TR_LocalFlushElimination::examineNode(TR::Node *node, TR::TreeTop *tt, TR::
       {
       TR::Node *child = node->getChild(i);
 
-      if (!examineNode(child, tt, visited))
+      if (!examineNode(child, tt, currBlock, visited))
          return false;
       }
 

diff --git a/runtime/compiler/optimizer/EscapeAnalysis.hpp b/runtime/compiler/optimizer/EscapeAnalysis.hpp
@@ -803,7 +803,7 @@ class TR_LocalFlushElimination
    TR_LocalFlushElimination(TR_EscapeAnalysis *, int32_t numAllocations);
 
    virtual int32_t perform();
-   bool examineNode(TR::Node *, TR::TreeTop *, TR::NodeChecklist& visited);
+   bool examineNode(TR::Node *, TR::TreeTop *, TR::Block *, TR::NodeChecklist& visited);
 
    TR::Optimizer *        optimizer()                     { return _escapeAnalysis->optimizer(); }
    TR::Compilation *        comp()                          { return _escapeAnalysis->comp(); }