[PATCH] D66318: [SDAG] Update generic code to conservatively check for isAtomic in addition to isVolatile

[Matt Arsenault via Phabricator via llvm-commits]

arsenm accepted this revision.
arsenm added a comment.
This revision is now accepted and ready to land.
Herald added a subscriber: wdng.

LGTM with nits



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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:14036
   StoreSDNode *ST = dyn_cast<StoreSDNode>(Chain.getNode());
-  if (!ST || ST->isVolatile())
+  // TODO: relax this restriction for unordered atomics (see D66309)
+  if (!ST || !ST->isSimple())
----------------
Capitalize comment


================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:16320
   // is dead/noop.
+  // TODO: can relax for unordered atomics (see D66309)
   if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) {
----------------
Ditto


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:16332
 
+  // TODO: can relax for unordered atomics (see D66309)
   if (StoreSDNode *ST1 = dyn_cast<StoreSDNode>(Chain)) {
----------------
Ditto


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:16464
       StoreSDNode *ST = dyn_cast<StoreSDNode>(Chain);
-      if (ST->isVolatile() || ST->isIndexed())
+      // TODO: can relax for unordered atomics (see D66309)
+      if (!ST->isSimple() || ST->isIndexed())
----------------
Ditto


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  https://reviews.llvm.org/D66318/new/

https://reviews.llvm.org/D66318