[PATCH] D155406: [MemCpyOpt] implement multi BB stack-move optimization

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp:1598
+        if (LI && LI->getLoopFor(BB) != nullptr)
+          return false;
+
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Is this check needed? I would expect that this is covered by adding the successors to the reachability worklist. Then we shouldn't need LoopInfo.


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Comment at: llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp:1674
+    // create one at each exit block, but that'd be essentially semantically
+    // meaningless. If the last user is the terminator for the bb, we can insert
+    // lifetime.end marker to the immediate post-dominator. We need to create
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bb -> BB


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Comment at: llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp:1682
+        (PDom && isModOrRefSet(AA->getModRefInfo(PDom, SrcLoc))) ? PDom
+                                                                 : nullptr;
+    if (PDom && PDom->isTerminator() && PDomUser) {
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I don't get what you're doing here with AA. Why is this necessary now and wasn't needed in the single BB case?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155406/new/

https://reviews.llvm.org/D155406