[PATCH] D21039: Fix memory access local dominance function for live on entry

[Sebastian Pop via llvm-commits]

sebpop created this revision.
sebpop added reviewers: dberlin, george.burgess.iv.
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A memory access defined on function entry cannot be locally dominated by another memory access.
The patch was split from D19338 which exposes the problem.

Repository:
  rL LLVM

http://reviews.llvm.org/D21039

Files:
  llvm/lib/Transforms/Utils/MemorySSA.cpp

Index: llvm/lib/Transforms/Utils/MemorySSA.cpp
===================================================================
--- llvm/lib/Transforms/Utils/MemorySSA.cpp
+++ llvm/lib/Transforms/Utils/MemorySSA.cpp
@@ -623,6 +623,12 @@
 
   assert((Dominator->getBlock() == Dominatee->getBlock()) &&
          "Asking for local domination when accesses are in different blocks!");
+
+  // When Dominatee is defined on function entry, it cannot be dominated by
+  // another memory access.
+  if (isLiveOnEntryDef(Dominatee))
+    return false;
+
   // Get the access list for the block
   const AccessListType *AccessList = getBlockAccesses(Dominator->getBlock());
   AccessListType::const_reverse_iterator It(Dominator->getIterator());


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