[llvm] r272849 - [DSE] Hoist a redundant check to simplify logic. NFC.

[Chad Rosier via llvm-commits]

Author: mcrosier
Date: Wed Jun 15 17:17:38 2016
New Revision: 272849

URL: http://llvm.org/viewvc/llvm-project?rev=272849&view=rev
Log:
[DSE] Hoist a redundant check to simplify logic. NFC.

Modified:
    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=272849&r1=272848&r2=272849&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Wed Jun 15 17:17:38 2016
@@ -289,29 +289,22 @@ static OverwriteResult isOverwrite(const
                                    const DataLayout &DL,
                                    const TargetLibraryInfo &TLI,
                                    int64_t &EarlierOff, int64_t &LaterOff) {
+  // If we don't know the sizes of either access, then we can't do a comparison.
+  if (Later.Size == MemoryLocation::UnknownSize ||
+      Earlier.Size == MemoryLocation::UnknownSize)
+    return OverwriteUnknown;
+
   const Value *P1 = Earlier.Ptr->stripPointerCasts();
   const Value *P2 = Later.Ptr->stripPointerCasts();
 
   // If the start pointers are the same, we just have to compare sizes to see if
   // the later store was larger than the earlier store.
   if (P1 == P2) {
-    // If we don't know the sizes of either access, then we can't do a
-    // comparison.
-    if (Later.Size == MemoryLocation::UnknownSize ||
-        Earlier.Size == MemoryLocation::UnknownSize)
-      return OverwriteUnknown;
-
     // Make sure that the Later size is >= the Earlier size.
     if (Later.Size >= Earlier.Size)
       return OverwriteComplete;
   }
 
-  // Otherwise, we have to have size information, and the later store has to be
-  // larger than the earlier one.
-  if (Later.Size == MemoryLocation::UnknownSize ||
-      Earlier.Size == MemoryLocation::UnknownSize)
-    return OverwriteUnknown;
-
   // Check to see if the later store is to the entire object (either a global,
   // an alloca, or a byval/inalloca argument).  If so, then it clearly
   // overwrites any other store to the same object.