[PATCH] D105098: [DSE][NFC] Introduce "doesn't overwrite" return code for isOverwrite

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Add OR_None code to indicate that there is no overwrite. This has no any effect for current uses but will be used in one of the next patches building support for PHI translation.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105098

Files:
  llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp


Index: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -327,6 +327,7 @@
   OW_End,
   OW_PartialEarlierWithFullLater,
   OW_MaybePartial,
+  OW_None,
   OW_Unknown
 };
 
@@ -1055,7 +1056,7 @@
 
     // Can reach here only if accesses are known not to overlap. There is no
     // dedicated code to indicate no overlap so signal "unknown".
-    return OW_Unknown;
+    return OW_None;
   }
 
   bool isInvisibleToCallerAfterRet(const Value *V) {
@@ -1455,7 +1456,7 @@
                               DepWriteOffset, InstWriteOffset);
         // If Current does not write to the same object as KillingDef, check
         // the next candidate.
-        if (OR == OW_Unknown)
+        if (OR == OW_Unknown || OR == OW_None)
           continue;
         else if (OR == OW_MaybePartial) {
           // If KillingDef only partially overwrites Current, check the next
@@ -1464,6 +1465,7 @@
           // which are less likely to be removable in the end.
           if (PartialLimit <= 1) {
             WalkerStepLimit -= 1;
+            LLVM_DEBUG(dbgs() << "   ... reached partial limit ... continue with next access\n");
             continue;
           }
           PartialLimit -= 1;


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