[llvm] 42c57c2 - [DSE, MemorySSA] Simplify code, EarlierAccess is be a MemoryDef (NFC).

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-08-30T21:31:57+01:00
New Revision: 42c57c294dfbd8ea82cd61c709289480f513211b

URL: https://github.com/llvm/llvm-project/commit/42c57c294dfbd8ea82cd61c709289480f513211b
DIFF: https://github.com/llvm/llvm-project/commit/42c57c294dfbd8ea82cd61c709289480f513211b.diff

LOG: [DSE,MemorySSA] Simplify code, EarlierAccess is be a MemoryDef (NFC).

After recent changes, we return early if Current is a MemoryPhi, so
EarlierAccess can only be a MemoryDef.

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 9825dfdf01cd..b2613697bfa5 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1935,24 +1935,17 @@ struct DSEState {
       }
     } while (StepAgain);
 
-    MemoryAccess *EarlierAccess = Current;
     // Accesses to objects accessible after the function returns can only be
     // eliminated if the access is killed along all paths to the exit. Collect
     // the blocks with killing (=completely overwriting MemoryDefs) and check if
     // they cover all paths from EarlierAccess to any function exit.
     SmallPtrSet<Instruction *, 16> KillingDefs;
     KillingDefs.insert(KillingDef->getMemoryInst());
+    MemoryAccess *EarlierAccess = Current;
     Instruction *EarlierMemInst =
-        isa<MemoryDef>(EarlierAccess)
-            ? cast<MemoryDef>(EarlierAccess)->getMemoryInst()
-            : nullptr;
-    LLVM_DEBUG({
-      dbgs() << "  Checking for reads of " << *EarlierAccess;
-      if (EarlierMemInst)
-        dbgs() << " (" << *EarlierMemInst << ")\n";
-      else
-        dbgs() << ")\n";
-    });
+        cast<MemoryDef>(EarlierAccess)->getMemoryInst();
+    LLVM_DEBUG(dbgs() << "  Checking for reads of " << *EarlierAccess << " ("
+                      << *EarlierMemInst << ")\n");
 
     SmallSetVector<MemoryAccess *, 32> WorkList;
     auto PushMemUses = [&WorkList](MemoryAccess *Acc) {
@@ -1964,7 +1957,7 @@ struct DSEState {
     // Optimistically collect all accesses for reads. If we do not find any
     // read clobbers, add them to the cache.
     SmallPtrSet<MemoryAccess *, 16> KnownNoReads;
-    if (!EarlierMemInst || !EarlierMemInst->mayReadFromMemory())
+    if (!EarlierMemInst->mayReadFromMemory())
       KnownNoReads.insert(EarlierAccess);
     // Check if EarlierDef may be read.
     for (unsigned I = 0; I < WorkList.size(); I++) {