[llvm] [DSE] Apply initializes attribute to DSE (PR #107282)

[Haopeng Liu via llvm-commits]

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@@ -2311,37 +2472,41 @@ DSEState::eliminateDeadDefs(const MemoryLocationWrapper &KillingLocWrapper) {
 }
 
 bool DSEState::eliminateDeadDefs(const MemoryDefWrapper &KillingDefWrapper) {
-  if (!KillingDefWrapper.DefinedLocation.has_value()) {
+  if (KillingDefWrapper.DefinedLocations.empty()) {
     LLVM_DEBUG(dbgs() << "Failed to find analyzable write location for "
                       << *KillingDefWrapper.DefInst << "\n");
     return false;
   }
 
-  auto &KillingLocWrapper = *KillingDefWrapper.DefinedLocation;
-  LLVM_DEBUG(dbgs() << "Trying to eliminate MemoryDefs killed by "
-                    << *KillingLocWrapper.MemDef << " ("
-                    << *KillingLocWrapper.DefInst << ")\n");
-  auto [Changed, DeletedKillingLoc] = eliminateDeadDefs(KillingLocWrapper);
-
-  // Check if the store is a no-op.
-  if (!DeletedKillingLoc && storeIsNoop(KillingLocWrapper.MemDef,
-                                        KillingLocWrapper.UnderlyingObject)) {
-    LLVM_DEBUG(dbgs() << "DSE: Remove No-Op Store:\n  DEAD: "
-                      << *KillingLocWrapper.DefInst << '\n');
-    deleteDeadInstruction(KillingLocWrapper.DefInst);
-    NumRedundantStores++;
-    return true;
-  }
-  // Can we form a calloc from a memset/malloc pair?
-  if (!DeletedKillingLoc &&
-      tryFoldIntoCalloc(KillingLocWrapper.MemDef,
-                        KillingLocWrapper.UnderlyingObject)) {
-    LLVM_DEBUG(dbgs() << "DSE: Remove memset after forming calloc:\n"
-                      << "  DEAD: " << *KillingLocWrapper.DefInst << '\n');
-    deleteDeadInstruction(KillingLocWrapper.DefInst);
-    return true;
+  bool MadeChange = false;
+  for (auto &KillingLocWrapper : KillingDefWrapper.DefinedLocations) {
+    LLVM_DEBUG(dbgs() << "Trying to eliminate MemoryDefs killed by "
+                      << *KillingLocWrapper.MemDef << " ("
+                      << *KillingLocWrapper.DefInst << ")\n");
+    auto [Changed, DeletedKillingLoc] = eliminateDeadDefs(KillingLocWrapper);
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haopliu wrote:

Oh, nice catch! Is there a way to launch an offline buildbot run to validate? https://lab.llvm.org/buildbot/

https://github.com/llvm/llvm-project/pull/107282