[pmo] Simplify code by inverting an if check.

lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp

@@ -1273,35 +1273,50 @@ bool AllocOptimize::tryToRemoveDeadAllocation() {
     }
   }
 
-  // If the memory object has non-trivial type, then removing the deallocation
-  // will drop any releases.  Check that there is nothing preventing removal.
+  // If our memory is trivially typed, we can just remove it without needing to
+  // consider if the stored value needs to be destroyed. So at this point,
+  // delete the memory!
+  if (MemoryType.isTrivial(Module)) {
+    LLVM_DEBUG(llvm::dbgs() << "*** Removing autogenerated trivial allocation: "
+                            << *TheMemory);
+
+    // If it is safe to remove, do it.  Recursively remove all instructions
+    // hanging off the allocation instruction, then return success.  Let the
+    // caller remove the allocation itself to avoid iterator invalidation.
+    eraseUsesOfInstruction(TheMemory);
+
+    return true;
+  }
+
+  // Otherwise removing the deallocation will drop any releases.  Check that
+  // there is nothing preventing removal.
   llvm::SmallVector<unsigned, 8> DestroyAddrIndices;
   llvm::SmallVector<AvailableValue, 32> AvailableValueList;
   llvm::SmallVector<unsigned, 8> AvailableValueStartOffsets;
 
-  if (!MemoryType.isTrivial(Module)) {
-    for (auto P : llvm::enumerate(Releases)) {
-      auto *R = P.value();
-      if (R == nullptr)
-        continue;
-
-      // We stash all of the destroy_addr that we see.
-      if (auto *DAI = dyn_cast<DestroyAddrInst>(R)) {
-        AvailableValueStartOffsets.push_back(AvailableValueList.size());
-        // Make sure we can actually promote this destroy addr. If we can not,
-        // then we must bail. In order to not gather available values twice, we
-        // gather the available values here that we will use to promote the
-        // values.
-        if (!canPromoteDestroyAddr(DAI, AvailableValueList))
-          return false;
-        DestroyAddrIndices.push_back(P.index());
-        continue;
-      }
+  for (auto P : llvm::enumerate(Releases)) {
+    auto *R = P.value();
+    if (R == nullptr)
+      continue;
 
-      LLVM_DEBUG(llvm::dbgs() << "*** Failed to remove autogenerated alloc: "
-                 "kept alive by release: " << *R);
-      return false;
+    // We stash all of the destroy_addr that we see.
+    if (auto *DAI = dyn_cast<DestroyAddrInst>(R)) {
+      AvailableValueStartOffsets.push_back(AvailableValueList.size());
+      // Make sure we can actually promote this destroy addr. If we can not,
+      // then we must bail. In order to not gather available values twice, we
+      // gather the available values here that we will use to promote the
+      // values.
+      if (!canPromoteDestroyAddr(DAI, AvailableValueList))
+        return false;
+      DestroyAddrIndices.push_back(P.index());
+      continue;
     }
+
+    LLVM_DEBUG(llvm::dbgs()
+               << "*** Failed to remove autogenerated non-trivial alloc: "
+                  "kept alive by release: "
+               << *R);
+    return false;
   }
 
   // If we reached this point, we can promote all of our destroy_addr.
@@ -1324,7 +1339,7 @@ bool AllocOptimize::tryToRemoveDeadAllocation() {
     Releases[DestroyAddrIndex] = nullptr;
   }
 
-  LLVM_DEBUG(llvm::dbgs() << "*** Removing autogenerated alloc_stack: "
+  LLVM_DEBUG(llvm::dbgs() << "*** Removing autogenerated non-trivial alloc: "
                           << *TheMemory);
 
   // If it is safe to remove, do it.  Recursively remove all instructions