Revert "Generalize alloc_stack hoisting. Remove speculative scoped instruction hoisting."

This reverts commit b777b07.

Author: MAJKFL

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LoopInvariantCodeMotion.swift

@@ -310,7 +310,7 @@ private func collectMovableInstructions(
 
         movableInstructions.loadsAndStores.append(loadInst)
       case is UncheckedOwnershipConversionInst:
-        break
+        break // TODO: Add support
       case let storeInst as StoreInst:
         switch storeInst.storeOwnership {
         case .assign:
@@ -647,10 +647,24 @@ private extension MovableInstructions {
       return false
     }
 
-    let dominatingBlocks = loop.getBlocksThatDominateAllExitingAndLatchBlocks(context)
     var changed = false
 
-    for scopedInst in scopedInsts where dominatingBlocks.contains(scopedInst.parentBlock) {
+    for scopedInst in scopedInsts {
+      if let storeBorrowInst = scopedInst as? StoreBorrowInst {
+        _ = storeBorrowInst.allocStack.hoist(outOf: loop, context)
+        
+        var sankFirst = false
+        for deallocStack in storeBorrowInst.allocStack.deallocations {
+          if sankFirst {
+            context.erase(instruction: deallocStack)
+          } else {
+            sankFirst = deallocStack.sink(outOf: loop, context)
+          }
+        }
+        
+        context.notifyInvalidatedStackNesting()
+      }
+
       guard scopedInst.hoist(outOf: loop, context) else {
         continue
       }
@@ -821,8 +835,6 @@ private extension Instruction {
   /// is not a terminator, allocation or deallocation and either a hoistable array semantics call or doesn't have memory effects.
   func canBeHoisted(outOf loop: Loop, _ context: FunctionPassContext) -> Bool {
     switch self {
-    case let allocStackInst as AllocStackInst:
-      return allocStackInst.deallocations.allSatisfy({ loop.contains(block: $0.parentBlock) })
     case is TermInst, is Allocation, is Deallocation:
       return false
     case is ApplyInst:
@@ -862,19 +874,6 @@ private extension Instruction {
         return true
       } else {
         move(before: terminator, context)
-        
-        if let allocStack = self as? AllocStackInst {
-          var sankFirst = false
-          for deallocStack in allocStack.deallocations {
-            if sankFirst {
-              context.erase(instruction: deallocStack)
-            } else {
-              sankFirst = deallocStack.sink(outOf: loop, context)
-            }
-          }
-          
-          context.notifyInvalidatedStackNesting()
-        }
       }
     }