Merge pull request swiftlang#41518 from apple/revert-41497-lexical_lifetimes/lexical_destroy_addr_hoisting/split-copy_addr

Revert "[SSADestroyHoisting] Split destroy from copy."

Author: nate-chandler

lib/SILOptimizer/Transforms/SSADestroyHoisting.cpp

@@ -754,7 +754,6 @@ void SSADestroyHoisting::run() {
   llvm::SmallVector<AllocStackInst *, 4> asis;
   llvm::SmallVector<BeginAccessInst *, 4> bais;
   llvm::SmallVector<StoreInst *, 4> sis;
-  llvm::SmallVector<CopyAddrInst *, 4> cais;
 
   // Collect the instructions that we'll be transforming.
   for (auto &block : *getFunction()) {
@@ -769,10 +768,6 @@ void SSADestroyHoisting::run() {
         if (si->getOwnershipQualifier() == StoreOwnershipQualifier::Assign) {
           sis.push_back(si);
         }
-      } else if (auto *cai = dyn_cast<CopyAddrInst>(&inst)) {
-        if (cai->isInitializationOfDest() == IsNotInitialization) {
-          cais.push_back(cai);
-        }
       }
     }
   }
@@ -809,32 +804,6 @@ void SSADestroyHoisting::run() {
     remainingDestroyAddrs.insert(dai);
     ++splitDestroys;
   }
-  // Similarly, also expand each
-  //
-  //     copy_addr to
-  //
-  // instruction into
-  //
-  //     destroy_addr
-  //     copy_addr to [initialization]
-  //
-  // sequences to create still more destroy_addrs to hoist.
-  //
-  // As above, record the newly created destroy_addrs and copy_addrs off of
-  // which they were split.  After hoisting, we'll merge them back together when
-  // possible.
-  llvm::SmallVector<std::pair<DestroyAddrInst *, CopyAddrInst *>, 8>
-      splitDestroysAndCopies;
-  for (auto *cai : cais) {
-    auto builder = SILBuilderWithScope(cai);
-    auto *dai = builder.createDestroyAddr(
-        RegularLocation::getAutoGeneratedLocation(cai->getLoc()),
-        cai->getOperand(1));
-    cai->setIsInitializationOfDest(IsInitialization);
-    splitDestroysAndCopies.push_back({dai, cai});
-    remainingDestroyAddrs.insert(dai);
-    ++splitDestroys;
-  }
 
   // We assume that the function is in reverse post order so visiting the
   // blocks and pushing begin_access as we see them and then popping them off
@@ -871,29 +840,17 @@ void SSADestroyHoisting::run() {
     if (!remainingDestroyAddrs.contains(dai))
       continue;
     auto *si = pair.second;
-    if (dai->getNextInstruction() != si)
-      continue;
-    // No stores should have been rewritten during hoisting.  Their ownership
-    // qualifiers were set to [init] when splitting off the destroy_addrs.
-    assert(si->getOwnershipQualifier() == StoreOwnershipQualifier::Init);
-    // If a newly created destroy_addr has not been hoisted from its previous
-    // location, combine it back together with the store [init] which it was
-    // split off from.
-    deleter.forceDelete(dai);
-    si->setOwnershipQualifier(StoreOwnershipQualifier::Assign);
-    --splitDestroys;
-  }
-  for (auto pair : splitDestroysAndCopies) {
-    auto *dai = pair.first;
-    if (!remainingDestroyAddrs.contains(dai))
-      continue;
-    auto *cai = pair.second;
-    if (dai->getNextInstruction() != cai)
-      continue;
-    assert(cai->isInitializationOfDest() == IsInitialization);
-    deleter.forceDelete(dai);
-    cai->setIsInitializationOfDest(IsNotInitialization);
-    --splitDestroys;
+    if (dai->getNextInstruction() == si) {
+      // No stores should have been rewritten during hoisting.  Their ownership
+      // qualifiers were set to [init] when splitting off the destroy_addrs.
+      assert(si->getOwnershipQualifier() == StoreOwnershipQualifier::Init);
+      // If a newly created destroy_addr has not been hoisted from its previous
+      // location, combine it back together with the store [init] which it was
+      // split off from.
+      deleter.forceDelete(dai);
+      si->setOwnershipQualifier(StoreOwnershipQualifier::Assign);
+      --splitDestroys;
+    }
   }
   // If there were any destroy_addrs split off of stores and not recombined
   // with them, then the function has changed.