Fix lifetime of intermediate phis created by RLE

We were adjusting the lifetime of the final phi created by the
SSAUpdater. The intermediate phi's lifetime needs to be adjusted as
well.

Author: meg-gupta

include/swift/SILOptimizer/Utils/InstOptUtils.h

@@ -703,6 +703,10 @@ makeCopiedValueAvailable(SILValue value, SILBasicBlock *inBlock);
 SILValue
 makeNewValueAvailable(SILValue value, SILBasicBlock *inBlock);
 
+/// Given an ssa value \p value, create destroy_values at leaking blocks
+void endLifetimeAtLeakingBlocks(SILValue value,
+                                ArrayRef<SILBasicBlock *> userBBs);
+
 /// Given a forwarding instruction, eliminate it if all of its users are debug
 /// instructions and ownership uses.
 bool tryEliminateOnlyOwnershipUsedForwardingInst(

lib/SILOptimizer/Transforms/RedundantLoadElimination.cpp

@@ -1342,11 +1342,26 @@ SILValue RLEContext::computePredecessorLocationValue(SILBasicBlock *BB,
           .getObjectType(),
       Values[0].second.getOwnershipKind());
 
+  SmallVector<SILPhiArgument *, 8> insertedPhis;
+  Updater.setInsertedPhis(&insertedPhis);
+
   for (auto V : Values) {
     Updater.addAvailableValue(V.first, V.second);
   }
 
   auto Val = Updater.getValueInMiddleOfBlock(BB);
+
+  for (auto *phi : insertedPhis) {
+    if (phi == Val) {
+      continue;
+    }
+    // Fix lifetime of intermediate phis
+    SmallVector<SILBasicBlock *, 4> userBBs;
+    for (auto use : phi->getUses()) {
+      userBBs.push_back(use->getParentBlock());
+    }
+    endLifetimeAtLeakingBlocks(phi, userBBs);
+  }
   return makeNewValueAvailable(Val, BB);
 }
 

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -2060,3 +2060,22 @@ bool swift::tryEliminateOnlyOwnershipUsedForwardingInst(
   callbacks.deleteInst(forwardingInst);
   return true;
 }
+
+void swift::endLifetimeAtLeakingBlocks(SILValue value,
+                                       ArrayRef<SILBasicBlock *> uses) {
+  if (!value->getFunction()->hasOwnership())
+    return;
+
+  if (value.getOwnershipKind() != OwnershipKind::Owned)
+    return;
+
+  findJointPostDominatingSet(
+      value->getParentBlock(), uses, [&](SILBasicBlock *loopBlock) {},
+      [&](SILBasicBlock *postDomBlock) {
+        // Insert a destroy_value in the leaking block
+        auto front = postDomBlock->begin();
+        SILBuilderWithScope newBuilder(front);
+        newBuilder.createDestroyValue(
+            RegularLocation::getAutoGeneratedLocation(), value);
+      });
+}

test/SILOptimizer/redundant_load_elim_ossa_complex.sil

@@ -771,3 +771,50 @@ bb7:
   return %val1 : $Klass
 }
 
+// CHECK-LABEL: @rle_fixlifetimeof_intermediate_phis :
+// CHECK: load
+// CHECK-NOT: load
+// CHECK-LABEL: end sil function 'rle_fixlifetimeof_intermediate_phis'
+sil [ossa] @rle_fixlifetimeof_intermediate_phis : $@convention(thin) (@in NonTrivialStruct, @owned Klass, @owned Klass) -> @owned Klass {
+bb0(%0 : $*NonTrivialStruct, %1 : @owned $Klass, %2 : @owned $Klass):
+  %ele = struct_element_addr %0 : $*NonTrivialStruct, #NonTrivialStruct.val
+  %val1 = load [copy] %ele : $*Klass
+  cond_br undef, bb1, bb2
+
+bb1:
+  store %2 to [assign] %ele : $*Klass
+  br bb3
+
+bb2:
+  destroy_value %2 : $Klass
+  br bb3
+
+bb3:
+  cond_br undef, bb4, bb8
+
+bb4:
+  cond_br undef, bb5, bb6
+
+bb5:
+  %val2 = load [copy] %ele : $*Klass
+  destroy_value %val2 : $Klass
+  store %1 to [assign] %ele : $*Klass
+  br bb7
+
+bb6:
+  destroy_value %1 : $Klass
+  br bb7
+
+bb7:
+  br bb9
+
+bb8:
+  destroy_value %1 : $Klass
+  br bb9
+
+bb9:
+  %val3 = load [take] %ele : $*Klass
+  destroy_value %val3 : $Klass
+  return %val1 : $Klass
+}
+