Fix ClosureLifetimeFixup to insert destroys at leaking blocks

Author: meg-gupta

include/swift/SILOptimizer/Utils/InstOptUtils.h

@@ -580,7 +580,8 @@ SILValue makeValueAvailable(SILValue value, SILBasicBlock *inBlock);
 /// use blocks inside a loop relative to \p value. The client must create
 /// separate copies for any uses within the loop.
 void endLifetimeAtLeakingBlocks(SILValue value,
-                                ArrayRef<SILBasicBlock *> userBBs);
+                                ArrayRef<SILBasicBlock *> userBBs,
+                                DeadEndBlocks *deadEndBlocks = nullptr);
 
 /// Given a forwarding instruction, eliminate it if all of its users are debug
 /// instructions and ownership uses.

lib/SILOptimizer/Mandatory/ClosureLifetimeFixup.cpp

@@ -1063,6 +1063,11 @@ static bool tryExtendLifetimeToLastUse(
             deadEndBlocks->isDeadEnd(builder.getInsertionPoint()->getParent()));
         builder.createDestroyValue(loc, closureCopy, DontPoisonRefs, isDeadEnd);
       });
+
+  // Closure User may not be post-dominating the previously created copy_value.
+  // Create destroy_value at leaking blocks.
+
+  endLifetimeAtLeakingBlocks(closureCopy, {singleUser->getParent()}, deadEndBlocks);
   /*
   llvm::errs() << "after lifetime extension of\n";
   escapingClosure->dump();

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -1913,7 +1913,8 @@ bool swift::tryEliminateOnlyOwnershipUsedForwardingInst(
 // The consuming use blocks are assumed either not to inside a loop relative to
 // \p value or they must have their own copies.
 void swift::endLifetimeAtLeakingBlocks(SILValue value,
-                                       ArrayRef<SILBasicBlock *> uses) {
+                                       ArrayRef<SILBasicBlock *> uses,
+                                       DeadEndBlocks *deadEndBlocks) {
   if (!value->getFunction()->hasOwnership())
     return;
 
@@ -1926,8 +1927,14 @@ void swift::endLifetimeAtLeakingBlocks(SILValue value,
         // Insert a destroy_value in the leaking block
         auto front = postDomBlock->begin();
         SILBuilderWithScope newBuilder(front);
+        swift::IsDeadEnd_t isDeadEnd = swift::IsntDeadEnd;
+        if (deadEndBlocks) {
+          isDeadEnd = IsDeadEnd_t(deadEndBlocks->isDeadEnd(
+              newBuilder.getInsertionPoint()->getParent()));
+        }
         newBuilder.createDestroyValue(
-            RegularLocation::getAutoGeneratedLocation(), value);
+            RegularLocation::getAutoGeneratedLocation(), value, DontPoisonRefs,
+            isDeadEnd);
       });
 }
 

test/SILOptimizer/closure-lifetime-fixup.sil

@@ -410,3 +410,39 @@ bb2(%error : @owned $any Error):
   destroy_value [dead_end] %nonescaping_nothrower : $@noescape @callee_guaranteed () -> (Int, @error any Error) 
   unreachable                                     
 } 
+
+
+sil @nonthrowing : $@convention(thin) (@guaranteed @noescape @callee_guaranteed () -> (Int, @error any Error)) -> ()
+sil @throwsfn : $@convention(thin) () -> ((), @error any Error) 
+ 
+// Ensure no ownership verification error
+// CHECK-LABEL: sil [ossa] @testRethrowing : {{.*}} {
+// CHECK:         [[NOTHROWER:%[^,]+]] = function_ref @nothrower
+// CHECK:         [[THICK_NOTHROWER:%[^,]+]] = thin_to_thick_function [[NOTHROWER]]
+// CHECK:         [[THROWING_NOTHROWER:%[^,]+]] = convert_function [[THICK_NOTHROWER]]
+// CHECK:         [[NOTHROWER_COPY:%[^,]+]] = copy_value [[THROWING_NOTHROWER]]
+// CHECK:       {{bb[0-9]+}}
+// CHECK:         destroy_value [[NOTHROWER_COPY]]
+// CHECK:       {{bb[0-9]+}}
+// CHECK:         destroy_value [[NOTHROWER_COPY]]
+// CHECK-LABEL: } // end sil function 'testRethrowing'
+sil [ossa] @testRethrowing : $@convention(thin) () -> ((), @error any Error) {
+bb0:
+  %nothrower = function_ref @nothrower : $@convention(thin) () -> Int 
+  %thick_nothrower = thin_to_thick_function %nothrower : $@convention(thin) () -> Int to $@callee_guaranteed () -> Int 
+  %throwing_nothrower = convert_function %thick_nothrower : $@callee_guaranteed () -> Int to $@callee_guaranteed () -> (Int, @error any Error) 
+  %nonescaping_nothrower = convert_escape_to_noescape [not_guaranteed] %throwing_nothrower : $@callee_guaranteed () -> (Int, @error any Error) to $@noescape @callee_guaranteed () -> (Int, @error any Error)
+  %throwsfnref = function_ref @throwsfn : $@convention(thin) () -> ((), @error any Error) 
+  try_apply %throwsfnref() : $@convention(thin) () -> ((), @error any Error), normal bb1, error bb2
+
+bb1(%arg : $()):
+  %nonthrower = function_ref @nonthrowing : $@convention(thin) (@guaranteed @noescape @callee_guaranteed () -> (Int, @error any Error)) -> () 
+  apply %nonthrower(%nonescaping_nothrower) : $@convention(thin) (@guaranteed @noescape @callee_guaranteed () -> (Int, @error any Error)) -> () 
+  destroy_value %nonescaping_nothrower : $@noescape @callee_guaranteed () -> (Int, @error any Error) 
+  %8 = tuple ()                                   
+  return %8 : $()                                 
+
+bb2(%error : @owned $any Error):
+  destroy_value %nonescaping_nothrower : $@noescape @callee_guaranteed () -> (Int, @error any Error) 
+  throw %error
+}