Merge pull request swiftlang#68316 from eeckstein/fix-arc-sequence-opt-complexity

AliasAnalysis: use a complexity limit for the isObjReleased function

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Analysis/AliasAnalysis.swift

@@ -56,16 +56,20 @@ struct AliasAnalysis {
       },
 
       // isObjReleasedFn
-      { (bridgedCtxt: BridgedPassContext, bridgedObj: BridgedValue, bridgedInst: BridgedInstruction) -> Bool in
+      { (bridgedCtxt: BridgedPassContext, bridgedObj: BridgedValue, bridgedInst: BridgedInstruction, complexityBudget: Int) -> Bool in
         let context = FunctionPassContext(_bridged: bridgedCtxt)
         let inst = bridgedInst.instruction
         let obj = bridgedObj.value
         let path = SmallProjectionPath(.anyValueFields)
         if let apply = inst as? ApplySite {
-          let effect = getOwnershipEffect(of: apply, for: obj, path: path, context)
+          // Workaround for quadratic complexity in ARCSequenceOpts.
+          // We need to use an ever lower budget to not get into noticable compile time troubles.
+          let budget = complexityBudget / 10
+          let effect = getOwnershipEffect(of: apply, for: obj, path: path, complexityBudget: budget, context)
           return effect.destroy
         }
-        return obj.at(path).isEscaping(using: EscapesToInstructionVisitor(target: inst, isAddress: false), context)
+        return obj.at(path).isEscaping(using: EscapesToInstructionVisitor(target: inst, isAddress: false),
+                                       complexityBudget: complexityBudget, context)
       },
 
       // isAddrVisibleFromObj
@@ -159,9 +163,10 @@ private func getMemoryEffect(ofBuiltin builtin: BuiltinInst, for address: Value,
   }
 }
 
-private func getOwnershipEffect(of apply: ApplySite, for value: Value, path: SmallProjectionPath, _ context: FunctionPassContext) -> SideEffects.Ownership {
+private func getOwnershipEffect(of apply: ApplySite, for value: Value, path: SmallProjectionPath,
+                                complexityBudget: Int, _ context: FunctionPassContext) -> SideEffects.Ownership {
   let visitor = SideEffectsVisitor(apply: apply, calleeAnalysis: context.calleeAnalysis, isAddress: false)
-  if let result = value.at(path).visit(using: visitor, context) {
+  if let result = value.at(path).visit(using: visitor, complexityBudget: complexityBudget, context) {
     // The resulting effects are the argument effects to which `value` escapes to.
     return result.ownership
   } else {

SwiftCompilerSources/Sources/Optimizer/Utilities/EscapeUtils.swift

@@ -99,8 +99,10 @@ extension ProjectedValue {
   /// it returns the `result` of the `visitor`, if the projected value does not escape.
   /// Returns nil, if the projected value escapes.
   ///
-  func visit<V: EscapeVisitorWithResult>(using visitor: V, _ context: some Context) -> V.Result? {
-    var walker = EscapeWalker(visitor: visitor, context)
+  func visit<V: EscapeVisitorWithResult>(using visitor: V,
+                                         complexityBudget: Int = Int.max,
+                                         _ context: some Context) -> V.Result? {
+    var walker = EscapeWalker(visitor: visitor, complexityBudget: complexityBudget, context)
     if walker.walkUp(addressOrValue: value, path: path.escapePath) == .abortWalk {
       return nil
     }

include/swift/SILOptimizer/OptimizerBridging.h

@@ -36,7 +36,7 @@ struct BridgedAliasAnalysis {
   typedef swift::MemoryBehavior (* _Nonnull GetMemEffectFn)(
         BridgedPassContext context, BridgedValue, BridgedInstruction, SwiftInt);
   typedef bool (* _Nonnull Escaping2InstFn)(
-        BridgedPassContext context, BridgedValue, BridgedInstruction);
+        BridgedPassContext context, BridgedValue, BridgedInstruction, SwiftInt);
   typedef bool (* _Nonnull Escaping2ValFn)(
         BridgedPassContext context, BridgedValue, BridgedValue);
   typedef bool (* _Nonnull Escaping2ValIntFn)(

lib/SILOptimizer/Analysis/AliasAnalysis.cpp

@@ -726,7 +726,8 @@ MemoryBehavior AliasAnalysis::getMemoryEffectOnEscapedAddress(
 
 bool AliasAnalysis::isObjectReleasedByInst(SILValue obj, SILInstruction *inst) {
   if (isObjReleasedFunction) {
-    return isObjReleasedFunction({PM->getSwiftPassInvocation()}, {obj}, {inst->asSILNode()}) != 0;
+    return isObjReleasedFunction({PM->getSwiftPassInvocation()}, {obj}, {inst->asSILNode()},
+                                 getComplexityBudget(obj)) != 0;
   }
   return true;
 }