Fix double delete in generic specialization.

We ended up adding the same instruction twice to a SmallVector of
instructions to be deleted. To avoid this, we'll track these
to-be-deleted instructions in a SmallSetVector instead.

We were also failing to add an instruction that we can delete to the set
of instructions to be deleted, so I fixed that as well.

I've added a test case, but it's currently disabled because fixing this
turned up another issue in the same code which I still need to take a
look at.

Fixes rdar://problem/25369617.

Author: rudkx

include/swift/SILOptimizer/Utils/Generics.h

@@ -36,9 +36,8 @@ namespace swift {
 ///
 /// This is the top-level entry point for specializing an existing call site.
 void trySpecializeApplyOfGeneric(
-  ApplySite Apply,
-  llvm::SmallVectorImpl<SILInstruction *> &DeadApplies,
-  llvm::SmallVectorImpl<SILFunction *> &NewFunctions);
+    ApplySite Apply, DeadInstructionSet &DeadApplies,
+    llvm::SmallVectorImpl<SILFunction *> &NewFunctions);
 
 /// Helper class to describe re-abstraction of function parameters done during
 /// specialization.

include/swift/SILOptimizer/Utils/Local.h

@@ -40,6 +40,8 @@ inline ValueBaseUserRange makeUserRange(
                             UserTransform(toUser));
 }
 
+using DeadInstructionSet = llvm::SmallSetVector<SILInstruction *, 8>;
+
 /// \brief For each of the given instructions, if they are dead delete them
 /// along with their dead operands.
 ///

lib/SILOptimizer/Transforms/GenericSpecializer.cpp

@@ -48,7 +48,7 @@ class GenericSpecializer : public SILFunctionTransform {
 } // end anonymous namespace
 
 bool GenericSpecializer::specializeAppliesInFunction(SILFunction &F) {
-  llvm::SmallVector<SILInstruction *, 8> DeadApplies;
+  DeadInstructionSet DeadApplies;
 
   for (auto &BB : F) {
     for (auto It = BB.begin(), End = BB.end(); It != End;) {

lib/SILOptimizer/Utils/Generics.cpp

@@ -385,9 +385,9 @@ static SILFunction *createReabstractionThunk(const ReabstractionInfo &ReInfo,
   return Thunk;
 }
 
-void swift::trySpecializeApplyOfGeneric(ApplySite Apply,
-                        llvm::SmallVectorImpl<SILInstruction *> &DeadApplies,
-                        llvm::SmallVectorImpl<SILFunction *> &NewFunctions) {
+void swift::trySpecializeApplyOfGeneric(
+    ApplySite Apply, DeadInstructionSet &DeadApplies,
+    llvm::SmallVectorImpl<SILFunction *> &NewFunctions) {
   assert(Apply.hasSubstitutions() && "Expected an apply with substitutions!");
 
   auto *F = cast<FunctionRefInst>(Apply.getCallee())->getReferencedFunction();
@@ -450,7 +450,7 @@ void swift::trySpecializeApplyOfGeneric(ApplySite Apply,
     NewFunctions.push_back(SpecializedF);
   }
 
-  DeadApplies.push_back(Apply.getInstruction());
+  DeadApplies.insert(Apply.getInstruction());
 
   if (replacePartialApplyWithoutReabstraction) {
     // There are some unknown users of the partial_apply. Therefore we need a
@@ -471,6 +471,7 @@ void swift::trySpecializeApplyOfGeneric(ApplySite Apply,
                                       Arguments,
                                       PAI->getType());
     PAI->replaceAllUsesWith(NewPAI);
+    DeadApplies.insert(PAI);
     return;
   }
   // Make the required changes to the call site.
@@ -486,14 +487,14 @@ void swift::trySpecializeApplyOfGeneric(ApplySite Apply,
       if (auto FAS = FullApplySite::isa(User)) {
         SILBuilder Builder(User);
         replaceWithSpecializedCallee(FAS, NewPAI, Builder, ReInfo);
-        DeadApplies.push_back(User);
+        DeadApplies.insert(FAS.getInstruction());
         continue;
       }
       if (auto *PAI = dyn_cast<PartialApplyInst>(User)) {
         // This is a partial_apply of a re-abstraction thunk. Just skip this.
         assert(PAI->getType() == NewPAI->getType());
         PAI->replaceAllUsesWith(NewPAI);
-        DeadApplies.push_back(PAI);
+        DeadApplies.insert(PAI);
       }
     }
   }

test/SILOptimizer/specialize_reabstraction.sil

@@ -0,0 +1,77 @@
+// RUN: %target-sil-opt -enable-sil-verify-all -generic-specializer %s | FileCheck %s
+// REQUIRES: rdar://25447450
+
+
+sil_stage canonical
+
+import Builtin
+import Swift
+
+public protocol RefProto {
+  associatedtype T
+  var me: Ref<Self.T> { get }
+}
+
+public final class Ref<T> : RefProto {
+  public final var me: Ref<T> { get }
+  deinit
+  init()
+}
+
+extension RefProto {
+  public func merge<U>(other: Ref<U>) -> Ref<(Self.T, U)>
+}
+
+public protocol ValProto {
+  associatedtype T
+  var me: Val<Self.T> { get }
+}
+
+extension ValProto {
+  public func merge<U>(other: Val<U>) -> Val<(Self.T, U)>
+}
+
+public struct Val<T> : ValProto {
+  public var me: Val<T> { get }
+  init()
+}
+
+sil @coerce : $@convention(thin) <T, U, V> (@owned @callee_owned (@owned Ref<T>) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<V>) -> @owned @callee_owned (Val<U>) -> Val<V>
+
+sil @merge : $@convention(method) <Self where Self : RefProto><U> (@owned Ref<U>, @in_guaranteed Self) -> @owned Ref<(Self.T, U)> {
+
+bb0(%0 : $Ref<U>, %1 : $*Self):
+  %2 = alloc_ref $Ref<(Self.T, U)>
+  strong_release %0 : $Ref<U>
+  return %2 : $Ref<(Self.T, U)>
+}
+
+sil @merge_curried : $@convention(thin) <Self where Self : RefProto><U> (@in Self) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)> {
+bb0(%0 : $*Self):
+  %1 = function_ref @merge : $@convention(method) <τ_0_0 where τ_0_0 : RefProto><τ_1_0> (@owned Ref<τ_1_0>, @in_guaranteed τ_0_0) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  %2 = partial_apply %1<Self, Self.T, U>(%0) : $@convention(method) <τ_0_0 where τ_0_0 : RefProto><τ_1_0> (@owned Ref<τ_1_0>, @in_guaranteed τ_0_0) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  return %2 : $@callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)>
+}
+
+sil [reabstraction_thunk] @reabstract : $@convention(thin) <Self where Self : ValProto><U> (@owned Ref<Self.T>, @owned @callee_owned (@in Ref<Self.T>) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)>) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)> {
+bb0(%0 : $Ref<Self.T>, %1 : $@callee_owned (@in Ref<Self.T>) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)>):
+  %2 = alloc_stack $Ref<Self.T>
+  store %0 to %2 : $*Ref<Self.T>
+  %4 = apply %1(%2) : $@callee_owned (@in Ref<Self.T>) -> @owned @callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)>
+  dealloc_stack %2 : $*Ref<Self.T>
+  return %4 : $@callee_owned (@owned Ref<U>) -> @owned Ref<(Self.T, U)>
+}
+
+sil @test : $@convention(thin) (Val<Bool>, Val<Int>) -> Val<(Bool, Int)> {
+
+bb0(%0 : $Val<Bool>, %1 : $Val<Int>):
+  %4 = function_ref @coerce : $@convention(thin) <τ_0_0, τ_0_1, τ_0_2> (@owned @callee_owned (@owned Ref<τ_0_0>) -> @owned @callee_owned (@owned Ref<τ_0_1>) -> @owned Ref<τ_0_2>) -> @owned @callee_owned (Val<τ_0_1>) -> Val<τ_0_2>
+  %5 = metatype $@thick Ref<Bool>.Type
+  %6 = function_ref @merge_curried : $@convention(thin) <τ_0_0 where τ_0_0 : RefProto><τ_1_0> (@in τ_0_0) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  %7 = partial_apply %6<Ref<Bool>, Bool, Int>() : $@convention(thin) <τ_0_0 where τ_0_0 : RefProto><τ_1_0> (@in τ_0_0) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  %8 = function_ref @reabstract : $@convention(thin) <τ_0_0 where τ_0_0 : ValProto><τ_1_0> (@owned Ref<τ_0_0.T>, @owned @callee_owned (@in Ref<τ_0_0.T>) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  %9 = partial_apply %8<Val<Bool>, Bool, Int>(%7) : $@convention(thin) <τ_0_0 where τ_0_0 : ValProto><τ_1_0> (@owned Ref<τ_0_0.T>, @owned @callee_owned (@in Ref<τ_0_0.T>) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>) -> @owned @callee_owned (@owned Ref<τ_1_0>) -> @owned Ref<(τ_0_0.T, τ_1_0)>
+  %10 = apply %4<Bool, Int, (Bool, Int)>(%9) : $@convention(thin) <τ_0_0, τ_0_1, τ_0_2> (@owned @callee_owned (@owned Ref<τ_0_0>) -> @owned @callee_owned (@owned Ref<τ_0_1>) -> @owned Ref<τ_0_2>) -> @owned @callee_owned (Val<τ_0_1>) -> Val<τ_0_2>
+  %11 = apply %10(%1) : $@callee_owned (Val<Int>) -> Val<(Bool, Int)>
+  return %11 : $Val<(Bool, Int)>
+}