Merge pull request #85784 from eeckstein/fix-sil-combine-6.3

[6.3] SILCombine: fix propagation of concrete existentials in enums

Author: eeckstein

include/swift/SILOptimizer/Utils/InstOptUtils.h

@@ -213,14 +213,6 @@ castValueToABICompatibleType(SILBuilder *builder, SILPassManager *pm,
 /// ```
 bool layoutIsTypeDependent(NominalTypeDecl *decl);
 
-/// Peek through trivial Enum initialization, typically for pointless
-/// Optionals.
-///
-/// The returned InitEnumDataAddr dominates the given
-/// UncheckedTakeEnumDataAddrInst.
-InitEnumDataAddrInst *
-findInitAddressForTrivialEnum(UncheckedTakeEnumDataAddrInst *utedai);
-
 /// Returns a project_box if it is the next instruction after \p ABI and
 /// and has \p ABI as operand. Otherwise it creates a new project_box right
 /// after \p ABI and returns it.

lib/SILOptimizer/Utils/Existential.cpp

@@ -171,20 +171,6 @@ static SILInstruction *getStackInitInst(SILValue allocStackAddr,
   if (auto *ASI = dyn_cast<AllocStackInst>(CAI->getSrc()))
     return getStackInitInst(ASI, CAI, isCopied);
 
-  // Peek through a stack location holding an Enum.
-  //   %stack_adr = alloc_stack
-  //   %data_adr  = init_enum_data_addr %stk_adr
-  //   %enum_adr  = inject_enum_addr %stack_adr
-  //   %copy_src  = unchecked_take_enum_data_addr %enum_adr
-  // Replace %copy_src with %data_adr and recurse.
-  //
-  // TODO: a general Optional elimination sil-combine could
-  // supersede this check.
-  if (auto *UTEDAI = dyn_cast<UncheckedTakeEnumDataAddrInst>(CAI->getSrc())) {
-    if (InitEnumDataAddrInst *IEDAI = findInitAddressForTrivialEnum(UTEDAI))
-      return getStackInitInst(IEDAI, CAI, isCopied);
-  }
-
   // Check if the CAISrc is a global_addr.
   if (auto *GAI = dyn_cast<GlobalAddrInst>(CAI->getSrc()))
     return findInitExistentialFromGlobalAddr(GAI, CAI);

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -886,55 +886,6 @@ ProjectBoxInst *swift::getOrCreateProjectBox(AllocBoxInst *abi,
   return builder.createProjectBox(abi->getLoc(), abi, index);
 }
 
-// Peek through trivial Enum initialization, typically for pointless
-// Optionals.
-//
-// Given an UncheckedTakeEnumDataAddrInst, check that there are no
-// other uses of the Enum value and return the address used to initialized the
-// enum's payload:
-//
-//   %stack_adr = alloc_stack
-//   %data_adr  = init_enum_data_addr %stk_adr
-//   %enum_adr  = inject_enum_addr %stack_adr
-//   %copy_src  = unchecked_take_enum_data_addr %enum_adr
-//   dealloc_stack %stack_adr
-//   (No other uses of %stack_adr.)
-InitEnumDataAddrInst *
-swift::findInitAddressForTrivialEnum(UncheckedTakeEnumDataAddrInst *utedai) {
-  auto *asi = dyn_cast<AllocStackInst>(utedai->getOperand());
-  if (!asi)
-    return nullptr;
-
-  InjectEnumAddrInst *singleInject = nullptr;
-  InitEnumDataAddrInst *singleInit = nullptr;
-  for (auto use : asi->getUses()) {
-    auto *user = use->getUser();
-    if (user == utedai)
-      continue;
-
-    // If there is a single init_enum_data_addr and a single inject_enum_addr,
-    // those instructions must dominate the unchecked_take_enum_data_addr.
-    // Otherwise the enum wouldn't be initialized on all control flow paths.
-    if (auto *inj = dyn_cast<InjectEnumAddrInst>(user)) {
-      if (singleInject)
-        return nullptr;
-      singleInject = inj;
-      continue;
-    }
-
-    if (auto *init = dyn_cast<InitEnumDataAddrInst>(user)) {
-      if (singleInit)
-        return nullptr;
-      singleInit = init;
-      continue;
-    }
-
-    if (isa<DeallocStackInst>(user) || isa<DebugValueInst>(user))
-      continue;
-  }
-  return singleInit;
-}
-
 //===----------------------------------------------------------------------===//
 //                              Closure Deletion
 //===----------------------------------------------------------------------===//

test/SILOptimizer/sil_combine_concrete_existential.sil

@@ -786,6 +786,39 @@ bb0(%0 : $S):
   return %20 : $()
 }
 
+protocol Q2 {
+  func f()
+}
+
+struct S2 : Q2 {
+  func f()
+}
+
+// CHECK-LABEL: sil [ossa] @overridden_enum_in_alloc_stack :
+// CHECK:         witness_method $@opened
+// CHECK-LABEL: } // end sil function 'overridden_enum_in_alloc_stack'
+sil [ossa] @overridden_enum_in_alloc_stack : $@convention(thin) (S2, @in_guaranteed Optional<any Q2>) -> () {
+bb0(%0 : $S2, %1 : $*Optional<any Q2>):
+  %2 = alloc_stack $Optional<any Q2>
+  %3 = init_enum_data_addr %2, #Optional.some!enumelt
+  %4 = init_existential_addr %3, $S2
+  store %0 to [trivial] %4
+  inject_enum_addr %2, #Optional.some!enumelt
+  copy_addr %1 to %2
+  %8 = unchecked_take_enum_data_addr %2, #Optional.some!enumelt
+  %9 = alloc_stack $any Q2
+  copy_addr %8 to [init] %9
+  %11 = open_existential_addr immutable_access %9 to $*@opened("9EED66EA-C9C5-11F0-85FF-0EA13E3AABB2", any Q2) Self
+  %12 = witness_method $@opened("9EED66EA-C9C5-11F0-85FF-0EA13E3AABB2", any Q2) Self, #Q2.f : <Self where Self : Q2> (Self) -> () -> (), %11 : $*@opened("9EED66EA-C9C5-11F0-85FF-0EA13E3AABB2", any Q2) Self : $@convention(witness_method: Q2) <τ_0_0 where τ_0_0 : Q2> (@in_guaranteed τ_0_0) -> ()
+  %13 = apply %12<@opened("9EED66EA-C9C5-11F0-85FF-0EA13E3AABB2", any Q2) Self>(%11) : $@convention(witness_method: Q2) <τ_0_0 where τ_0_0 : Q2> (@in_guaranteed τ_0_0) -> ()
+  destroy_addr %9
+  dealloc_stack %9
+  destroy_addr %2
+  dealloc_stack %2
+  %18 = tuple ()
+  return %18
+}
+
 sil_vtable SubscriptionViewControllerBuilder {}
 sil_vtable SubscriptionViewController {}
 sil_vtable ViewController  {}