Fix AllocBoxToStack to handle mark_dependence[_addr]

Handle the easy case in which the promoted box is the base operand of a
mark_dep. This requires nothing more than setting the base operand to the new
stack address.

Required for move-only checking. Otherwise, we get an incredibly bizarre
compiler error: noncopyable 'foo' cannot be consumed when captured by an
escaping closure

Fixes rdar://154519148 (Returning non-copyable type after accessing borrowed
field emits incorrect error about escaped closure capturing the noncopyable)

Author: atrick

include/swift/SIL/SILInstruction.h

@@ -8964,6 +8964,21 @@ class MarkDependenceInstruction {
     return SILValue();
   }
 
+  void setBase(SILValue newVal) {
+    if (inst) {
+      switch (inst->getKind()) {
+      case SILInstructionKind::MarkDependenceInst:
+        cast<MarkDependenceInst>(inst)->setBase(newVal);
+        break;
+      case SILInstructionKind::MarkDependenceAddrInst:
+        cast<MarkDependenceAddrInst>(inst)->setBase(newVal);
+        break;
+      default:
+        break;
+      }
+    }
+  }
+
   SILValue getDependent() const {
     if (inst) {
       switch (inst->getKind()) {

lib/SILOptimizer/Transforms/AllocBoxToStack.cpp

@@ -400,6 +400,13 @@ static SILInstruction *recursivelyFindBoxOperandsPromotableToAddress(
         isa<EndBorrowInst>(User))
       continue;
 
+    // mark_dependence base value uses will be directly converted to base
+    // address uses.
+    if (auto mdi = MarkDependenceInstruction(User)) {
+      if (Op->get() == mdi.getBase())
+        continue;
+    }
+
     // If our user instruction is a copy_value or a mark_uninitialized, visit
     // the users recursively.
     if (isa<MarkUninitializedInst>(User) || isa<CopyValueInst>(User) ||
@@ -738,6 +745,12 @@ static bool rewriteAllocBoxAsAllocStack(AllocBoxInst *ABI) {
       Inst->eraseFromParent();
       continue;
     }
+    // mark_dependence base value uses will be directly converted to base
+    // address uses.
+    if (auto mdi = MarkDependenceInstruction(User)) {
+      mdi.setBase(StackBox);
+      continue;
+    }
 
     assert(isa<StrongReleaseInst>(User) || isa<StrongRetainInst>(User) ||
            isa<DeallocBoxInst>(User) || isa<ProjectBoxInst>(User) ||

test/SILOptimizer/allocbox_to_stack_ne.sil

@@ -0,0 +1,66 @@
+// RUN: %target-sil-opt -enable-experimental-feature LifetimeDependence -allocbox-to-stack %s | %FileCheck %s
+
+import Swift
+import Builtin
+
+public struct View : ~Escapable {
+  let _ptr: UnsafeRawPointer
+}
+
+sil [ossa] @initFn : $@convention(method) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @owned View
+sil [ossa] @initFnAddr : $@convention(thin) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @out View 
+
+// CHECK-LABEL:  sil [ossa] @testBoxedParam :
+// CHECK-NOT: alloc_box
+// CHECK-LABEL: } // end sil function 'testBoxedParam'
+sil [ossa] @testBoxedParam : $@convention(thin) (@owned View) -> @lifetime(copy 0) @owned View {
+bb0(%0 : @noImplicitCopy @_eagerMove @owned $View):
+  %1 = alloc_box ${ var @moveOnly View }, var, name "that"
+  %2 = begin_borrow [var_decl] %1
+  %3 = project_box %2, 0
+  %4 = moveonlywrapper_to_copyable_addr %3
+  store %0 to [init] %4
+  %6 = metatype $@thin View.Type
+  %7 = begin_access [read] [static] %3
+  %8 = mark_unresolved_non_copyable_value [no_consume_or_assign] %7
+  %9 = struct_element_addr %8, #View._ptr
+  %10 = load_borrow %9
+  %11 = moveonlywrapper_to_copyable [guaranteed] %10
+  end_borrow %10
+  end_access %7
+  %14 = function_ref @initFn : $@convention(method) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @owned View
+  %15 = apply %14(%11, %6) : $@convention(method) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @owned View
+  %16 = mark_dependence [unresolved] %15 on %2
+  end_borrow %2
+  destroy_value %1
+  return %16
+}
+
+// CHECK-LABEL:  sil [ossa] @testBoxedParamAddr :
+// CHECK-NOT: alloc_box
+// CHECK-LABEL: } // end sil function 'testBoxedParamAddr'
+sil [ossa] @testBoxedParamAddr : $@convention(thin) (@owned View) -> () {
+bb0(%0 : @noImplicitCopy @_eagerMove @owned $View):
+  %1 = alloc_box ${ var @moveOnly View }, var, name "that"
+  %2 = begin_borrow [var_decl] %1
+  %3 = project_box %2, 0
+  %4 = moveonlywrapper_to_copyable_addr %3
+  store %0 to [init] %4
+  %6 = metatype $@thin View.Type
+  %7 = begin_access [read] [static] %3
+  %8 = mark_unresolved_non_copyable_value [no_consume_or_assign] %7
+  %9 = struct_element_addr %8, #View._ptr
+  %10 = load_borrow %9
+  %11 = moveonlywrapper_to_copyable [guaranteed] %10
+  end_borrow %10
+  end_access %7
+  %14 = alloc_stack $View
+  %15 = function_ref @initFnAddr : $@convention(thin) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @out View
+  %16 = apply %15(%14, %11, %6) : $@convention(thin) (UnsafeRawPointer, @thin View.Type) -> @lifetime(borrow 0) @out View
+  mark_dependence_addr [unresolved] %14 on %2
+  dealloc_stack %14
+  end_borrow %2
+  destroy_value %1
+  %99 = tuple ()
+  return %99
+}