[ownership-value] When passing in a class to materializeForSet, use a store_borrow, rather than a store [init].

The reason why this needs to be done is that we represent class pointers as
guaranteed, but we need to pass them as inout, violating the guaranteed
assumption. The truth is, we should be passing them in guaranteed but due to the
large required AST changes needed, we do not today.

Since we model this as an inout today, SILGen rightfully tries to use a store
[init] which is consuming. This commit works around that issue by using a
store_guaranteed.

rdar://29791263

Author: gottesmm

lib/SILGen/SILGenLValue.cpp

@@ -913,8 +913,12 @@ namespace {
                                             baseFormalType);
 
             baseAddress = gen.emitTemporaryAllocation(loc, base.getType());
-            gen.B.emitStoreValueOperation(loc, base.getValue(), baseAddress,
-                                          StoreOwnershipQualifier::Init);
+            if (base.getOwnershipKind() == ValueOwnershipKind::Guaranteed) {
+              gen.B.createStoreBorrow(loc, base.getValue(), baseAddress);
+            } else {
+              gen.B.emitStoreValueOperation(loc, base.getValue(), baseAddress,
+                                            StoreOwnershipQualifier::Init);
+            }
           }
           baseMetatype = gen.B.createMetatype(loc, metatypeType);
 

test/SILGen/accessors.swift

@@ -68,7 +68,7 @@ func test0(_ ref: A) {
 // CHECK-NEXT: [[CALLBACK:%.*]] = pointer_to_thin_function [[CALLBACK_ADDR]] : $Builtin.RawPointer to $@convention(method) (Builtin.RawPointer, @inout Builtin.UnsafeValueBuffer, @inout A, @thick A.Type) -> ()
 // CHECK-NEXT: [[TEMP2:%.*]] = alloc_stack $A
 // SEMANTIC SIL TODO: This is an issue caused by the callback for materializeForSet in the class case taking the value as @inout when it should really take it as @guaranteed.
-// CHECK-NEXT: store [[BORROWED_ARG_LHS]] to [init] [[TEMP2]] : $*A
+// CHECK-NEXT: store_borrow [[BORROWED_ARG_LHS]] to [[TEMP2]] : $*A
 // CHECK-NEXT: [[T0:%.*]] = metatype $@thick A.Type
 // CHECK-NEXT: [[T1:%.*]] = address_to_pointer [[ADDR]] : $*OrdinarySub to $Builtin.RawPointer
 // CHECK-NEXT: apply [[CALLBACK]]([[T1]], [[STORAGE]], [[TEMP2]], [[T0]])
@@ -130,7 +130,7 @@ func test1(_ ref: B) {
 // CHECK:    [[WRITEBACK]]([[CALLBACK_ADDR:%.*]] : $Builtin.RawPointer):
 // CHECK-NEXT: [[CALLBACK:%.*]] = pointer_to_thin_function [[CALLBACK_ADDR]] : $Builtin.RawPointer to $@convention(method) (Builtin.RawPointer, @inout Builtin.UnsafeValueBuffer, @inout B, @thick B.Type) -> ()
 // CHECK-NEXT: [[TEMP2:%.*]] = alloc_stack $B
-// CHECK-NEXT: store [[BORROWED_ARG_RHS]] to [init] [[TEMP2]] : $*B
+// CHECK-NEXT: store_borrow [[BORROWED_ARG_RHS]] to [[TEMP2]] : $*B
 // CHECK-NEXT: [[T0:%.*]] = metatype $@thick B.Type
 // CHECK-NEXT: [[T1:%.*]] = address_to_pointer [[ADDR]] : $*MutatingSub to $Builtin.RawPointer
 // CHECK-NEXT: apply [[CALLBACK]]([[T1]], [[STORAGE]], [[TEMP2]], [[T0]])
@@ -156,7 +156,7 @@ func test1(_ ref: B) {
 // CHECK:    [[WRITEBACK]]([[CALLBACK_ADDR:%.*]] : $Builtin.RawPointer):
 // CHECK-NEXT: [[CALLBACK:%.*]] = pointer_to_thin_function [[CALLBACK_ADDR]] : $Builtin.RawPointer to $@convention(method) (Builtin.RawPointer, @inout Builtin.UnsafeValueBuffer, @inout B, @thick B.Type) -> ()
 // CHECK-NEXT: [[TEMP2:%.*]] = alloc_stack $B
-// CHECK-NEXT: store [[BORROWED_ARG_LHS]] to [init] [[TEMP2]] : $*B
+// CHECK-NEXT: store_borrow [[BORROWED_ARG_LHS]] to [[TEMP2]] : $*B
 // CHECK-NEXT: [[T0:%.*]] = metatype $@thick B.Type
 // CHECK-NEXT: [[T1:%.*]] = address_to_pointer [[ADDR]] : $*MutatingSub to $Builtin.RawPointer
 // CHECK-NEXT: apply [[CALLBACK]]([[T1]], [[STORAGE2]], [[TEMP2]], [[T0]])