[ownership] Require all operands of ref_tail_addr to have guaranteed ownership.

This ensures that the optimizer has a summary of where the ref_tail_addr will no
longer be used. This is important when analyzing the lifetime of the base of the
ref_tail_addr.

I also cleaned up a little the description around the specification for this in
OperandOwnership. Now all instructions that are "INTERIOR_POINTER_PROJECTIONS"
have their own section/macro as a form of self documenting.

Author: gottesmm

lib/SIL/OperandOwnership.cpp

@@ -142,6 +142,18 @@ SHOULD_NEVER_VISIT_INST(StrongRelease)
 #include "swift/AST/ReferenceStorage.def"
 #undef SHOULD_NEVER_VISIT_INST
 
+/// Instructions that are interior pointers into a guaranteed value.
+#define INTERIOR_POINTER_PROJECTION(INST)                                      \
+  OperandOwnershipKindMap OperandOwnershipKindClassifier::visit##INST##Inst(   \
+      INST##Inst *i) {                                                         \
+    assert(i->getNumOperands() && "Expected to have non-zero operands");       \
+    return Map::compatibilityMap(ValueOwnershipKind::Guaranteed,               \
+                                 UseLifetimeConstraint::MustBeLive);           \
+  }
+INTERIOR_POINTER_PROJECTION(RefElementAddr)
+INTERIOR_POINTER_PROJECTION(RefTailAddr)
+#undef INTERIOR_POINTER_PROJECTION
+
 /// Instructions whose arguments are always compatible with one convention.
 #define CONSTANT_OWNERSHIP_INST(OWNERSHIP, USE_LIFETIME_CONSTRAINT, INST)      \
   OperandOwnershipKindMap OperandOwnershipKindClassifier::visit##INST##Inst(   \
@@ -151,7 +163,6 @@ SHOULD_NEVER_VISIT_INST(StrongRelease)
         ValueOwnershipKind::OWNERSHIP,                                         \
         UseLifetimeConstraint::USE_LIFETIME_CONSTRAINT);                       \
   }
-CONSTANT_OWNERSHIP_INST(Guaranteed, MustBeLive, RefElementAddr)
 CONSTANT_OWNERSHIP_INST(Guaranteed, MustBeLive, OpenExistentialValue)
 CONSTANT_OWNERSHIP_INST(Guaranteed, MustBeLive, OpenExistentialBoxValue)
 CONSTANT_OWNERSHIP_INST(Owned, MustBeInvalidated, AutoreleaseValue)
@@ -271,7 +282,6 @@ ACCEPTS_ANY_OWNERSHIP_INST(BridgeObjectToWord)
 ACCEPTS_ANY_OWNERSHIP_INST(ClassifyBridgeObject)
 ACCEPTS_ANY_OWNERSHIP_INST(CopyBlock)
 ACCEPTS_ANY_OWNERSHIP_INST(OpenExistentialBox)
-ACCEPTS_ANY_OWNERSHIP_INST(RefTailAddr)
 ACCEPTS_ANY_OWNERSHIP_INST(RefToRawPointer)
 ACCEPTS_ANY_OWNERSHIP_INST(SetDeallocating)
 ACCEPTS_ANY_OWNERSHIP_INST(ProjectExistentialBox)

lib/SILGen/SILGenBuiltin.cpp

@@ -976,8 +976,8 @@ static ManagedValue emitBuiltinProjectTailElems(SILGenFunction &SGF,
   SILType ElemType = SGF.getLoweredType(subs.getReplacementTypes()[1]->
                                         getCanonicalType()).getObjectType();
 
-  SILValue result = SGF.B.createRefTailAddr(loc, args[0].getValue(),
-                                            ElemType.getAddressType());
+  SILValue result = SGF.B.createRefTailAddr(
+      loc, args[0].borrow(SGF, loc).getValue(), ElemType.getAddressType());
   SILType rawPointerType = SILType::getRawPointerType(SGF.F.getASTContext());
   result = SGF.B.createAddressToPointer(loc, result, rawPointerType);
   return ManagedValue::forUnmanaged(result);

test/SILGen/builtins.swift

@@ -360,6 +360,23 @@ func projectTailElems<T>(h: Header, ty: T.Type) -> Builtin.RawPointer {
 }
 // CHECK: } // end sil function '$s8builtins16projectTailElems1h2tyBpAA6HeaderC_xmtlF'
 
+// Make sure we borrow if this is owned.
+//
+// CHECK-LABEL: sil hidden [ossa] @$s8builtins21projectTailElemsOwned{{[_0-9a-zA-Z]*}}F
+func projectTailElemsOwned<T>(h: __owned Header, ty: T.Type) -> Builtin.RawPointer {
+  // CHECK: bb0([[ARG1:%.*]] : @owned $Header
+  // CHECK:   [[BORROWED_ARG1:%.*]] = begin_borrow [[ARG1]]
+  // CHECK:   [[TA:%.*]] = ref_tail_addr [[BORROWED_ARG1]] : $Header
+  //   -- Once we have passed the address through a2p, we no longer provide any guarantees.
+  //   -- We still need to make sure that the a2p itself is in the borrow site though.
+  // CHECK:   [[A2P:%.*]] = address_to_pointer [[TA]]
+  // CHECK:   end_borrow [[BORROWED_ARG1]]
+  // CHECK:   destroy_value [[ARG1]]
+  // CHECK:   return [[A2P]]
+  return Builtin.projectTailElems(h, ty)
+}
+// CHECK: } // end sil function '$s8builtins21projectTailElemsOwned{{[_0-9a-zA-Z]*}}F'
+
 // CHECK-LABEL: sil hidden [ossa] @$s8builtins11getTailAddr{{[_0-9a-zA-Z]*}}F
 func getTailAddr<T1, T2>(start: Builtin.RawPointer, i: Builtin.Word, ty1: T1.Type, ty2: T2.Type) -> Builtin.RawPointer {
   // CHECK: [[P2A:%.*]] = pointer_to_address %0