LifetimeDependentInsertion: assert on non-inout parameter dependency

The will be supported in a future commit that adds mark_dependence_addr.

Author: atrick

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceInsertion.swift

@@ -272,6 +272,9 @@ private func insertParameterDependencies(apply: LifetimeDependentApply, target:
 
   sources.initializeBases(context)
 
+  assert(target.value.type.isAddress,
+         "lifetime-dependent parameter must be 'inout'")
+
   Builder.insert(after: apply.applySite, context) {
     insertMarkDependencies(value: target.value, initializer: nil, bases: sources.bases, builder: $0, context)
   }
@@ -285,14 +288,14 @@ private func insertMarkDependencies(value: Value, initializer: Instruction?,
     let markDep = builder.createMarkDependence(
       value: currentValue, base: base, kind: .Unresolved)
 
-    // Address dependencies cannot be represented as SSA values, so it does not make sense to replace any uses of the
-    // dependent address.
-    //
-    // TODO: either (1) insert a separate mark_dependence_addr instruction with no return value, or (2) perform data
-    // flow to replace all reachable address uses, and if any aren't dominated by base, then insert an extra
-    // escaping mark_dependence at this apply site that directly uses the mark_dependence [nonescaping] to force
-    // diagnostics to fail.
-    if !value.type.isAddress {
+    if value.type.isAddress {
+      // Address dependencies cannot be represented as SSA values, so it does not make sense to replace any uses of the
+      // dependent address.
+      //
+      // TODO: insert a separate mark_dependence_addr instruction with no return value and do not update currentValue.
+    } else {
+      // TODO: implement non-inout parameter dependencies. This assumes that currentValue is the apply immediately
+      // preceeding the mark_dependence.
       let uses = currentValue.uses.lazy.filter {
         if $0.isScopeEndingUse {
           return false

test/SILOptimizer/lifetime_dependence/semantics.swift

@@ -600,3 +600,12 @@ func testBorrowedAddressableIntReturn(arg: Holder) -> Span<Int> {
 } // todo-note  {{this use causes the lifetime-dependent value to escape}}
 
 */
+
+
+// =============================================================================
+// Parameter dependencies
+// =============================================================================
+
+// rdar://146401190 ([nonescapable] implement non-inout parameter dependencies)
+@lifetime(span: borrow holder)
+func testParameterDep(holder: Holder, span: Span<Int>) {}  // expected-error {{lifetime-dependent parameter must be 'inout'}}