[OpaqueValues] Transforms emit addr-only loads.

In opaque values mode, when transforming, load address even when their
type is address-only.

Author: nate-chandler

lib/SILGen/SILGenPoly.cpp

@@ -371,7 +371,7 @@ ManagedValue Transform::transform(ManagedValue v,
   // expect this.
   if (v.getType().isAddress()) {
     auto &inputTL = SGF.getTypeLowering(v.getType());
-    if (!inputTL.isAddressOnly()) {
+    if (!inputTL.isAddressOnly() || !SGF.silConv.useLoweredAddresses()) {
       v = emitManagedLoad(SGF, Loc, v, inputTL);
     }
   }

test/SILGen/Inputs/opaque_values_cxx.h

@@ -0,0 +1,3 @@
+#include <vector>
+
+using VectorOfU32 = std::vector<uint32_t>;

test/SILGen/opaque_values_cxx.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-emit-silgen -enable-sil-opaque-values -Xllvm -sil-full-demangle -cxx-interoperability-mode=swift-5.9 -import-objc-header %S/Inputs/opaque_values_cxx.h -primary-file %s | %FileCheck %s --check-prefix=CHECK
+
+import Cxx
+
+// CHECK-LABEL: sil {{.*}}[ossa] @$sSo3stdO{{(3__1O)?}}0042vectorUInt32allocatorUInt32_mzFHjGjjqraEeaV3Cxx0B8SequenceSCA{{.*}}P13__beginUnsafe11RawIteratorQzyFTW : {{.*}} {
+// CHECK:       bb0([[VECTOR_ADDR:%[^,]+]] :
+// CHECK:         [[VECTOR:%[^,]+]] = load_borrow [[VECTOR_ADDR]]
+// CHECK:         [[BEGIN_FN:%[^,]+]] = function_ref
+// CHECK:         [[BEGIN:%[^,]+]] = apply [[BEGIN_FN]]([[VECTOR]])
+// CHECK:         end_borrow [[VECTOR]]
+// CHECK:         return [[BEGIN]]
+// CHECK-LABEL: } // end sil function '$sSo3stdO{{(3__1O)?}}0042vectorUInt32allocatorUInt32_mzFHjGjjqraEeaV3Cxx0B8SequenceSCA{{.*}}P13__beginUnsafe11RawIteratorQzyFTW'
+func test_cxx_vector_uint32t_iterate(_ n: Int, _ vectorOfU32: VectorOfU32) {
+  for x in vectorOfU32 {}
+}