[Runtime] Tidy up section declarations slightly.

This also calls out the reflection sections, even though we don't
actually need to do anything special for them (as it turns out).

rdar://123504095

Author: al45tair

stdlib/public/runtime/SwiftRT-ELF-WASM.cpp

@@ -36,32 +36,43 @@ static const void *__backtraceRef __attribute__((used))
 // by the linker.  Otherwise, we may end up with undefined symbol references as
 // the linker table section was never constructed.
 #if defined(__ELF__)
-# define DECLARE_EMPTY_METADATA_SECTION(name) __asm__("\t.section " #name ",\"a\"\n");
+# define DECLARE_EMPTY_METADATA_SECTION(name,attrs) __asm__("\t.section " #name ",\"" attrs "\"\n");
 #elif defined(__wasm__)
-# define DECLARE_EMPTY_METADATA_SECTION(name) __asm__("\t.section " #name ",\"R\",@\n");
+# define DECLARE_EMPTY_METADATA_SECTION(name,attrs) __asm__("\t.section " #name ",\"R\",@\n");
 #endif
 
-#define DECLARE_SWIFT_SECTION(name)                                                          \
-  DECLARE_EMPTY_METADATA_SECTION(name)                                                                \
-  __attribute__((__visibility__("hidden"),__aligned__(1))) extern const char __start_##name; \
-  __attribute__((__visibility__("hidden"),__aligned__(1))) extern const char __stop_##name;
+#define BOUNDS_VISIBILITY __attribute__((__visibility__("hidden"),__aligned__(1)))
+#define DECLARE_BOUNDS(name)                            \
+  BOUNDS_VISIBILITY extern const char __start_##name;   \
+  BOUNDS_VISIBILITY extern const char __stop_##name;
+
+#define DECLARE_SWIFT_SECTION(name)             \
+  DECLARE_EMPTY_METADATA_SECTION(name,"aR")     \
+  DECLARE_BOUNDS(name)
+
+// These may or may not be present, depending on compiler switches; it's
+// worth calling them out as a result.
+#define DECLARE_SWIFT_REFLECTION_SECTION(name)  \
+  DECLARE_SWIFT_SECTION(name)
 
 extern "C" {
 DECLARE_SWIFT_SECTION(swift5_protocols)
 DECLARE_SWIFT_SECTION(swift5_protocol_conformances)
 DECLARE_SWIFT_SECTION(swift5_type_metadata)
 
-DECLARE_SWIFT_SECTION(swift5_typeref)
-DECLARE_SWIFT_SECTION(swift5_reflstr)
-DECLARE_SWIFT_SECTION(swift5_fieldmd)
-DECLARE_SWIFT_SECTION(swift5_assocty)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_fieldmd)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_builtin)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_assocty)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_capture)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_reflstr)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_typeref)
+DECLARE_SWIFT_REFLECTION_SECTION(swift5_mpenum)
+
 DECLARE_SWIFT_SECTION(swift5_replace)
 DECLARE_SWIFT_SECTION(swift5_replac2)
-DECLARE_SWIFT_SECTION(swift5_builtin)
-DECLARE_SWIFT_SECTION(swift5_capture)
-DECLARE_SWIFT_SECTION(swift5_mpenum)
 DECLARE_SWIFT_SECTION(swift5_accessible_functions)
 DECLARE_SWIFT_SECTION(swift5_runtime_attributes)
+
 DECLARE_SWIFT_SECTION(swift5_tests)
 }