[oslog-overlay-fixes] Adopt os_log_pack

Adopt libtrace os_log_pack in order to more accurately provide logging
data to libtrace. This allows the overlay code to supply the caller's pc
to libtrace and fix `log show --source` to show the caller's source
information when called from Swift.

Addresses radar:
<rdar://problem/29195869> os_log in Swift via overlay does not include
'source' filename/line number in `log stream`

Author: mwwa

stdlib/public/SDK/os/os_log.m

@@ -21,23 +21,7 @@
 #include <wchar.h>
 
 #include "os_trace_blob.h"
-
-#ifndef os_fastpath
-#define os_fastpath(x) ((__typeof__(x))OS_EXPECT((long)(x), ~0l))
-#endif
-#ifndef os_slowpath
-#define os_slowpath(x) ((__typeof__(x))OS_EXPECT((long)(x), 0l))
-#endif
-#ifndef os_likely
-#define os_likely(x) OS_EXPECT(!!(x), 1)
-#endif
-#ifndef os_unlikely
-#define os_unlikely(x) OS_EXPECT(!!(x), 0)
-#endif
-
-#ifndef MIN
-#define MIN(a, b)  (((a)<(b))?(a):(b))
-#endif
+#include "thunks.h"
 
 #define OST_FORMAT_MAX_STRING_SIZE 1024
 #define OS_LOG_FMT_MAX_CMDS    48
@@ -92,13 +76,33 @@
     uint8_t cmd_data[];
 } os_log_fmt_cmd_s, *os_log_fmt_cmd_t;
 
-
 typedef struct os_log_fmt_hdr_s {
     os_log_fmt_hdr_flags_t hdr_flags;
     uint8_t hdr_cmd_cnt;
     uint8_t hdr_data[];
 } os_log_fmt_hdr_s, *os_log_fmt_hdr_t;
 
+typedef struct os_log_pack_s {
+    uint64_t        olp_continuous_time;
+    struct timespec olp_wall_time;
+    const void     *olp_mh;
+    const void     *olp_pc;
+    const char     *olp_format;
+    uint8_t         olp_data[0];
+} os_log_pack_s, *os_log_pack_t;
+
+API_AVAILABLE(macosx(10.12.4), ios(10.3), tvos(10.2), watchos(3.2))
+size_t
+_os_log_pack_size(size_t os_log_format_buffer_size);
+
+API_AVAILABLE(macosx(10.12.4), ios(10.3), tvos(10.2), watchos(3.2))
+uint8_t *
+_os_log_pack_fill(os_log_pack_t pack, size_t size, int saved_errno, const void *dso, const char *fmt);
+
+API_AVAILABLE(macosx(10.12.4), ios(10.3), tvos(10.2), watchos(3.2))
+void
+os_log_pack_send(os_log_pack_t pack, os_log_t log, os_log_type_t type);
+
 static inline void
 _os_log_encode_arg(os_trace_blob_t ob, os_log_fmt_cmd_t cmd, const void *data)
 {
@@ -299,17 +303,37 @@
 
 __attribute__((__visibility__("default")))
 void
-_swift_os_log(void *dso, os_log_t oslog, os_log_type_t type, const char *format, va_list args)
+_swift_os_log(void *dso, void *retaddr, os_log_t oslog, os_log_type_t type, const char *format, va_list args)
 {
-  int save_errno = errno; // %m
+  int saved_errno = errno; // %m
   char buf[OS_LOG_FMT_BUF_SIZE];
   os_trace_blob_s ob = {
     .ob_s = buf,
     .ob_size = OS_LOG_FMT_BUF_SIZE,
     .ob_binary = true
   };
 
-  if (_os_log_encode(buf, format, args, save_errno, &ob)) {
-    _os_log_impl(dso, oslog, type, format, (uint8_t *)buf, ob.ob_len);
+  if (_os_log_encode(buf, format, args, saved_errno, &ob)) {
+    // Use os_log_pack_send where available.
+    if (os_log_pack_send) {
+      size_t sz = _os_log_pack_size(ob.ob_len);
+      union { os_log_pack_s pack; uint8_t buf[OS_LOG_FMT_BUF_SIZE + sizeof(os_log_pack_s)]; } u;
+      // _os_log_encode has already packed `saved_errno` into a OSLF_CMD_TYPE_SCALAR command
+      // as the OSLF_CMD_TYPE_ERRNO does not deploy backwards, so passes zero for errno here.
+      uint8_t *ptr = _os_log_pack_fill(&u.pack, sz, 0, dso, format);
+      u.pack.olp_pc = retaddr;
+      memcpy(ptr, buf, ob.ob_len);
+      os_log_pack_send(&u.pack, oslog, type);
+    } else {
+      _os_log_impl(dso, oslog, type, format, (uint8_t *)buf, ob.ob_len);
+    }
   }
 }
+
+__attribute__((__visibility__("default")))
+void *
+_swift_os_log_return_address(void)
+{
+  return __builtin_return_address(1);
+}
+

stdlib/public/SDK/os/os_log.swift

@@ -23,13 +23,14 @@ public func os_log(
   _ args: CVarArg...) 
 {
   guard log.isEnabled(type: type) else { return }
+  let ra = _swift_os_log_return_address()
 
   message.withUTF8Buffer { (buf: UnsafeBufferPointer<UInt8>) in
     // Since dladdr is in libc, it is safe to unsafeBitCast
-                // the cstring argument type.
+    // the cstring argument type.
     let str = unsafeBitCast(buf.baseAddress!, to: UnsafePointer<Int8>.self)
     withVaList(args) { valist in
-      _swift_os_log(dso, log, type, str, valist)
+      _swift_os_log(dso, ra, log, type, str, valist)
     }
   }
 }

stdlib/public/SwiftShims/OSOverlayShims.h

@@ -16,9 +16,11 @@
 #include <os/log.h>
 #include <stdarg.h>
 
-extern void _swift_os_log(const void * _Nullable dso, os_log_t _Nonnull oslog,
-                          os_log_type_t type, const char * _Nonnull format,
-                          va_list args);
+extern const void * _Nullable _swift_os_log_return_address(void);
+
+extern void _swift_os_log(const void * _Nullable dso, const void * _Nullable retaddr,
+                          os_log_t _Nonnull oslog, os_log_type_t type, 
+                          const char * _Nonnull format, va_list args);
 
 static inline os_log_t _Nonnull
 _swift_os_log_default(void) {