From 0c80cb39af7a0f6b0ad73d38bf28a8fc1f50b3c7 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Mon, 19 Aug 2019 15:50:02 +1000
Subject: [PATCH] py: Introduce MP_UNREACHABLE macro to annotate unreachable
 code.

And use it to replace the same pattern at the end of nlrthumb.c:nlr_jump.
---
 py/mpconfig.h | 9 +++++++++
 py/nlrthumb.c | 6 +-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/py/mpconfig.h b/py/mpconfig.h
index a21a6c707..e8f60bd77 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1527,6 +1527,15 @@ typedef double mp_float_t;
 #define MP_UNLIKELY(x) __builtin_expect((x), 0)
 #endif
 
+// To annotate that code is unreachable
+#ifndef MP_UNREACHABLE
+#if defined(__GNUC__)
+#define MP_UNREACHABLE __builtin_unreachable();
+#else
+#define MP_UNREACHABLE for (;;);
+#endif
+#endif
+
 #ifndef MP_HTOBE16
 #if MP_ENDIANNESS_LITTLE
 # define MP_HTOBE16(x) ((uint16_t)( (((x) & 0xff) << 8) | (((x) >> 8) & 0xff) ))
diff --git a/py/nlrthumb.c b/py/nlrthumb.c
index eef05229d..bc3038827 100644
--- a/py/nlrthumb.c
+++ b/py/nlrthumb.c
@@ -135,11 +135,7 @@ NORETURN void nlr_jump(void *val) {
     :                               // clobbered registers
     );
 
-    #if defined(__GNUC__)
-    __builtin_unreachable();
-    #else
-    for (;;); // needed to silence compiler warning
-    #endif
+    MP_UNREACHABLE
 }
 
 #endif // MICROPY_NLR_THUMB