Fix crash due to non-contiguous EMACS_INT (Bug#10780).

* lisp.h (VALBITS): Move definition up, so that USE_LSB_TAG can use it.
(USE_LSB_TAG): Do not define if UINTPTR_MAX >> VALBITS == 0.
It's useless in that case, and it can cause problems on hosts
that allocate halves of EMACS_INT values separately.
Reported by Dan Horák.  Diagnosed by Andreas Schwab in
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10780#30>.
* mem-limits.h (EXCEEDS_LISP_PTR): Define to 0 on hosts where
UINTPTR_MAX >> VALBITS == 0.  This is required by the above change;
it avoids undefined behavior on hosts where shifting right by more
than the word width has undefined behavior.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/mem-limits.h b/src/mem-limits.h
index 472e591b38d..244592a9768 100644
--- a/src/mem-limits.h
+++ b/src/mem-limits.h
@@ -34,7 +34,7 @@ extern int etext;
 #endif
 
 extern char *start_of_data (void);
-#if defined USE_LSB_TAG
+#if defined USE_LSB_TAG || UINTPTR_MAX >> VALBITS == 0
 #define EXCEEDS_LISP_PTR(ptr) 0
 #elif defined DATA_SEG_BITS
 #define EXCEEDS_LISP_PTR(ptr) \