Improve XFIXNUM cleanup a bit

Based on Pip Cet’s review (Bug#36370#13).
* src/ccl.c (Fccl_execute_on_string): Use clearer indexing.
* src/dosfns.c (Fint86, Fdos_memput):
Avoid runtime checks for negative fixnums when debugging.
This restores the earlier machine code.
* src/lisp.h (XFIXNUM, XUFIXNUM): Use eassert, not eassume.
(XFIXNAT): At the start, merely eassert FIXNUMP rather
than eassuming FIXNATP.  At the end, eassume that the
result is nonnegative.  This restores help to the compiler
that the previous patch mistakenly removed.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/ccl.c b/src/ccl.c
index f1d4c28df1c..ff42c6f25fc 100644
--- a/src/ccl.c
+++ b/src/ccl.c
@@ -2062,9 +2062,9 @@ usage: (ccl-execute-on-string CCL-PROGRAM STATUS STRING &optional CONTINUE UNIBY
       if (TYPE_RANGED_FIXNUMP (int, AREF (status, i)))
         ccl.reg[i] = XFIXNUM (AREF (status, i));
     }
-  if (FIXNUMP (AREF (status, i)))
+  if (FIXNUMP (AREF (status, 8)))
     {
-      EMACS_INT ic = XFIXNUM (AREF (status, i));
+      EMACS_INT ic = XFIXNUM (AREF (status, 8));
       if (ccl.ic < ic && ic < ccl.size)
         ccl.ic = ic;
     }