From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 5 Feb 2016 22:37:09 +0000 (-0800)
Subject: Omit XLI (init) == 0 optimization in make-vector
X-Git-Tag: emacs-26.0.90~2727
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=130056880fe9d807fbaee5bc5f68249ea9cf6438;p=emacs.git

Omit XLI (init) == 0 optimization in make-vector

* src/alloc.c (Fmake_vector): Simplify by omitting the (XLI (init)
== 0) case, as this optimization is probably not worth the hassle.
Just for the record, the test for that case could have been
(XLI (init) % ((EMACS_UINT) -1 / UCHAR_MAX) == 0) (!),
assuming the typical platform with no padding bits and where
conversion to int omits the most significant bits.
---

diff --git a/src/alloc.c b/src/alloc.c
index 031c78c07ca..92945bc8afc 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3321,14 +3321,9 @@ See also the function `vector'.  */)
   (Lisp_Object length, Lisp_Object init)
 {
   CHECK_NATNUM (length);
-
   struct Lisp_Vector *p = allocate_vector (XFASTINT (length));
-  if (XLI (init) == 0)
-    memset (p->contents, 0, XFASTINT (length) * sizeof p->contents[0]);
-  else
-    for (ptrdiff_t i = 0; i < XFASTINT (length); i++)
-      p->contents[i] = init;
-
+  for (ptrdiff_t i = 0; i < XFASTINT (length); i++)
+    p->contents[i] = init;
   return make_lisp_ptr (p, Lisp_Vectorlike);
 }