From 3017f87fbd0461b9460e7261a095fc86e166b30e Mon Sep 17 00:00:00 2001
From: Stefan Monnier
Date: Mon, 11 Jun 2012 11:13:27 -0400
Subject: Don't purify in Fmake_byte_code. * src/alloc.c (make_byte_code): New
 function. (Fmake_byte_code): Use it.  Don't purify here. * src/lread.c
 (read1): Use it as well to avoid extra allocation.

---
 src/alloc.c | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

(limited to 'src/alloc.c')

diff --git a/src/alloc.c b/src/alloc.c
index da2b7ac4330..7051af9b99c 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3401,6 +3401,19 @@ usage: (vector &rest OBJECTS)  */)
   return val;
 }
 
+void
+make_byte_code (struct Lisp_Vector *v)
+{
+  if (v->header.size > 1 && STRINGP (v->contents[1])
+      && STRING_MULTIBYTE (v->contents[1]))
+    /* BYTECODE-STRING must have been produced by Emacs 20.2 or the
+       earlier because they produced a raw 8-bit string for byte-code
+       and now such a byte-code string is loaded as multibyte while
+       raw 8-bit characters converted to multibyte form.  Thus, now we
+       must convert them back to the original unibyte form.  */
+    v->contents[1] = Fstring_as_unibyte (v->contents[1]);
+  XSETPVECTYPE (v, PVEC_COMPILED);
+}
 
 DEFUN ("make-byte-code", Fmake_byte_code, Smake_byte_code, 4, MANY, 0,
        doc: /* Create a byte-code object with specified arguments as elements.
@@ -3424,28 +3437,21 @@ usage: (make-byte-code ARGLIST BYTE-CODE CONSTANTS DEPTH &optional DOCSTRING INT
   ptrdiff_t i;
   register struct Lisp_Vector *p;
 
-  XSETFASTINT (len, nargs);
-  if (!NILP (Vpurify_flag))
-    val = make_pure_vector (nargs);
-  else
-    val = Fmake_vector (len, Qnil);
+  /* We used to purecopy everything here, if purify-flga was set.  This worked
+     OK for Emacs-23, but with Emacs-24's lexical binding code, it can be
+     dangerous, since make-byte-code is used during execution to build
+     closures, so any closure built during the preload phase would end up
+     copied into pure space, including its free variables, which is sometimes
+     just wasteful and other times plainly wrong (e.g. those free vars may want
+     to be setcar'd).  */
 
-  if (nargs > 1 && STRINGP (args[1]) && STRING_MULTIBYTE (args[1]))
-    /* BYTECODE-STRING must have been produced by Emacs 20.2 or the
-       earlier because they produced a raw 8-bit string for byte-code
-       and now such a byte-code string is loaded as multibyte while
-       raw 8-bit characters converted to multibyte form.  Thus, now we
-       must convert them back to the original unibyte form.  */
-    args[1] = Fstring_as_unibyte (args[1]);
+  XSETFASTINT (len, nargs);
+  val = Fmake_vector (len, Qnil);
 
   p = XVECTOR (val);
   for (i = 0; i < nargs; i++)
-    {
-      if (!NILP (Vpurify_flag))
-	args[i] = Fpurecopy (args[i]);
-      p->contents[i] = args[i];
-    }
-  XSETPVECTYPE (p, PVEC_COMPILED);
+    p->contents[i] = args[i];
+  make_byte_code (p);
   XSETCOMPILED (val, p);
   return val;
 }
@@ -3470,7 +3476,7 @@ union aligned_Lisp_Symbol
 
 /* Each symbol_block is just under 1020 bytes long, since malloc
    really allocates in units of powers of two and uses 4 bytes for its
-   own overhead. */
+   own overhead.  */
 
 #define SYMBOL_BLOCK_SIZE \
   ((1020 - sizeof (struct symbol_block *)) / sizeof (union aligned_Lisp_Symbol))
-- 
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