From f0b0105d913a94c66f230874c9269b19dbbc83bd Mon Sep 17 00:00:00 2001
From: Paul Eggert
Date: Tue, 19 May 2020 23:22:40 -0700
Subject: Hoist some byte-code checking out of eval

Check Lisp_Compiled objects better as they’re created,
so that the byte-code interpreter needn’t do the checks
each time it executes them.  This improved performance
of ‘make compile-always’ by 1.5% on my platform.  Also,
improve the quality of the (still-incomplete) checks, as
this is more practical now that they’re done less often.
* src/alloc.c (make_byte_code): Remove.  All uses removed.
(Fmake_byte_code): Put a better (though still incomplete)
check here instead.  Simplify by using Fvector instead
of make_uninit_vector followed by memcpy, and by using
XSETPVECTYPE instead of make_byte_code followed by XSETCOMPILED.
* src/bytecode.c (Fbyte_code): Do sanity check and conditional
translation to unibyte here instead of each time the function is
executed.
(exec_byte_code): Omit no-longer-necessary sanity and
unibyte checking.  Use SCHARS instead of SBYTES where
either will do, as SCHARS is faster.
* src/eval.c (fetch_and_exec_byte_code): New function.
(funcall_lambda): Use it.
(funcall_lambda, lambda_arity, Ffetch_bytecode):
Omit no-longer-necessary sanity checks.
(Ffetch_bytecode): Add sanity check if actually fetching.
* src/lisp.h (XSETCOMPILED): Remove.  All uses removed.
* src/lread.c (read1): Check byte-code objects more thoroughly,
albeit still incompletely, and do translation to unibyte here
instead of each time the function is executed.
(read1): Use XSETPVECYPE instead of make_byte_code.
(read_vector): Omit no-longer-necessary sanity check.
---
 src/bytecode.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

(limited to 'src/bytecode.c')

diff --git a/src/bytecode.c b/src/bytecode.c
index 3c90544f3f2..5ac30aa1010 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -319,6 +319,19 @@ the third, MAXDEPTH, the maximum stack depth used in this function.
 If the third argument is incorrect, Emacs may crash.  */)
   (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth)
 {
+  if (! (STRINGP (bytestr) && VECTORP (vector) && FIXNATP (maxdepth)))
+    error ("Invalid byte-code");
+
+  if (STRING_MULTIBYTE (bytestr))
+    {
+      /* BYTESTR must have been produced by Emacs 20.2 or earlier
+	 because it produced a raw 8-bit string for byte-code and now
+	 such a byte-code string is loaded as multibyte with raw 8-bit
+	 characters converted to multibyte form.  Convert them back to
+	 the original unibyte form.  */
+      bytestr = Fstring_as_unibyte (bytestr);
+    }
+
   return exec_byte_code (bytestr, vector, maxdepth, Qnil, 0, NULL);
 }
 
@@ -344,21 +357,10 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   int volatile this_op = 0;
 #endif
 
-  CHECK_STRING (bytestr);
-  CHECK_VECTOR (vector);
-  CHECK_FIXNAT (maxdepth);
+  eassert (!STRING_MULTIBYTE (bytestr));
 
   ptrdiff_t const_length = ASIZE (vector);
-
-  if (STRING_MULTIBYTE (bytestr))
-    /* BYTESTR 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 originally intended unibyte form.  */
-    bytestr = Fstring_as_unibyte (bytestr);
-
-  ptrdiff_t bytestr_length = SBYTES (bytestr);
+  ptrdiff_t bytestr_length = SCHARS (bytestr);
   Lisp_Object *vectorp = XVECTOR (vector)->contents;
 
   unsigned char quitcounter = 1;
-- 
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