Re: printf size requirement

[Eric Blake <ebb9 at byu dot net>]

Joel Sherrill <joel.sherrill <at> oarcorp.com> writes:

> >> + wide character support is in both and is about .75K

It looks like vfprintf.c tries to minimize wide character support if configured 
with --disable-newlib-mb, as evidenced by the use of _MB_CAPABLE.  
Unfortunately, there are uses of _wcrtomb_r outside of _MB_CAPABLE blocks, 
meaning that this was a half-baked disable.  Jeff, is it okay to apply this 
patch, since the POSIX-mandated '%C', '%lc', '%S', and '%ls' are already 
crippled in non-multibyte builds, in an effort to reduce code size there?

patch1:
2007-04-24  Eric Blake  <ebb9@byu.net>

	* libc/stdio/vfprintf.c (_VFPRINTF_R): Avoid multibyte when not
	_MB_CAPABLE.

Meanwhile, we could intentionally cripple the iprintf variants to not support 
wide characters, in order to continue keeping iprintf lightweight.  OK to apply 
this patch on top of the previous?

patch2:
2007-04-24  Eric Blake  <ebb9@byu.net>

	* libc/stdio/vfprintf.c [INTEGER_ONLY]: Always avoid multibyte in
	iprintf.


> >> + printf version includes the "mprec" code, references
> >>     
> >   soft float, etc.

If I understand correctly, there is a configure-time decision as to whether 
your platform defaults to hard or soft float; but yes, pulling in floating 
point code is part of the printf bloat.

> >> + both include locale code

printf currently needs locale in order to support the locale decimal 
character.  But it seems like iprintf should not be sucking it in; I'm not 
seeing where that is happening, since the only call to localeconf is protected 
by FLOATING_POINT.

This also points out another printf bug: localeconv() is not threadsafe, but 
POSIX requires printf to be threadsafe, so using localeconv()->decimal_point 
probably violates POSIX.  It certainly isn't reentrant, at any rate.  And if 
newlib is truly hard-coded to the C locale, even this isn't necessary - we 
could just use '.' and be done with it.

> >   --enable-newlib-io-pos-args enable printf-family positional arg support
> >   
> I see the code that this disables but can't tell if this is disabling 
> something OpenGroup
> or POSIX expect to be present.

C99 does not require it, but POSIX does.  It is what makes
printf("%2$*1$d",width,value) work.  If all you care about is C99, then turn it 
off, but unfortunately, it isn't the biggest source of bloat.

> >   --enable-newlib-mb        enable multibyte support
> >   
> This looks like a feature which might be worth discussing disabling or 
> possibly
> adding as a multilib variant.  But it would double the number of 
> libc.a's we ship
> and with 11 targets and 70 libc.a's already, it doesn't sound appealing.

If patch2 is applied, you will get lightweight iprintf without multilib.  But 
if you do go with multilib, then even patch1 should help reduce size of the non-
multibyte variant.

-- 
Eric Blake

patch1:
Index: libc/stdio/vfprintf.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/vfprintf.c,v
retrieving revision 1.51
diff -u -r1.51 vfprintf.c
--- libc/stdio/vfprintf.c	24 Apr 2007 16:01:15 -0000	1.51
+++ libc/stdio/vfprintf.c	24 Apr 2007 16:38:23 -0000
@@ -821,6 +821,7 @@
 		case 'c':
 		case 'C':
 			cp = buf;
+#ifdef _MB_CAPABLE
 			if (ch == 'C' || (flags & LONGINT)) {
 				mbstate_t ps;
 
@@ -832,7 +833,9 @@
 					goto error; 
 				}
 			}
-			else {
+			else
+#endif /* _MB_CAPABLE */
+                        {
 				*cp = GET_ARG (N, ap, int);
 				size = 1;
 			}
@@ -1010,6 +1013,7 @@
 				cp = "(null)";
 				size = 6;
 			}
+#ifdef _MB_CAPABLE
 			else if (ch == 'S' || (flags & LONGINT)) {
 				mbstate_t ps;
 				_CONST wchar_t *wcp;
@@ -1066,6 +1070,7 @@
 				cp = malloc_buf;
 				cp[size] = '\0';
 			}
+#endif /* _MB_CAPABLE */
 			else if (prec >= 0) {
 				/*
 				 * can't use strlen; can only look for the



patch2:
Index: libc/stdio/vfprintf.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/vfprintf.c,v
retrieving revision 1.51
diff -u -r1.51 vfprintf.c
--- libc/stdio/vfprintf.c	24 Apr 2007 16:01:15 -0000	1.51
+++ libc/stdio/vfprintf.c	24 Apr 2007 16:30:26 -0000
@@ -161,14 +161,15 @@
 #include <newlib.h>
 
 #ifdef INTEGER_ONLY
-#define VFPRINTF vfiprintf
-#define _VFPRINTF_R _vfiprintf_r
+# define VFPRINTF vfiprintf
+# define _VFPRINTF_R _vfiprintf_r
+# undef _MB_CAPABLE
 #else
-#define VFPRINTF vfprintf
-#define _VFPRINTF_R _vfprintf_r
-#ifndef NO_FLOATING_POINT
-#define FLOATING_POINT
-#endif
+# define VFPRINTF vfprintf
+# define _VFPRINTF_R _vfprintf_r
+# ifndef NO_FLOATING_POINT
+#  define FLOATING_POINT
+# endif
 #endif
 
 #define _NO_POS_ARGS