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remove va_arg hacks in printf core with undefined behavior 

the code being removed was written to optimize for size assuming the
compiler cannot collapse code paths for different types with the same
underlying representation. modern compilers sometimes succeed in
making this optimization themselves, but either way it's a small size
difference and not worth the source-level complexity or the UB
involved in this hack.

some incorrect use of va_arg still remains, particularly use of void *
where the actual argument has a different pointer type. fixing this
requires some actual code additions, rather than just removing cruft,
so I'm leaving it to be done later as a separate commit.
This commit is contained in:
Rich Felker 2017-04-22 17:48:37 -04:00
parent e1232f5b51
commit 58e2396a9a
1 changed files with 1 additions and 26 deletions
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27
src/stdio/vfprintf.c
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@ -4,6 +4,7 @@
#include <limits.h>
#include <string.h>
#include <stdarg.h>
#include <stddef.h>
#include <wchar.h>
#include <inttypes.h>
#include <math.h>
@ -26,14 +27,6 @@
#define FLAGMASK (ALT_FORM|ZERO_PAD|LEFT_ADJ|PAD_POS|MARK_POS|GROUPED)
#if UINT_MAX == ULONG_MAX
#define LONG_IS_INT
#endif
#if SIZE_MAX != ULONG_MAX || UINTMAX_MAX != ULLONG_MAX
#define ODD_TYPES
#endif
/* State machine to accept length modifiers + conversion specifiers.
* Result is 0 on failure, or an argument type to pop on success. */
@ -42,23 +35,9 @@ enum {
ZTPRE, JPRE,
STOP,
PTR, INT, UINT, ULLONG,
#ifndef LONG_IS_INT
LONG, ULONG,
#else
#define LONG INT
#define ULONG UINT
#endif
SHORT, USHORT, CHAR, UCHAR,
#ifdef ODD_TYPES
LLONG, SIZET, IMAX, UMAX, PDIFF, UIPTR,
#else
#define LLONG ULLONG
#define SIZET ULONG
#define IMAX LLONG
#define UMAX ULLONG
#define PDIFF LONG
#define UIPTR ULONG
#endif
DBL, LDBL,
NOARG,
MAXSTATE
@ -134,23 +113,19 @@ static void pop_arg(union arg *arg, int type, va_list *ap)
case PTR: arg->p = va_arg(*ap, void *);
break; case INT: arg->i = va_arg(*ap, int);
break; case UINT: arg->i = va_arg(*ap, unsigned int);
#ifndef LONG_IS_INT
break; case LONG: arg->i = va_arg(*ap, long);
break; case ULONG: arg->i = va_arg(*ap, unsigned long);
#endif
break; case ULLONG: arg->i = va_arg(*ap, unsigned long long);
break; case SHORT: arg->i = (short)va_arg(*ap, int);
break; case USHORT: arg->i = (unsigned short)va_arg(*ap, int);
break; case CHAR: arg->i = (signed char)va_arg(*ap, int);
break; case UCHAR: arg->i = (unsigned char)va_arg(*ap, int);
#ifdef ODD_TYPES
break; case LLONG: arg->i = va_arg(*ap, long long);
break; case SIZET: arg->i = va_arg(*ap, size_t);
break; case IMAX: arg->i = va_arg(*ap, intmax_t);
break; case UMAX: arg->i = va_arg(*ap, uintmax_t);
break; case PDIFF: arg->i = va_arg(*ap, ptrdiff_t);
break; case UIPTR: arg->i = (uintptr_t)va_arg(*ap, void *);
#endif
break; case DBL: arg->f = va_arg(*ap, double);
break; case LDBL: arg->f = va_arg(*ap, long double);
}