pretty-print: Fix up ptrdiff handling for %tu, %to, %tx
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Commit Message
Hi!
This is IMHO more of a theoretical case, I believe my current code
doesn't handle %tu or %to or %tx correctly if ptrdiff_t is not one of
int, long int or long long int. For size_t and %zd or %zi I'm
using va_arg (whatever, ssize_t) and hope that ssize_t is the signed
type corresponding to size_t which C99 talks about.
For ptrdiff_t there is no type for unsigned type corresponding to
ptrdiff_t and I'm not aware of a portable way on the host to get
such a type (the fmt tests use hacks like
#define signed /* Type might or might not have explicit 'signed'. */
typedef unsigned __PTRDIFF_TYPE__ unsigned_ptrdiff_t;
#undef signed
but that only works with compilers which predefine __PTRDIFF_TYPE__),
std::make_unsigned<ptrdiff_t> I believe only works reliably if
ptrdiff_t is one of char, signed char, short, int, long or long long,
but won't work e.g. for __int20__ or whatever other weird ptrdiff_t
the host might have.
The following patch assumes host is two's complement (I think we
rely on it pretty much everywhere anyway) and prints unsigned type
corresponding to ptrdiff_t as unsigned long long printing of
ptrdiff_t value masked with 2ULL * PTRDIFF_MAX + 1. So the only
actual limitation is that it doesn't support ptrdiff_t wider than
long long int.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-02-13 Jakub Jelinek <jakub@redhat.com>
* pretty-print.cc (PTRDIFF_MAX): Define if not yet defined.
(pp_integer_with_precision): For unsigned ptrdiff_t printing
with u, o or x print ptrdiff_t argument converted to
unsigned long long and masked with 2ULL * PTRDIFF_MAX + 1.
* error.cc (error_print): For u printing of ptrdiff_t,
print ptrdiff_t argument converted to unsigned long long and
masked with 2ULL * PTRDIFF_MAX + 1.
Jakub
Comments
On 2/13/24 01:21, Jakub Jelinek wrote:
> Hi!
>
> This is IMHO more of a theoretical case, I believe my current code
> doesn't handle %tu or %to or %tx correctly if ptrdiff_t is not one of
> int, long int or long long int. For size_t and %zd or %zi I'm
> using va_arg (whatever, ssize_t) and hope that ssize_t is the signed
> type corresponding to size_t which C99 talks about.
> For ptrdiff_t there is no type for unsigned type corresponding to
> ptrdiff_t and I'm not aware of a portable way on the host to get
> such a type (the fmt tests use hacks like
> #define signed /* Type might or might not have explicit 'signed'. */
> typedef unsigned __PTRDIFF_TYPE__ unsigned_ptrdiff_t;
> #undef signed
> but that only works with compilers which predefine __PTRDIFF_TYPE__),
> std::make_unsigned<ptrdiff_t> I believe only works reliably if
> ptrdiff_t is one of char, signed char, short, int, long or long long,
> but won't work e.g. for __int20__ or whatever other weird ptrdiff_t
> the host might have.
>
> The following patch assumes host is two's complement (I think we
> rely on it pretty much everywhere anyway) and prints unsigned type
> corresponding to ptrdiff_t as unsigned long long printing of
> ptrdiff_t value masked with 2ULL * PTRDIFF_MAX + 1. So the only
> actual limitation is that it doesn't support ptrdiff_t wider than
> long long int.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2024-02-13 Jakub Jelinek <jakub@redhat.com>
>
> * pretty-print.cc (PTRDIFF_MAX): Define if not yet defined.
> (pp_integer_with_precision): For unsigned ptrdiff_t printing
> with u, o or x print ptrdiff_t argument converted to
> unsigned long long and masked with 2ULL * PTRDIFF_MAX + 1.
>
> * error.cc (error_print): For u printing of ptrdiff_t,
> print ptrdiff_t argument converted to unsigned long long and
> masked with 2ULL * PTRDIFF_MAX + 1.
OK
jeff
@@ -752,6 +752,9 @@ output_buffer::~output_buffer ()
obstack_free (&formatted_obstack, NULL);
}
+#ifndef PTRDIFF_MAX
+#define PTRDIFF_MAX INTTYPE_MAXIMUM (ptrdiff_t)
+#endif
/* Format an integer given by va_arg (ARG, type-specifier T) where
type-specifier is a precision modifier as indicated by PREC. F is
@@ -783,7 +786,15 @@ output_buffer::~output_buffer ()
break; \
\
case 4: \
- if (sizeof (ptrdiff_t) <= sizeof (int)) \
+ if (T (-1) >= T (0)) \
+ { \
+ unsigned long long a = va_arg (ARG, ptrdiff_t); \
+ unsigned long long m = PTRDIFF_MAX; \
+ m = 2 * m + 1; \
+ pp_scalar (PP, "%" HOST_LONG_LONG_FORMAT F, \
+ a & m); \
+ } \
+ else if (sizeof (ptrdiff_t) <= sizeof (int)) \
pp_scalar (PP, "%" F, \
(int) va_arg (ARG, ptrdiff_t)); \
else if (sizeof (ptrdiff_t) <= sizeof (long)) \
@@ -886,13 +886,14 @@ error_print (const char *type, const cha
format++;
if (*format == 'u')
{
- ptrdiff_t ptrdiffval = spec[n++].u.ptrdiffval;
- if (sizeof (ptrdiff_t) == sizeof (int))
- error_uinteger ((unsigned) ptrdiffval);
- else if (sizeof (ptrdiff_t) == sizeof (long))
- error_uinteger ((unsigned long) ptrdiffval);
- else
- error_uinteger (ptrdiffval);
+ unsigned long long a = spec[n++].u.ptrdiffval, m;
+#ifdef PTRDIFF_MAX
+ m = PTRDIFF_MAX;
+#else
+ m = INTTYPE_MAXIMUM (ptrdiff_t);
+#endif
+ m = 2 * m + 1;
+ error_uinteger (a & m);
}
else
error_integer (spec[n++].u.ptrdiffval);