* Re: printf("%La\n", 1e1000L) crashes with segv.
2021-11-28 7:49 printf("%La\n", 1e1000L) crashes with segv Takashi Yano
@ 2021-11-29 11:01 ` Takashi Yano
2021-11-29 12:26 ` Corinna Vinschen
0 siblings, 1 reply; 3+ messages in thread
From: Takashi Yano @ 2021-11-29 11:01 UTC (permalink / raw)
To: newlib
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On Sun, 28 Nov 2021 16:49:53 +0900
Takashi Yano wrote:
> I noticed that printf("%La\n", 1e1000L) crashes with segv.
> I confirmed this in 32bit cygwin, however, I guess this is
> newlib issue.
>
> Is this the known issue?
I found that the main cause of this issue is lack of frexpl()
function. This is not implemented yet in newlib.
I have made a patch which implements frexpl() to fix this issue.
Please see attachd patch.
--
Takashi Yano <takashi.yano@nifty.ne.jp>
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From 2929df82449dc65eb75350e5d038968698582330 Mon Sep 17 00:00:00 2001
From: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Mon, 29 Nov 2021 19:50:47 +0900
Subject: [PATCH] stdio: Fix issue of printing "%La" format with large exp
part.
- Currently, printf("%La\n", 1e1000L) crashes with segv due to lack
of frexpl() function. With this patch, frexpl() function has been
implemented in libm to solve this issue.
Addresses: https://sourceware.org/pipermail/newlib/2021/018718.html
---
newlib/Makefile.am | 2 +-
newlib/Makefile.in | 3 +-
newlib/libc/include/math.h | 1 +
newlib/libc/stdio/vfprintf.c | 5 +--
newlib/libc/stdio/vfwprintf.c | 5 +--
newlib/libm/common/frexpl.c | 72 ++++++++++++++++++++++++++++++++++-
6 files changed, 77 insertions(+), 11 deletions(-)
diff --git a/newlib/Makefile.am b/newlib/Makefile.am
index d3da43a4b..1235adb8b 100644
--- a/newlib/Makefile.am
+++ b/newlib/Makefile.am
@@ -105,7 +105,7 @@ MATHOBJS_IN_LIBC = \
$(lpfx)s_isnand.$(oext) $(lpfx)sf_isnanf.$(oext) \
$(lpfx)s_nan.$(oext) $(lpfx)sf_nan.$(oext) \
$(lpfx)s_ldexp.$(oext) $(lpfx)sf_ldexp.$(oext) \
- $(lpfx)s_frexp.$(oext) $(lpfx)sf_frexp.$(oext) \
+ $(lpfx)s_frexp.$(oext) $(lpfx)sf_frexp.$(oext) $(lpfx)frexpl.$(oext) \
$(lpfx)s_modf.$(oext) \
$(lpfx)sf_modf.$(oext) $(lpfx)s_scalbn.$(oext) \
$(lpfx)sf_scalbn.$(oext) \
diff --git a/newlib/Makefile.in b/newlib/Makefile.in
index bf15dfea3..68417953d 100644
--- a/newlib/Makefile.in
+++ b/newlib/Makefile.in
@@ -312,6 +312,7 @@ pdfdir = @pdfdir@
prefix = @prefix@
program_transform_name = @program_transform_name@
psdir = @psdir@
+runstatedir = @runstatedir@
sbindir = @sbindir@
shared_machine_dir = @shared_machine_dir@
sharedstatedir = @sharedstatedir@
@@ -415,7 +416,7 @@ MATHOBJS_IN_LIBC = \
$(lpfx)s_isnand.$(oext) $(lpfx)sf_isnanf.$(oext) \
$(lpfx)s_nan.$(oext) $(lpfx)sf_nan.$(oext) \
$(lpfx)s_ldexp.$(oext) $(lpfx)sf_ldexp.$(oext) \
- $(lpfx)s_frexp.$(oext) $(lpfx)sf_frexp.$(oext) \
+ $(lpfx)s_frexp.$(oext) $(lpfx)sf_frexp.$(oext) $(lpfx)frexpl.$(oext) \
$(lpfx)s_modf.$(oext) \
$(lpfx)sf_modf.$(oext) $(lpfx)s_scalbn.$(oext) \
$(lpfx)sf_scalbn.$(oext) \
diff --git a/newlib/libc/include/math.h b/newlib/libc/include/math.h
index 0b6494e6a..799ac494a 100644
--- a/newlib/libc/include/math.h
+++ b/newlib/libc/include/math.h
@@ -509,6 +509,7 @@ extern long double erfcl (long double);
#else /* !_LDBL_EQ_DBL && !__CYGWIN__ */
extern long double hypotl (long double, long double);
extern long double sqrtl (long double);
+extern long double frexpl (long double, int *);
#ifdef __i386__
/* Other long double precision functions. */
extern _LONG_DOUBLE rintl (_LONG_DOUBLE);
diff --git a/newlib/libc/stdio/vfprintf.c b/newlib/libc/stdio/vfprintf.c
index 1aaf05aa4..c1483c0ac 100644
--- a/newlib/libc/stdio/vfprintf.c
+++ b/newlib/libc/stdio/vfprintf.c
@@ -517,10 +517,7 @@ extern int _ldcheck (_LONG_DOUBLE *);
# define _PRINTF_FLOAT_TYPE _LONG_DOUBLE
# define _DTOA_R _ldtoa_r
-/* FIXME - frexpl is not yet supported; and cvt infloops if (double)f
- converts a finite value into infinity. */
-/* # define FREXP frexpl */
-# define FREXP(f,e) ((_LONG_DOUBLE) frexp ((double)f, e))
+# define FREXP frexpl
# endif /* !_NO_LONGDBL */
static char *cvt(struct _reent *, _PRINTF_FLOAT_TYPE, int, int, char *, int *,
diff --git a/newlib/libc/stdio/vfwprintf.c b/newlib/libc/stdio/vfwprintf.c
index 980b31e3b..7384b37d3 100644
--- a/newlib/libc/stdio/vfwprintf.c
+++ b/newlib/libc/stdio/vfwprintf.c
@@ -243,10 +243,7 @@ extern int _ldcheck (_LONG_DOUBLE *);
# define _PRINTF_FLOAT_TYPE _LONG_DOUBLE
# define _DTOA_R _ldtoa_r
-/* FIXME - frexpl is not yet supported; and cvt infloops if (double)f
- converts a finite value into infinity. */
-/* # define FREXP frexpl */
-# define FREXP(f,e) ((_LONG_DOUBLE) frexp ((double)f, e))
+# define FREXP frexpl
# endif /* !_NO_LONGDBL */
static wchar_t *wcvt(struct _reent *, _PRINTF_FLOAT_TYPE, int, int, wchar_t *,
diff --git a/newlib/libm/common/frexpl.c b/newlib/libm/common/frexpl.c
index 79e41fd9e..42ea41062 100644
--- a/newlib/libm/common/frexpl.c
+++ b/newlib/libm/common/frexpl.c
@@ -29,10 +29,11 @@ POSSIBILITY OF SUCH DAMAGE.
*/
#include <math.h>
+#include <float.h>
#include "local.h"
/* On platforms where long double is as wide as double. */
-#ifdef _LDBL_EQ_DBL
+#if defined(_LDBL_EQ_DBL) || (LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024)
long double
frexpl (long double x, int *eptr)
{
@@ -40,3 +41,72 @@ frexpl (long double x, int *eptr)
}
#endif
+#if (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+# if (LDBL_MANT_DIG == 64) /* 80-bit long double */
+union ldbl {
+ long double x;
+ struct {
+# ifdef __IEEE_LITTLE_ENDIAN /* for Intel CPU */
+ __uint32_t fracl;
+ __uint32_t frach;
+ __uint32_t sexp:16;
+ __uint32_t pad:16;
+# endif
+# ifdef __IEEE_BIG_ENDIAN /* for m86k */
+ __uint32_t sexp:16;
+ __uint32_t pad:16
+ __uint32_t frach;
+ __uint32_t fracl;
+# endif
+ } u32;
+};
+# else /* LDBL_MANT_DIG == 113, 128-bit long double */
+union ldbl {
+ long double x;
+ struct {
+# ifdef __IEEE_LITTLE_ENDIAN
+ __uint32_t fracl;
+ __uint32_t fraclm;
+ __uint32_t frachm;
+ __uint32_t frach:16;
+ __uint32_t sexp:16;
+# endif
+# ifdef __IEEE_BIG_ENDIAN
+#ifndef ___IEEE_BYTES_LITTLE_ENDIAN
+ __uint32_t sexp:16;
+ __uint32_t frach:16;
+#else /* ARMEL without __VFP_FP__ */
+ __uint32_t frach:16;
+ __uint32_t sexp:16;
+#endif
+ __uint32_t frachm;
+ __uint32_t fraclm;
+ __uint32_t fracl;
+# endif
+ } u32;
+};
+# endif
+
+static const double two114 = 0x1p114;
+
+long double
+frexpl (long double x, int *eptr)
+{
+ union ldbl u;
+ u.x = x;
+ int e = u.u32.sexp & 0x7fff;
+ *eptr = 0;
+ if (e == 0x7fff || x == 0)
+ return x; /* 0,inf,nan */
+ if (e == 0)
+ {
+ x *= two114;
+ u.x = x;
+ e = u.u32.sexp & 0x7fff;
+ *eptr -= 114;
+ }
+ *eptr += e - 16382;
+ u.u32.sexp = (u.u32.sexp & 0x8000) | 0x3ffe;
+ return u.x;
+}
+#endif /* End of 80-bit or 128-bit long double */
--
2.33.0
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