Re: DBL_DENORM_MIN should never be 0
On Thu, 11 Sep 2014, Marc Glisse wrote: > On Thu, 11 Sep 2014, Joseph S. Myers wrote: > > > On Thu, 11 Sep 2014, Marc Glisse wrote: > > > > > I don't know what kind of test you have in mind, so I added a runtime > > > test. I > > > am just guessing that it probably fails on alpha because of PR 58757, I > > > can't > > > test. Computing d+d may be even more likely to trigger potential issues, > > > if > > > that's the goal. > > > > Yes, a runtime test. I don't think there should be an xfail without it > > actually having been tested to fail (and then such an xfail should come > > with a comment referencing the bug filed in Bugzilla). > > Would it be ok with the attached testcase then? (same ChangeLog). Yes, OK with that test. -- Joseph S. Myers jos...@codesourcery.com
Re: DBL_DENORM_MIN should never be 0
On Thu, 11 Sep 2014, Joseph S. Myers wrote:
On Thu, 11 Sep 2014, Marc Glisse wrote:
I don't know what kind of test you have in mind, so I added a runtime test. I
am just guessing that it probably fails on alpha because of PR 58757, I can't
test. Computing d+d may be even more likely to trigger potential issues, if
that's the goal.
Yes, a runtime test. I don't think there should be an xfail without it
actually having been tested to fail (and then such an xfail should come
with a comment referencing the bug filed in Bugzilla).
Would it be ok with the attached testcase then? (same ChangeLog).
--
Marc Glisse/* { dg-do run } */
/* { dg-options "-std=c11" } */
/* Test that the smallest positive value is not 0. This needs to be true
even when denormals are not supported, so we do not pass any flag
like -mieee. If it fails on alpha, see PR 58757. */
#include
int main(){
volatile float f = FLT_TRUE_MIN;
volatile double d = DBL_TRUE_MIN;
volatile long double l = LDBL_TRUE_MIN;
if (f == 0 || d == 0 || l == 0)
__builtin_abort ();
return 0;
}
Re: DBL_DENORM_MIN should never be 0
On Thu, 11 Sep 2014, Marc Glisse wrote: > I don't know what kind of test you have in mind, so I added a runtime test. I > am just guessing that it probably fails on alpha because of PR 58757, I can't > test. Computing d+d may be even more likely to trigger potential issues, if > that's the goal. Yes, a runtime test. I don't think there should be an xfail without it actually having been tested to fail (and then such an xfail should come with a comment referencing the bug filed in Bugzilla). -- Joseph S. Myers jos...@codesourcery.com
Re: DBL_DENORM_MIN should never be 0
On Wed, 10 Sep 2014, Joseph S. Myers wrote:
On Wed, 10 Sep 2014, Marc Glisse wrote:
Hello,
according to the C++ standard, numeric_limits::denorm_min should return min
(not 0) when there are no denormals.
Tested with bootstrap+testsuite on x86_64-linux-gnu. I also tested a basic
make all-gcc for vax (only target without denormals apparently) and the macro
did change as expected.
The next step might be to define has_denorm as false in more cases (-mno-ieee
on alpha, -ffast-math on x86, etc) but that's a different issue.
(this is C++ but I believe Joseph is the floating-point expert, hence the cc)
This is a C issue as well (for C11 *_TRUE_MIN).
Ah, indeed. I am updating the comment. And also simplifying float.h. I
could instead do the same #ifdef in C++, but since both users of
__FLT_DENORM_MIN__ want the same thing, it seems better to provide that
directly.
gcc/c-family/
2014-09-10 Marc Glisse
PR target/58757
* c-cppbuiltin.c (builtin_define_float_constants): Correct
__*_DENORM_MIN__ without denormals.
I think there should be some sort of testcase that these values aren't 0.
I don't know what kind of test you have in mind, so I added a runtime
test. I am just guessing that it probably fails on alpha because of PR
58757, I can't test. Computing d+d may be even more likely to trigger
potential issues, if that's the goal.
Passes bootstrap+testsuite on x86_64-linux-gnu.
2014-09-11 Marc Glisse
PR target/58757
gcc/c-family/
* c-cppbuiltin.c (builtin_define_float_constants): Correct
__*_DENORM_MIN__ without denormals.
gcc/
* ginclude/float.h (FLT_TRUE_MIN, DBL_TRUE_MIN, LDBL_TRUE_MIN):
Directly forward to __*_DENORM_MIN__.
gcc/testsuite/
* gcc.dg/c11-true_min-1.c: New testcase.
--
Marc GlisseIndex: gcc/c-family/c-cppbuiltin.c
===
--- gcc/c-family/c-cppbuiltin.c (revision 215134)
+++ gcc/c-family/c-cppbuiltin.c (working copy)
@@ -263,35 +263,28 @@ builtin_define_float_constants (const ch
representable in the given floating point type, b**(1-p). */
sprintf (name, "__%s_EPSILON__", name_prefix);
if (fmt->pnan < fmt->p)
/* This is an IBM extended double format, so 1.0 + any double is
representable precisely. */
sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
else
sprintf (buf, "0x1p%d", 1 - fmt->p);
builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix,
fp_cast);
- /* For C++ std::numeric_limits::denorm_min. The minimum denormalized
- positive floating-point number, b**(emin-p). Zero for formats that
- don't support denormals. */
+ /* For C++ std::numeric_limits::denorm_min and C11 *_TRUE_MIN.
+ The minimum denormalized positive floating-point number, b**(emin-p).
+ The minimum normalized positive floating-point number for formats
+ that don't support denormals. */
sprintf (name, "__%s_DENORM_MIN__", name_prefix);
- if (fmt->has_denorm)
-{
- sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
- builtin_define_with_hex_fp_value (name, type, decimal_dig,
- buf, fp_suffix, fp_cast);
-}
- else
-{
- sprintf (buf, "0.0%s", fp_suffix);
- builtin_define_with_value (name, buf, 0);
-}
+ sprintf (buf, "0x1p%d", fmt->emin - (fmt->has_denorm ? fmt->p : 1));
+ builtin_define_with_hex_fp_value (name, type, decimal_dig,
+ buf, fp_suffix, fp_cast);
sprintf (name, "__%s_HAS_DENORM__", name_prefix);
builtin_define_with_value (name, fmt->has_denorm ? "1" : "0", 0);
/* For C++ std::numeric_limits::has_infinity. */
sprintf (name, "__%s_HAS_INFINITY__", name_prefix);
builtin_define_with_int_value (name,
MODE_HAS_INFINITIES (TYPE_MODE (type)));
/* For C++ std::numeric_limits::has_quiet_NaN. We do not have a
predicate to distinguish a target that has both quiet and
Index: gcc/ginclude/float.h
===
--- gcc/ginclude/float.h(revision 215134)
+++ gcc/ginclude/float.h(working copy)
@@ -171,35 +171,23 @@ see the files COPYING3 and COPYING.RUNTI
#undef DBL_HAS_SUBNORM
#undef LDBL_HAS_SUBNORM
#define FLT_HAS_SUBNORM__FLT_HAS_DENORM__
#define DBL_HAS_SUBNORM__DBL_HAS_DENORM__
#define LDBL_HAS_SUBNORM __LDBL_HAS_DENORM__
/* Minimum positive values, including subnormals. */
#undef FLT_TRUE_MIN
#undef DBL_TRUE_MIN
#undef LDBL_TRUE_MIN
-#if __FLT_HAS_DENORM__
#define FLT_TRUE_MIN __FLT_DENORM_MIN__
-#else
-#define FLT_TRUE_MIN __FLT_MIN__
-#endif
-#if __DBL_HAS_DENORM__
#define DBL_TRUE_MIN __DBL_DENORM_MIN__
-#else
-#define DBL_TRUE_MIN __DBL_MIN__
-#endif
-#if __LDBL_HAS_DENORM__
#define LDBL_TRUE_MIN __LDBL_DENORM_MIN__
-#else
-#define LDBL_TRUE_MIN __LDBL_MIN__
-#endif
#end
Re: DBL_DENORM_MIN should never be 0
On Wed, 10 Sep 2014, Marc Glisse wrote: > Hello, > > according to the C++ standard, numeric_limits::denorm_min should return min > (not 0) when there are no denormals. > > Tested with bootstrap+testsuite on x86_64-linux-gnu. I also tested a basic > make all-gcc for vax (only target without denormals apparently) and the macro > did change as expected. > > The next step might be to define has_denorm as false in more cases (-mno-ieee > on alpha, -ffast-math on x86, etc) but that's a different issue. > > (this is C++ but I believe Joseph is the floating-point expert, hence the cc) This is a C issue as well (for C11 *_TRUE_MIN). > gcc/c-family/ > > 2014-09-10 Marc Glisse > PR target/58757 > * c-cppbuiltin.c (builtin_define_float_constants): Correct > __*_DENORM_MIN__ without denormals. I think there should be some sort of testcase that these values aren't 0. -- Joseph S. Myers jos...@codesourcery.com
DBL_DENORM_MIN should never be 0
Hello,
according to the C++ standard, numeric_limits::denorm_min should return
min (not 0) when there are no denormals.
Tested with bootstrap+testsuite on x86_64-linux-gnu. I also tested a basic
make all-gcc for vax (only target without denormals apparently) and the
macro did change as expected.
The next step might be to define has_denorm as false in more cases
(-mno-ieee on alpha, -ffast-math on x86, etc) but that's a different
issue.
(this is C++ but I believe Joseph is the floating-point expert, hence the
cc)
gcc/c-family/
2014-09-10 Marc Glisse
* c-cppbuiltin.c (builtin_define_float_constants): Correct
__*_DENORM_MIN__ without denormals.
--
Marc GlisseIndex: gcc/c-family/c-cppbuiltin.c
===
--- gcc/c-family/c-cppbuiltin.c (revision 215103)
+++ gcc/c-family/c-cppbuiltin.c (working copy)
@@ -264,34 +264,27 @@ builtin_define_float_constants (const ch
sprintf (name, "__%s_EPSILON__", name_prefix);
if (fmt->pnan < fmt->p)
/* This is an IBM extended double format, so 1.0 + any double is
representable precisely. */
sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
else
sprintf (buf, "0x1p%d", 1 - fmt->p);
builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix,
fp_cast);
/* For C++ std::numeric_limits::denorm_min. The minimum denormalized
- positive floating-point number, b**(emin-p). Zero for formats that
- don't support denormals. */
+ positive floating-point number, b**(emin-p). The minimum normalized
+ positive floating-point number for formats that don't support
+ denormals. */
sprintf (name, "__%s_DENORM_MIN__", name_prefix);
- if (fmt->has_denorm)
-{
- sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
- builtin_define_with_hex_fp_value (name, type, decimal_dig,
- buf, fp_suffix, fp_cast);
-}
- else
-{
- sprintf (buf, "0.0%s", fp_suffix);
- builtin_define_with_value (name, buf, 0);
-}
+ sprintf (buf, "0x1p%d", fmt->emin - (fmt->has_denorm ? fmt->p : 1));
+ builtin_define_with_hex_fp_value (name, type, decimal_dig,
+ buf, fp_suffix, fp_cast);
sprintf (name, "__%s_HAS_DENORM__", name_prefix);
builtin_define_with_value (name, fmt->has_denorm ? "1" : "0", 0);
/* For C++ std::numeric_limits::has_infinity. */
sprintf (name, "__%s_HAS_INFINITY__", name_prefix);
builtin_define_with_int_value (name,
MODE_HAS_INFINITIES (TYPE_MODE (type)));
/* For C++ std::numeric_limits::has_quiet_NaN. We do not have a
predicate to distinguish a target that has both quiet and
