Skip to content

Commit 42f8eee

Browse files
dexonsmithdexonsmith
committedApr 21, 2017
cmath: Skip Libc for integral types in isinf, etc.
For std::isinf, the standard requires effectively calling isinf as double from Libc for integral types. But integral types are never infinite; we don't need to call Libc to return false. Also short-circuit other functions where Libc won't have interesting answers: signbit, fpclassify, isfinite, isnan, and isnormal. I added correctness tests for integral types since we're no longer deferring to Libc. In review it was pointed out that in future revisions of the C++ standard we may add more types to std::is_arithmetic (e.g., std::is_fixed_point). I'll leave it to a future commit to hack this to allow using math functions on those. We'll need to change things like __libcpp_fpclassify anyway, so I'm not sure anything here would really be future-proof. https://reviews.llvm.org/D31561 rdar://problem/31361223 llvm-svn: 301060
·
llvmorg-21-initllvmorg-5.0.0-rc1
1 parent e1bd7cc commit 42f8eee

File tree

2 files changed

+114
-8
lines changed

2 files changed

+114
-8
lines changed
 

‎libcxx/include/math.h

+81-8
Original file line numberDiff line numberDiff line change
@@ -307,6 +307,7 @@ long double truncl(long double x);
307307
extern "C++" {
308308

309309
#include <type_traits>
310+
#include <limits>
310311

311312
// signbit
312313

@@ -324,22 +325,50 @@ __libcpp_signbit(_A1 __lcpp_x) _NOEXCEPT
324325

325326
template <class _A1>
326327
inline _LIBCPP_INLINE_VISIBILITY
327-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
328+
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
328329
signbit(_A1 __lcpp_x) _NOEXCEPT
329330
{
330331
return __libcpp_signbit((typename std::__promote<_A1>::type)__lcpp_x);
331332
}
332333

334+
template <class _A1>
335+
inline _LIBCPP_INLINE_VISIBILITY
336+
typename std::enable_if<
337+
std::is_integral<_A1>::value && std::is_signed<_A1>::value, bool>::type
338+
signbit(_A1 __lcpp_x) _NOEXCEPT
339+
{ return __lcpp_x < 0; }
340+
341+
template <class _A1>
342+
inline _LIBCPP_INLINE_VISIBILITY
343+
typename std::enable_if<
344+
std::is_integral<_A1>::value && !std::is_signed<_A1>::value, bool>::type
345+
signbit(_A1) _NOEXCEPT
346+
{ return false; }
347+
333348
#elif defined(_LIBCPP_MSVCRT)
334349

335350
template <typename _A1>
336351
inline _LIBCPP_INLINE_VISIBILITY
337-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
352+
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
338353
signbit(_A1 __lcpp_x) _NOEXCEPT
339354
{
340355
return ::signbit(static_cast<typename std::__promote<_A1>::type>(__lcpp_x));
341356
}
342357

358+
template <class _A1>
359+
inline _LIBCPP_INLINE_VISIBILITY
360+
typename std::enable_if<
361+
std::is_integral<_A1>::value && std::is_signed<_A1>::value, bool>::type
362+
signbit(_A1 __lcpp_x) _NOEXCEPT
363+
{ return __lcpp_x < 0; }
364+
365+
template <class _A1>
366+
inline _LIBCPP_INLINE_VISIBILITY
367+
typename std::enable_if<
368+
std::is_integral<_A1>::value && !std::is_signed<_A1>::value, bool>::type
369+
signbit(_A1) _NOEXCEPT
370+
{ return false; }
371+
343372
#endif // signbit
344373

345374
// fpclassify
@@ -358,22 +387,34 @@ __libcpp_fpclassify(_A1 __lcpp_x) _NOEXCEPT
358387

359388
template <class _A1>
360389
inline _LIBCPP_INLINE_VISIBILITY
361-
typename std::enable_if<std::is_arithmetic<_A1>::value, int>::type
390+
typename std::enable_if<std::is_floating_point<_A1>::value, int>::type
362391
fpclassify(_A1 __lcpp_x) _NOEXCEPT
363392
{
364393
return __libcpp_fpclassify((typename std::__promote<_A1>::type)__lcpp_x);
365394
}
366395

396+
template <class _A1>
397+
inline _LIBCPP_INLINE_VISIBILITY
398+
typename std::enable_if<std::is_integral<_A1>::value, int>::type
399+
fpclassify(_A1 __lcpp_x) _NOEXCEPT
400+
{ return __lcpp_x == 0 ? FP_ZERO : FP_NORMAL; }
401+
367402
#elif defined(_LIBCPP_MSVCRT)
368403

369404
template <typename _A1>
370405
inline _LIBCPP_INLINE_VISIBILITY
371-
typename std::enable_if<std::is_arithmetic<_A1>::value, int>::type
406+
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
372407
fpclassify(_A1 __lcpp_x) _NOEXCEPT
373408
{
374409
return ::fpclassify(static_cast<typename std::__promote<_A1>::type>(__lcpp_x));
375410
}
376411

412+
template <class _A1>
413+
inline _LIBCPP_INLINE_VISIBILITY
414+
typename std::enable_if<std::is_integral<_A1>::value, int>::type
415+
fpclassify(_A1 __lcpp_x) _NOEXCEPT
416+
{ return __lcpp_x == 0 ? FP_ZERO : FP_NORMAL; }
417+
377418
#endif // fpclassify
378419

379420
// isfinite
@@ -392,12 +433,22 @@ __libcpp_isfinite(_A1 __lcpp_x) _NOEXCEPT
392433

393434
template <class _A1>
394435
inline _LIBCPP_INLINE_VISIBILITY
395-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
436+
typename std::enable_if<
437+
std::is_arithmetic<_A1>::value && std::numeric_limits<_A1>::has_infinity,
438+
bool>::type
396439
isfinite(_A1 __lcpp_x) _NOEXCEPT
397440
{
398441
return __libcpp_isfinite((typename std::__promote<_A1>::type)__lcpp_x);
399442
}
400443

444+
template <class _A1>
445+
inline _LIBCPP_INLINE_VISIBILITY
446+
typename std::enable_if<
447+
std::is_arithmetic<_A1>::value && !std::numeric_limits<_A1>::has_infinity,
448+
bool>::type
449+
isfinite(_A1) _NOEXCEPT
450+
{ return true; }
451+
401452
#endif // isfinite
402453

403454
// isinf
@@ -416,12 +467,22 @@ __libcpp_isinf(_A1 __lcpp_x) _NOEXCEPT
416467

417468
template <class _A1>
418469
inline _LIBCPP_INLINE_VISIBILITY
419-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
470+
typename std::enable_if<
471+
std::is_arithmetic<_A1>::value && std::numeric_limits<_A1>::has_infinity,
472+
bool>::type
420473
isinf(_A1 __lcpp_x) _NOEXCEPT
421474
{
422475
return __libcpp_isinf((typename std::__promote<_A1>::type)__lcpp_x);
423476
}
424477

478+
template <class _A1>
479+
inline _LIBCPP_INLINE_VISIBILITY
480+
typename std::enable_if<
481+
std::is_arithmetic<_A1>::value && !std::numeric_limits<_A1>::has_infinity,
482+
bool>::type
483+
isinf(_A1) _NOEXCEPT
484+
{ return false; }
485+
425486
#endif // isinf
426487

427488
// isnan
@@ -440,12 +501,18 @@ __libcpp_isnan(_A1 __lcpp_x) _NOEXCEPT
440501

441502
template <class _A1>
442503
inline _LIBCPP_INLINE_VISIBILITY
443-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
504+
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
444505
isnan(_A1 __lcpp_x) _NOEXCEPT
445506
{
446507
return __libcpp_isnan((typename std::__promote<_A1>::type)__lcpp_x);
447508
}
448509

510+
template <class _A1>
511+
inline _LIBCPP_INLINE_VISIBILITY
512+
typename std::enable_if<std::is_integral<_A1>::value, bool>::type
513+
isnan(_A1) _NOEXCEPT
514+
{ return false; }
515+
449516
#endif // isnan
450517

451518
// isnormal
@@ -464,12 +531,18 @@ __libcpp_isnormal(_A1 __lcpp_x) _NOEXCEPT
464531

465532
template <class _A1>
466533
inline _LIBCPP_INLINE_VISIBILITY
467-
typename std::enable_if<std::is_arithmetic<_A1>::value, bool>::type
534+
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
468535
isnormal(_A1 __lcpp_x) _NOEXCEPT
469536
{
470537
return __libcpp_isnormal((typename std::__promote<_A1>::type)__lcpp_x);
471538
}
472539

540+
template <class _A1>
541+
inline _LIBCPP_INLINE_VISIBILITY
542+
typename std::enable_if<std::is_integral<_A1>::value, bool>::type
543+
isnormal(_A1 __lcpp_x) _NOEXCEPT
544+
{ return __lcpp_x != 0; }
545+
473546
#endif // isnormal
474547

475548
// isgreater

‎libcxx/test/std/numerics/c.math/cmath.pass.cpp

+33
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,7 @@
1010
// <cmath>
1111

1212
#include <cmath>
13+
#include <limits>
1314
#include <type_traits>
1415
#include <cassert>
1516

@@ -551,6 +552,13 @@ void test_signbit()
551552
static_assert((std::is_same<decltype(std::signbit((long double)0)), bool>::value), "");
552553
static_assert((std::is_same<decltype(signbit(Ambiguous())), Ambiguous>::value), "");
553554
assert(std::signbit(-1.0) == true);
555+
assert(std::signbit(0u) == false);
556+
assert(std::signbit(std::numeric_limits<unsigned>::max()) == false);
557+
assert(std::signbit(0) == false);
558+
assert(std::signbit(1) == false);
559+
assert(std::signbit(-1) == true);
560+
assert(std::signbit(std::numeric_limits<int>::max()) == false);
561+
assert(std::signbit(std::numeric_limits<int>::min()) == true);
554562
}
555563

556564
void test_fpclassify()
@@ -564,6 +572,11 @@ void test_fpclassify()
564572
static_assert((std::is_same<decltype(std::fpclassify((long double)0)), int>::value), "");
565573
static_assert((std::is_same<decltype(fpclassify(Ambiguous())), Ambiguous>::value), "");
566574
assert(std::fpclassify(-1.0) == FP_NORMAL);
575+
assert(std::fpclassify(0) == FP_ZERO);
576+
assert(std::fpclassify(1) == FP_NORMAL);
577+
assert(std::fpclassify(-1) == FP_NORMAL);
578+
assert(std::fpclassify(std::numeric_limits<int>::max()) == FP_NORMAL);
579+
assert(std::fpclassify(std::numeric_limits<int>::min()) == FP_NORMAL);
567580
}
568581

569582
void test_isfinite()
@@ -577,6 +590,11 @@ void test_isfinite()
577590
static_assert((std::is_same<decltype(std::isfinite((long double)0)), bool>::value), "");
578591
static_assert((std::is_same<decltype(isfinite(Ambiguous())), Ambiguous>::value), "");
579592
assert(std::isfinite(-1.0) == true);
593+
assert(std::isfinite(0) == true);
594+
assert(std::isfinite(1) == true);
595+
assert(std::isfinite(-1) == true);
596+
assert(std::isfinite(std::numeric_limits<int>::max()) == true);
597+
assert(std::isfinite(std::numeric_limits<int>::min()) == true);
580598
}
581599

582600
void test_isnormal()
@@ -590,6 +608,11 @@ void test_isnormal()
590608
static_assert((std::is_same<decltype(std::isnormal((long double)0)), bool>::value), "");
591609
static_assert((std::is_same<decltype(isnormal(Ambiguous())), Ambiguous>::value), "");
592610
assert(std::isnormal(-1.0) == true);
611+
assert(std::isnormal(0) == false);
612+
assert(std::isnormal(1) == true);
613+
assert(std::isnormal(-1) == true);
614+
assert(std::isnormal(std::numeric_limits<int>::max()) == true);
615+
assert(std::isnormal(std::numeric_limits<int>::min()) == true);
593616
}
594617

595618
void test_isgreater()
@@ -651,6 +674,11 @@ void test_isinf()
651674
static_assert((std::is_same<decltype(std::isinf(0)), bool>::value), "");
652675
static_assert((std::is_same<decltype(std::isinf((long double)0)), bool>::value), "");
653676
assert(std::isinf(-1.0) == false);
677+
assert(std::isinf(0) == false);
678+
assert(std::isinf(1) == false);
679+
assert(std::isinf(-1) == false);
680+
assert(std::isinf(std::numeric_limits<int>::max()) == false);
681+
assert(std::isinf(std::numeric_limits<int>::min()) == false);
654682
}
655683

656684
void test_isless()
@@ -731,6 +759,11 @@ void test_isnan()
731759
static_assert((std::is_same<decltype(std::isnan(0)), bool>::value), "");
732760
static_assert((std::is_same<decltype(std::isnan((long double)0)), bool>::value), "");
733761
assert(std::isnan(-1.0) == false);
762+
assert(std::isnan(0) == false);
763+
assert(std::isnan(1) == false);
764+
assert(std::isnan(-1) == false);
765+
assert(std::isnan(std::numeric_limits<int>::max()) == false);
766+
assert(std::isnan(std::numeric_limits<int>::min()) == false);
734767
}
735768

736769
void test_isunordered()

0 commit comments

Comments
 (0)
Please sign in to comment.