History log of /freebsd/lib/msun/src/e_rem_pio2f.c (Results 1 – 25 of 83)
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# 07cc7ea7 25-Jun-2024 Ryan Libby <rlibby@FreeBSD.org>

libmsun: remove duplicates after cdefs.h added inline to __always_inline

Reviewed by: kib, olce
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D45712


Revision tags: release/14.1.0
# e75a1bbc 23-Apr-2024 Karl Tomlinson <karlt+@karlt.net>

pow,powf(3),__ieee754_rem_pio2(f): Avoid negative integer left shift UB

A compiler clever enough to know that z is positive with a non-zero
biased exponent could, for example, optimize away the scal

pow,powf(3),__ieee754_rem_pio2(f): Avoid negative integer left shift UB

A compiler clever enough to know that z is positive with a non-zero
biased exponent could, for example, optimize away the scalbnf(z,n) in
pow() because behavior for left shift of negative values is undefined.
`n` is negative when y*log2(|x|) < -0.5. i.e. |x^y| < sqrt(0.5)

The intended behavior for operator<< in this code is to shift the two's
complement representation of the first operand.

In the pow() functions, the result is added to the IEEE 754 exponent of
z = 2^y'. n may be negative enough to underflow the biased IEEE 754
exponent below zero, which is manifested in the sign bit of j
(which would correspond to the IEEE 754 sign bit).

The conversion from uint32_t to int32_t for out-of-int32_t-range values
is implementation defined. The assumed behavior of interpreting the
uint32_t value as a two's complement representation of a signed value
is already assumed in many parts of the code, such as uses of
GET_FLOAT_WORD() with signed integers.

This code passes all the current tests, and makes some out of tree
fuzzing tests pass again rather than hit UB (detailed in the commentary
of the pull request).

Signed-off-by: Karl Tomlinson <karlt+@karlt.net>
Reviewed by: imp, steve kargl, dim
Pull Request: https://github.com/freebsd/freebsd-src/pull/1137

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Revision tags: release/13.3.0
# 0dd5a560 28-Jan-2024 Steve Kargl <kargl@FreeBSD.org>

lib/msun: Cleanup after $FreeBSD$ removal

Remove no longer needed explicit inclusion of sys/cdefs.h.

PR: 276669
MFC after: 1 week


Revision tags: release/14.0.0
# 1d386b48 16-Aug-2023 Warner Losh <imp@FreeBSD.org>

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/


Revision tags: release/13.2.0, release/12.4.0, release/13.1.0, release/12.3.0, release/13.0.0, release/12.2.0, release/11.4.0, release/12.1.0, release/11.3.0, release/12.0.0
# 27aa8442 20-Jul-2018 Bruce Evans <bde@FreeBSD.org>

Centralize the complications for special efficient rounding to integers.

This was open-coded in range reduction for trig and exp functions. Now
there are 3 static inline functions rnint[fl]() that

Centralize the complications for special efficient rounding to integers.

This was open-coded in range reduction for trig and exp functions. Now
there are 3 static inline functions rnint[fl]() that replace open-coded
expressions, and type-generic irint() and i64rint() macros that hide the
complications for efficiently using non-generic irint() and irintl()
functions and casts.

Special details:

ld128/e_rem_pio2l.h needs to use i64rint() since it needs a 46-bit integer
result. Everything else only needs a (less than) 32-bit integer result so
uses irint().

Float and double cases now use float_t and double_t locally instead of
STRICT_ASSIGN() to avoid bugs in extra precision.

On amd64, inline asm is now only used for irint() on long doubles. The SSE
asm for irint() on amd64 only existed because the ifdef tangles made the
correct method of simply casting to int for this case non-obvious.

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Revision tags: release/11.2.0, release/10.4.0, release/11.1.0, release/11.0.1, release/11.0.0, release/10.3.0, release/10.2.0, release/10.1.0, release/9.3.0, release/10.0.0, release/9.2.0, release/8.4.0, release/9.1.0
# e477abf7 27-Nov-2012 Alexander Motin <mav@FreeBSD.org>

MFC @ r241285


# a10c6f55 11-Nov-2012 Neel Natu <neel@FreeBSD.org>

IFC @ r242684


# 23090366 04-Nov-2012 Simon J. Gerraty <sjg@FreeBSD.org>

Sync from head


# 24bf3585 04-Sep-2012 Gleb Smirnoff <glebius@FreeBSD.org>

Merge head r233826 through r240095.


# f049a6cb 11-Aug-2012 Dimitry Andric <dim@FreeBSD.org>

Add __always_inline to __ieee754_rem_pio2() and __ieee754_rem_pio2f(),
since some older versions of gcc refuse to inline these otherwise.

Requested by: bde
MFC after: 1 week


# 2b795b29 11-Aug-2012 Dimitry Andric <dim@FreeBSD.org>

Change a few extern inline functions in libm to static inline, since
they need to refer to static constants, which C99 does not allow for
extern inline functions.

While here, change a comment in e_r

Change a few extern inline functions in libm to static inline, since
they need to refer to static constants, which C99 does not allow for
extern inline functions.

While here, change a comment in e_rem_pio2f.c to mention the correct
number of bits.

Reviewed by: bde
MFC after: 1 week

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Revision tags: release/8.3.0_cvs, release/8.3.0, release/9.0.0, release/7.4.0_cvs, release/8.2.0_cvs, release/7.4.0, release/8.2.0, release/8.1.0_cvs, release/8.1.0, release/7.3.0_cvs, release/7.3.0, release/8.0.0_cvs, release/8.0.0
# 10b3b545 17-Sep-2009 Dag-Erling Smørgrav <des@FreeBSD.org>

Merge from head


# 7d4b968b 17-Sep-2009 Dag-Erling Smørgrav <des@FreeBSD.org>

Merge from head up to r188941 (last revision before the USB stack switch)


# 7e857dd1 12-Jun-2009 Oleksandr Tymoshenko <gonzo@FreeBSD.org>

- Merge from HEAD


# 2e03f452 04-Jun-2009 Jung-uk Kim <jkim@FreeBSD.org>

Resync with head.


# b492f289 03-Jun-2009 Ed Schouten <ed@FreeBSD.org>

Use ISO C99 style inline semantics in msun.

Because we use ISO C99 nowadays, we can just get rid of enforcing
GNU89-style inlining.


Revision tags: release/7.2.0_cvs, release/7.2.0
# bad3b688 18-Jan-2009 Oleksandr Tymoshenko <gonzo@FreeBSD.org>

Sync with head


# 4630140c 13-Jan-2009 David Schultz <das@FreeBSD.org>

Use __gnu89_inline so that these files will compile with newer versions
of gcc, where the meaning of 'inline' was changed to match C99.

Noticed by: rdivacky


Revision tags: release/7.1.0_cvs, release/7.1.0, release/6.4.0_cvs, release/6.4.0
# 941ab616 08-Aug-2008 David Schultz <das@FreeBSD.org>

Remove some unused variables.

Reported by: Intel C Compiler


# a278d990 28-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Fix and improve some magic numbers for the "medium size" case.

e_rem_pio2.c:
This case goes up to about 2**20pi/2, but the comment about it said that
it goes up to about 2**19pi/2.

It went too far

Fix and improve some magic numbers for the "medium size" case.

e_rem_pio2.c:
This case goes up to about 2**20pi/2, but the comment about it said that
it goes up to about 2**19pi/2.

It went too far above 2**pi/2, giving a multiplier fn with 21 significant
bits in some cases. This would be harmful except for a numerical
accident. It happens that the terms of the approximation to pi/2,
when rounded to 33 bits so that multiplications by 20-bit fn's are
exact, happen to be rounded to 32 bits so multiplications by 21-bit
fn's are exact too, so the bug only complicates the error analysis (we
might lose a bit of accuracy but have bits to spare).

e_rem_pio2f.c:
The bogus comment in e_rem_pio2.c was copied and the code was changed
to be bug-for-bug compatible with it, except the limit was made 90
ulps smaller than necessary. The approximation to pi/2 was not
modified except for discarding some of it.

The same rough error analysis that justifies the limit of 2**20pi/2
for double precision only justifies a limit of 2**18pi/2 for float
precision. We depended on exhaustive testing to check the magic numbers
for float precision. More exaustive testing shows that we can go up
to 2**28pi/2 using a 53+25 bit approximation to pi/2 for float precision,
with a the maximum error for cosf() and sinf() unchanged at 0.5009
ulps despite the maximum error in rem_pio2f being ~0.25 ulps. Implement
this.

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# e822ea5b 25-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Inline __ieee754__rem_pio2f(). On amd64 (A64) and i386 (A64), this
gives an average speedup of about 12 cycles or 17% for
9pi/4 < |x| <= 2**19pi/2 and a smaller speedup for larger x, and a
small spe

Inline __ieee754__rem_pio2f(). On amd64 (A64) and i386 (A64), this
gives an average speedup of about 12 cycles or 17% for
9pi/4 < |x| <= 2**19pi/2 and a smaller speedup for larger x, and a
small speeddown for |x| <= 9pi/4 (only 1-2 cycles average, but that
is 4%).

Inlining this is less likely to bust caches than inlining the float
version since it is much smaller (about 220 bytes text and rodata) and
has many fewer branches. However, the float version was already large
due to its manual inlining of the branches and also the polynomial
evaluations.

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# c32951b1 25-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Use a temporary array instead of the arg array y[] for calling
__kernel_rem_pio2(). This simplifies analysis of aliasing and thus
results in better code for the usual case where __kernel_rem_pio2()

Use a temporary array instead of the arg array y[] for calling
__kernel_rem_pio2(). This simplifies analysis of aliasing and thus
results in better code for the usual case where __kernel_rem_pio2()
is not called. In particular, when __ieee854_rem_pio2[f]() is inlined,
it normally results in y[] being returned in registers. I couldn't
get this to work using the restrict qualifier.

In float precision, this saves 2-3% in most cases on amd64 and i386
(A64) despite it not being inlined in float precision yet. In double
precision, this has high variance, with an average gain of 2% for
amd64 and 0.7% for i386 (but a much larger gain for usual cases) and
some losses.

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# 70d818a2 25-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Change __ieee754_rem_pio2f() to return double instead of float so that
this function and its callers cosf(), sinf() and tanf() don't waste time
converting values from doubles to floats and back for |

Change __ieee754_rem_pio2f() to return double instead of float so that
this function and its callers cosf(), sinf() and tanf() don't waste time
converting values from doubles to floats and back for |x| > 9pi/4.
All these functions were optimized a few years ago to mostly use doubles
internally and across the __kernel*() interfaces but not across the
__ieee754_rem_pio2f() interface.

This saves about 40 cycles in cosf(), sinf() and tanf() for |x| > 9pi/4
on amd64 (A64), and about 20 cycles on i386 (A64) (except for cosf()
and sinf() in the upper range). 40 cycles is about 35% for |x| < 9pi/4
<= 2**19pi/2 and about 5% for |x| > 2**19pi/2. The saving is much
larger on amd64 than on i386 since the conversions are not easy to
optimize except on i386 where some of them are automatic and others
are optimized invalidly. amd64 is still about 10% slower in cosf()
and tanf() in the lower range due to conversion overhead.

This also gives a tiny speedup for |x| <= 9pi/4 on amd64 (by simplifying
the code). It also avoids compiler bugs and/or additional slowness
in the conversions on (not yet supported) machines where double_t !=
double.

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# 0d1564b6 25-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Fix some off-by-1 errors.

e_rem_pio2.c:
Float and double precision didn't work because init_jk[] was 1 too small.
It needs to be 2 larger than you might expect, and 1 larger than it was
for these pr

Fix some off-by-1 errors.

e_rem_pio2.c:
Float and double precision didn't work because init_jk[] was 1 too small.
It needs to be 2 larger than you might expect, and 1 larger than it was
for these precisions, since its test for recomputing needs a margin of
47 bits (almost 2 24-bit units).

init_jk[] seems to be barely enough for extended and quad precisions.
This hasn't been completely verified. Callers now get about 24 bits
of extra precision for float, and about 19 for double, but only about
8 for extended and quad. 8 is not enough for callers that want to
produce extra-precision results, but current callers have rounding
errors of at least 0.8 ulps, so another 1/2**8 ulps of error from the
reduction won't affect them much.

Add a comment about some of the magic for init_jk[].

e_rem_pio2.c:
Double precision worked in practice because of a compensating off-by-1
error here. Extended precision was asked for, and it executed exactly
the same code as the unbroken double precision.

e_rem_pio2f.c:
Float precision worked in practice because of a compensating off-by-1
error here. Double precision was asked for, and was almost needed,
since the cosf() and sinf() callers want to produce extra-precision
results, at least internally so that their error is only 0.5009 ulps.
However, the extra precision provided by unbroken float precision is
enough, and the double-precision code has extra overheads, so the
off-by-1 error cost about 5% in efficiency on amd64 and i386.

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Revision tags: release/7.0.0_cvs, release/7.0.0
# 60a50c25 23-Feb-2008 Bruce Evans <bde@FreeBSD.org>

Optimize the 9pi/2 < |x| <= 2**19pi/2 case some more by avoiding an
fabs(), a conditional branch, and sign adjustments of 3 variables for
x < 0 when the branch is taken. In double precision, even wh

Optimize the 9pi/2 < |x| <= 2**19pi/2 case some more by avoiding an
fabs(), a conditional branch, and sign adjustments of 3 variables for
x < 0 when the branch is taken. In double precision, even when the
branch is perfectly predicted, this saves about 10 cycles or 10% on
amd64 (A64) and i386 (A64) for the negative half of the range, but
makes little difference for the positive half of the range. In float
precision, it also saves about 4 cycles for the positive half of the
range on i386, and many more cycles in both halves on amd64 (28 in the
negative half and 11 in the positive half for tanf), but the amd64
times for float precision are anomalously slow so the larger
improvement is only a side effect.

Previous commits arranged for the x < 0 case to be handled simply:
- one part of the rounding method uses the magic number 0x1.8p52
instead of the usual 0x1.0p52. The latter is required for large |x|,
but it doesn't work for negative x and we don't need it for large |x|.
- another part of the rounding method no longer needs to add `half'.
It would have needed to add -half for negative x.
- removing the "quick check no cancellation" in the double precision
case removed the need to take the absolute value of the quadrant
number.

Add my noncopyright in e_rem_pio2.c

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