TS 18661-1 defines canonicalize functions to produce a canonical
version of a floating-point representation. This patch implements
these functions for glibc.
As with the iscanonical macro, these functions are oriented to the
decimal floating-point case, where some values have both canonical and
noncanonical representations. However, the functions have a return
value that says whether they succeeded in storing a canonical result;
thus, they can fail for the case of an invalid representation (while
still not making any particular choice from among multiple equally
canonical valid representations of the same value). Since no
floating-point formats in glibc actually have noncanonical valid
representations, a type-generic implementation of these functions can
be used that expects iscanonical to return 0 only for invalid
representations. Now that iscanonical is used within libm.so,
libm_hidden_proto / libm_hidden_def are added for __iscanonicall.
The definition of these functions is intended to correspond to a
convertFormat operation to the same floating-point format. Thus, they
convert signaling NaNs to quiet NaNs, raising the "invalid" exception.
Such a conversion "should" produce "the canonical version of that
signaling NaN made quiet".
libm-test.inc is made to check NaN payloads for the output of these
functions, a new feature (at some point manipulation functions such as
fabs and copysign should have tests added that verify payload
preservation for them). As however some architectures may not follow
the recommended practice of preserving NaN payloads when converting a
signaling NaN to quiet, a new math-tests.h macro
SNAN_TESTS_PRESERVE_PAYLOAD is added, and defined to 0 for non-NAN2008
MIPS; any other architectures seeing test failures for lack of payload
preservation in this case should also define this macro to 0. (If any
cases arise where the sign isn't preserved either, those should have a
similar macro added.)
The ldbl-96 and ldbl-128ibm tests of iscanonical are renamed and
adapted to test canonicalizel as well on the same representations.
Tested for x86_64, x86, mips64 and powerpc.
* math/bits/mathcalls.h [__GLIBC_USE (IEC_60559_BFP_EXT)]
(canonicalize): New declaration.
* math/Versions (canonicalize): New libm symbol at version
GLIBC_2.25.
(canonicalizef): Likewise.
(canonicalizel): Likewise.
* math/Makefile (gen-libm-calls): Add s_canonicalizeF.
* math/s_canonicalize_template.c: New file.
* math/libm-test.inc: Update comment on functions tested and
testing of NaN payloads.
(TEST_NAN_PAYLOAD): New macro.
(NO_TEST_INLINE): Update value.
(XFAIL_TEST): Likewise.
(ERRNO_UNCHANGED): Likewise.
(ERRNO_EDOM): Likewise.
(ERRNO_ERANGE): Likewise.
(IGNORE_RESULT): Likewise.
(NON_FINITE): Likewise.
(TEST_SNAN): Likewise.
(NO_TEST_MATHVEC): Likewise.
(TEST_NAN_PAYLOAD_CANONICALIZE): New macro.
(check_float_internal): Check NaN payloads if TEST_NAN_PAYLOAD.
(struct test_Ffp_b1_data): New type.
(RUN_TEST_Ffp_b1): New macro.
(RUN_TEST_LOOP_Ffp_b1): Likewise.
(canonicalize_test_data): New array.
(canonicalize_test): New function.
(main): Call canonicalize_test.
* manual/arith.texi (FP Bit Twiddling): Document canonicalize,
canonicalizef and canonicalizel.
* manual/libm-err-tab.pl: Update comment on interfaces without
ulps tabulated.
* sysdeps/ieee754/ldbl-opt/nldbl-canonicalize.c: New file.
* sysdeps/ieee754/ldbl-opt/s_canonicalizel.c: Likewise.
* sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add
canonicalize.
(CFLAGS-nldbl-canonicalize.c): New variable.
* sysdeps/ieee754/ldbl-128ibm/test-iscanonical-ldbl-128ibm.c: Move
to ...
* sysdeps/ieee754/ldbl-128ibm/test-canonical-ldbl-128ibm.c:
... here.
(do_test): Also test canonicalizel.
* sysdeps/ieee754/ldbl-128ibm/Makefile (tests): Change
test-iscanonical-ldbl-128ibm to test-canonical-ldbl-128ibm.
* sysdeps/ieee754/ldbl-128ibm/include/bits/iscanonical.h: New
file.
* sysdeps/ieee754/ldbl-128ibm/s_iscanonicall.c (__iscanonicall):
Use libm_hidden_def.
* sysdeps/ieee754/ldbl-96/test-iscanonical-ldbl-96.c: Move to ...
* sysdeps/ieee754/ldbl-96/test-canonical-ldbl-96.c: ... here.
(do_test): Also test canonicalizel.
* sysdeps/ieee754/ldbl-96/Makefile (tests): Change
test-iscanonical-ldbl-96 to test-canonical-ldbl-96.
* sysdeps/ieee754/ldbl-96/include/bits/iscanonical.h: New file.
* sysdeps/ieee754/ldbl-96/s_iscanonicall.c (__iscanonicall): Use
libm_hidden_def.
* sysdeps/generic/math-tests.h (SNAN_TESTS_PRESERVE_PAYLOAD): New
macro.
* sysdeps/mips/math-tests.h [__mips_hard_float && !__mips_nan2008]
(SNAN_TESTS_PRESERVE_PAYLOAD): Likewise.
* sysdeps/nacl/libm.abilist: Update.
* sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.
TS 18661-1 adds an iscanonical classification macro to <math.h>.
The motivation for this is decimal floating-point, where some values
have both canonical and noncanonical encodings. For IEEE binary
interchange formats, all encodings are canonical. For x86/m68k
ldbl-96, and for ldbl-128ibm, there are encodings that do not
represent any valid value of the type; although formally iscanonical
does not need to handle trap representations (and so could just always
return 1), it seems useful, and in line with the description in the TS
of "representations that are extraneous to the floating-point model"
as being non-canonical (as well as "redundant representations of some
or all of its values"), for it to detect those representations and
return 0 for them.
This patch adds iscanonical to glibc. It goes in a header
<bits/iscanonical.h>, included under appropriate conditions in
<math.h>. The default header version just evaluates the argument
(converted to its semantic type, though current GCC will probably
discard that conversion and any exceptions resulting from it) and
returns 1. ldbl-96 and ldbl-128ibm then have versions of the header
that call a function __iscanonicall for long double (the sizeof-based
tests will of course need updating for float128 support, like other
such type-generic macro implementations). The ldbl-96 version of
__iscanonicall has appropriate conditionals to reflect the differences
in the m68k version of that format (where the high mantissa bit may be
either 0 or 1 when the exponent is 0 or 0x7fff). Corresponding tests
for those formats are added as well. Other architectures do not have
any new functions added because just returning 1 is correct for all
their floating-point formats.
Tested for x86_64, x86, mips64 (to test the default macro version) and
powerpc.
* math/math.h [__GLIBC_USE (IEC_60559_BFP_EXT)]: Include
<bits/iscanonical.h>.
* bits/iscanonical.h: New file.
* math/s_iscanonicall.c: Likewise.
* math/Versions (__iscanonicall): New libm symbol at version
GLIBC_2.25.
* math/libm-test.inc (iscanonical_test_data): New array.
(iscanonical_test): New function.
(main): Call iscanonical_test.
* math/Makefile (headers): Add bits/iscanonical.h.
(type-ldouble-routines): Add s_iscanonicall.
* manual/arith.texi (Floating Point Classes): Document
iscanonical.
* manual/libm-err-tab.pl: Update comment on interfaces without
ulps tabulated.
* sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h: New file.
* sysdeps/ieee754/ldbl-128ibm/s_iscanonicall.c: Likewise.
* sysdeps/ieee754/ldbl-128ibm/test-iscanonical-ldbl-128ibm.c:
Likewise.
* sysdeps/ieee754/ldbl-128ibm/Makefile (tests): Add
test-iscanonical-ldbl-128ibm.
* sysdeps/ieee754/ldbl-96/bits/iscanonical.h: New file.
* sysdeps/ieee754/ldbl-96/s_iscanonicall.c: Likewise.
* sysdeps/ieee754/ldbl-96/test-iscanonical-ldbl-96.c: Likewise.
* sysdeps/ieee754/ldbl-96/Makefile: Likewise.
* sysdeps/unix/sysv/linux/i386/libm.abilist: Update.
* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist:
Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.
Joseph Myers