Add narrowing subtract functions.

This patch adds the narrowing subtract functions from TS 18661-1 to
glibc's libm: fsub, fsubl, dsubl, f32subf64, f32subf32x, f32xsubf64
for all configurations; f32subf64x, f32subf128, f64subf64x,
f64subf128, f32xsubf64x, f32xsubf128, f64xsubf128 for configurations
with _Float64x and _Float128; __nldbl_dsubl for ldbl-opt.

The changes are essentially the same as for the narrowing add
functions, so the description of those generally applies to this patch
as well.

Tested for x86_64, x86, mips64 (all three ABIs, both hard and soft
float) and powerpc, and with build-many-glibcs.py.

	* math/Makefile (libm-narrow-fns): Add sub.
	(libm-test-funcs-narrow): Likewise.
	* math/Versions (GLIBC_2.28): Add narrowing subtract functions.
	* math/bits/mathcalls-narrow.h (sub): Use __MATHCALL_NARROW.
	* math/gen-auto-libm-tests.c (test_functions): Add sub.
	* math/math-narrow.h (CHECK_NARROW_SUB): New macro.
	(NARROW_SUB_ROUND_TO_ODD): Likewise.
	(NARROW_SUB_TRIVIAL): Likewise.
	* sysdeps/ieee754/float128/float128_private.h (__fsubl): New
	macro.
	(__dsubl): Likewise.
	* sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add fsub and
	dsub.
	(CFLAGS-nldbl-dsub.c): New variable.
	(CFLAGS-nldbl-fsub.c): Likewise.
	* sysdeps/ieee754/ldbl-opt/Versions (GLIBC_2.28): Add
	__nldbl_dsubl.
	* sysdeps/ieee754/ldbl-opt/nldbl-compat.h (__nldbl_dsubl): New
	prototype.
	* manual/arith.texi (Misc FP Arithmetic): Document fsub, fsubl,
	dsubl, fMsubfN, fMsubfNx, fMxsubfN and fMxsubfNx.
	* math/auto-libm-test-in: Add tests of sub.
	* math/auto-libm-test-out-narrow-sub: New generated file.
	* math/libm-test-narrow-sub.inc: New file.
	* sysdeps/i386/fpu/s_f32xsubf64.c: Likewise.
	* sysdeps/ieee754/dbl-64/s_f32xsubf64.c: Likewise.
	* sysdeps/ieee754/dbl-64/s_fsub.c: Likewise.
	* sysdeps/ieee754/float128/s_f32subf128.c: Likewise.
	* sysdeps/ieee754/float128/s_f64subf128.c: Likewise.
	* sysdeps/ieee754/float128/s_f64xsubf128.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_dsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_f64xsubf128.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_fsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_dsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_fsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-96/s_dsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-96/s_fsubl.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/nldbl-dsub.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/nldbl-fsub.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_dsubl.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_fsub.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_fsubl.c: Likewise.
	* sysdeps/powerpc/fpu/libm-test-ulps: Update.
	* sysdeps/mach/hurd/i386/libm.abilist: Likewise.
	* 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/riscv/rv64/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/tilegx32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.

1 files changed, 95 insertions, 0 deletions

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index fc407e9..bb3c325 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -7195,6 +7195,101 @@ sinh 0x2.c5d37700c6bb03a8p+12 no-test-inline
 sinh 0x2.c5d37700c6bb03a6c24b6c9b494cp+12 no-test-inline
 sinh 0x2.c5d37700c6bb03a6c24b6c9b494ep+12 no-test-inline
 
+sub 0 0
+sub 0 -0
+sub -0 0
+sub -0 -0
+sub max max
+sub max -max
+sub -max max
+sub -max -max
+sub min min missing-underflow:arg-ibm128
+sub min -min missing-underflow:arg-ibm128
+sub -min min missing-underflow:arg-ibm128
+sub -min -min missing-underflow:arg-ibm128
+sub min_subnorm min_subnorm missing-underflow:arg-ibm128
+sub min_subnorm -min_subnorm missing-underflow:arg-ibm128
+sub -min_subnorm min_subnorm missing-underflow:arg-ibm128
+sub -min_subnorm -min_subnorm missing-underflow:arg-ibm128
+sub 1 2
+sub 1 -2
+sub -1 2
+sub -1 -2
+sub 100.5 0.75
+sub 100.5 -0.75
+sub -100.5 0.75
+sub -100.5 -0.75
+sub 1 0x1p-23
+sub 1 0x1.7fp-23
+sub 1 0x1.8p-23
+sub 1 0x1.81p-23
+sub 1 0x1p-24
+sub 1 0x1.1p-24
+sub 1 0x0.fp-24
+sub 1 min
+sub 1 -min
+sub 1 min_subnorm
+sub 1 -min_subnorm
+sub -1 min
+sub -1 -min
+sub -1 min_subnorm
+sub -1 -min_subnorm
+# Cases where larger argument is half way between two values of a
+# floating-point format, so that double rounding would sometimes yield
+# the wrong result.
+sub 0x1.000001p0 min
+sub 0x1.000001p0 -min
+sub 0x1.000001p0 min_subnorm
+sub 0x1.000001p0 -min_subnorm
+sub -0x1.000001p0 min
+sub -0x1.000001p0 -min
+sub -0x1.000001p0 min_subnorm
+sub -0x1.000001p0 -min_subnorm
+sub 0x1.00000000000008p0 min
+sub 0x1.00000000000008p0 -min
+sub 0x1.00000000000008p0 min_subnorm
+sub 0x1.00000000000008p0 -min_subnorm
+sub -0x1.00000000000008p0 min
+sub -0x1.00000000000008p0 -min
+sub -0x1.00000000000008p0 min_subnorm
+sub -0x1.00000000000008p0 -min_subnorm
+sub 0x1.0000000000000001p0 min
+sub 0x1.0000000000000001p0 -min
+sub 0x1.0000000000000001p0 min_subnorm
+sub 0x1.0000000000000001p0 -min_subnorm
+sub -0x1.0000000000000001p0 min
+sub -0x1.0000000000000001p0 -min
+sub -0x1.0000000000000001p0 min_subnorm
+sub -0x1.0000000000000001p0 -min_subnorm
+# Two values representable in the same format with difference very
+# close to half way between two representable values.  In particular,
+# verify that there is no intermediate rounding to 64 bits when
+# subtracting two double values.
+sub 1 0x1.000002p-24
+sub 1 -0x1.000002p-24
+sub 1 0x0.ffffffp-24
+sub 1 -0x0.ffffffp-24
+sub 0x1.000002p0 0x1.000002p-24
+sub 0x1.000002p0 -0x1.000002p-24
+sub 0x1.000002p0 0x0.ffffffp-24
+sub 0x1.000002p0 -0x0.ffffffp-24
+sub 1 0x1.0000000000001p-53
+sub 1 -0x1.0000000000001p-53
+sub 1 0x0.fffffffffffff8p-53
+sub 1 -0x0.fffffffffffff8p-53
+sub 0x1.0000000000001p0 0x1.0000000000001p-53
+sub 0x1.0000000000001p0 -0x1.0000000000001p-53
+sub 0x1.0000000000001p0 0x0.fffffffffffff8p-53
+sub 0x1.0000000000001p0 -0x0.fffffffffffff8p-53
+sub 1 0x1.0000000000000002p-64
+sub 1 -0x1.0000000000000002p-64
+sub 1 0x0.ffffffffffffffffp-64
+sub 1 -0x0.ffffffffffffffffp-64
+sub 0x1.0000000000000002p0 0x1.0000000000000002p-64
+sub 0x1.0000000000000002p0 -0x1.0000000000000002p-64
+sub 0x1.0000000000000002p0 0x0.ffffffffffffffffp-64
+sub 0x1.0000000000000002p0 -0x0.ffffffffffffffffp-64
+
 sqrt 0
 sqrt -0
 sqrt 2209