Implement C23 rsqrt

C23 adds various <math.h> function families originally defined in TS
18661-4.  Add the rsqrt functions (1/sqrt(x)).  The test inputs are
taken from those for sqrt.

Tested for x86_64 and x86, and with build-many-glibcs.py.

50 files changed, 3865 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index e2e40e141c..29d3d47b64 100644
--- a/NEWS
+++ b/NEWS
@@ -9,7 +9,12 @@ Version 2.42
 
 Major new features:
 
-  [Add new features here]
+* The following ISO C23 function families (introduced in TS
+  18661-4:2015) are now supported in <math.h>.  Each family includes
+  functions for float, double, long double, _FloatN and _FloatNx, and a
+  type-generic macro in <tgmath.h>.
+
+  - Power and absolute-value functions: rsqrt.
 
 Deprecated and removed features, and other changes affecting compatibility:
 
diff --git a/manual/math.texi b/manual/math.texi
index def85a973d..439f608360 100644
--- a/manual/math.texi
+++ b/manual/math.texi
@@ -790,6 +790,19 @@ If @var{x} is negative, @code{sqrt} signals a domain error.
 Mathematically, it should return a complex number.
 @end deftypefun
 
+@deftypefun double rsqrt (double @var{x})
+@deftypefunx float rsqrtf (float @var{x})
+@deftypefunx {long double} rsqrtl (long double @var{x})
+@deftypefunx _FloatN rsqrtfN (_Float@var{N} @var{x})
+@deftypefunx _FloatNx rsqrtfNx (_Float@var{N}x @var{x})
+@standards{TS 18661-4:2015, math.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+These functions return the reciprocal of the nonnegative square root of @var{x}.
+If @var{x} is negative, @code{rsqrt} signals a domain error.
+
+The @code{rsqrt} functions are from TS 18661-4:2015.
+@end deftypefun
+
 @cindex cube root function
 @deftypefun double cbrt (double @var{x})
 @deftypefunx float cbrtf (float @var{x})
diff --git a/math/Makefile b/math/Makefile
index 6dab60095b..7aabf355b4 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -139,6 +139,7 @@ gen-libm-calls = \
   s_log2p1F \
   s_nanF \
   s_nextdownF \
+  s_rsqrtF \
   s_significandF \
   s_sinpiF \
   s_tanpiF \
@@ -682,6 +683,7 @@ libm-test-funcs-auto = \
   log1p \
   log2p1 \
   pow \
+  rsqrt \
   sin \
   sincos \
   sinh \
@@ -1017,6 +1019,7 @@ tgmath3-macros = \
   rint \
   round \
   roundeven \
+  rsqrt \
   scalb \
   scalbln \
   scalbn \
@@ -1462,6 +1465,7 @@ CFLAGS-s_remquo.c += -fno-builtin-remquol
 CFLAGS-s_rint.c += -fno-builtin-rintl
 CFLAGS-s_round.c += -fno-builtin-roundl
 CFLAGS-s_roundeven.c += -fno-builtin-roundevenl
+CFLAGS-s_rsqrt.c += -fno-builtin-rsqrtl
 CFLAGS-w_scalb.c += -fno-builtin-scalbl
 CFLAGS-w_scalbln.c += -fno-builtin-scalblnl
 CFLAGS-s_scalbn.c += -fno-builtin-scalbnl
@@ -1596,6 +1600,7 @@ CFLAGS-s_remquo.c += -fno-builtin-remquof32x -fno-builtin-remquof64
 CFLAGS-s_rint.c += -fno-builtin-rintf32x -fno-builtin-rintf64
 CFLAGS-s_round.c += -fno-builtin-roundf32x -fno-builtin-roundf64
 CFLAGS-s_roundeven.c += -fno-builtin-roundevenf32x -fno-builtin-roundevenf64
+CFLAGS-s_rsqrt.c += -fno-builtin-rsqrtf32x -fno-builtin-rsqrtf64
 CFLAGS-w_scalbln.c += -fno-builtin-scalblnf32x -fno-builtin-scalblnf64
 CFLAGS-s_scalbn.c += -fno-builtin-scalbnf32x -fno-builtin-scalbnf64
 CFLAGS-s_setpayload.c += -fno-builtin-setpayloadf32x -fno-builtin-setpayloadf64
@@ -1721,6 +1726,7 @@ CFLAGS-s_remquof.c += -fno-builtin-remquof32
 CFLAGS-s_rintf.c += -fno-builtin-rintf32
 CFLAGS-s_roundf.c += -fno-builtin-roundf32
 CFLAGS-s_roundevenf.c += -fno-builtin-roundevenf32
+CFLAGS-s_rsqrtf.c += -fno-builtin-rsqrtf32
 CFLAGS-w_scalblnf.c += -fno-builtin-scalblnf32
 CFLAGS-s_scalbnf.c += -fno-builtin-scalbnf32
 CFLAGS-s_setpayloadf.c += -fno-builtin-setpayloadf32
diff --git a/math/Versions b/math/Versions
index e4fbef3f6d..34cdf2f8e8 100644
--- a/math/Versions
+++ b/math/Versions
@@ -671,4 +671,10 @@ libm {
     sinpif64x; sinpif128;
     tanpif64x; tanpif128;
   }
+  GLIBC_2.42 {
+    # Functions not involving _Float64x or _Float128, for all configurations.
+    rsqrt; rsqrtf; rsqrtl; rsqrtf32; rsqrtf64; rsqrtf32x;
+    # Functions involving _Float64x or _Float128, for some configurations.
+    rsqrtf64x; rsqrtf128;
+  }
 }
diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 7dd9cde9c9..989ce5d736 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -8151,6 +8151,74 @@ pow 0x1.059c76p+0 0x1.ff80bep+11
 pow 0x1.7ac7cp+5 23
 pow -0x1.7ac7cp+5 23
 
+rsqrt 2209
+rsqrt 4
+rsqrt 2
+rsqrt 0.25
+rsqrt 6642.25
+rsqrt 15190.5625
+rsqrt 0.75
+rsqrt 0x1.fffffffffffffp+1023
+rsqrt 0x1.ffffffffffffbp+1023
+rsqrt 0x1.ffffffffffff7p+1023
+rsqrt 0x1.ffffffffffff3p+1023
+rsqrt 0x1.fffffffffffefp+1023
+rsqrt 0x1.fffffffffffebp+1023
+rsqrt 0x1.fffffffffffe7p+1023
+rsqrt 0x1.fffffffffffe3p+1023
+rsqrt 0x1.fffffffffffdfp+1023
+rsqrt 0x1.fffffffffffdbp+1023
+rsqrt 0x1.fffffffffffd7p+1023
+rsqrt 0x1.0000000000003p-1022
+rsqrt 0x1.0000000000007p-1022
+rsqrt 0x1.000000000000bp-1022
+rsqrt 0x1.000000000000fp-1022
+rsqrt 0x1.0000000000013p-1022
+rsqrt 0x1.0000000000017p-1022
+rsqrt 0x1.000000000001bp-1022
+rsqrt 0x1.000000000001fp-1022
+rsqrt 0x1.0000000000023p-1022
+rsqrt 0x1.0000000000027p-1022
+rsqrt 0x1.000000000002bp-1022
+rsqrt 0x1.000000000002fp-1022
+rsqrt 0x1.0000000000033p-1022
+rsqrt 0x1.0000000000037p-1022
+rsqrt 0x1.7167bc36eaa3bp+6
+rsqrt 0x1.7570994273ad7p+6
+rsqrt 0x1.7dae969442fe6p+6
+rsqrt 0x1.7f8444fcf67e5p+6
+rsqrt 0x1.8364650e63a54p+6
+rsqrt 0x1.85bedd274edd8p+6
+rsqrt 0x1.8609cf496ab77p+6
+rsqrt 0x1.873849c70a375p+6
+rsqrt 0x1.8919c962cbaaep+6
+rsqrt 0x1.8de4493e22dc6p+6
+rsqrt 0x1.924829a17a288p+6
+rsqrt 0x1.92702cd992f12p+6
+rsqrt 0x1.92b763a8311fdp+6
+rsqrt 0x1.947da013c7293p+6
+rsqrt 0x1.9536091c494d2p+6
+rsqrt 0x1.61b04c6p-1019
+rsqrt 0x1.93789f1p-1018
+rsqrt 0x1.a1989b4p-1018
+rsqrt 0x1.f93bc9p-1018
+rsqrt 0x1.2f675e3p-1017
+rsqrt 0x1.a158508p-1017
+rsqrt 0x1.cd31f078p-1017
+rsqrt 0x1.33b43b08p-1016
+rsqrt 0x1.6e66a858p-1016
+rsqrt 0x1.8661cbf8p-1016
+rsqrt 0x1.bbb221b4p-1016
+rsqrt 0x1.c4942f3cp-1016
+rsqrt 0x1.dbb258c8p-1016
+rsqrt 0x1.57103ea4p-1015
+rsqrt 0x1.9b294f88p-1015
+rsqrt 0x1.0000000000001p+0
+rsqrt 0x1.fffffffffffffp-1
+rsqrt max
+rsqrt min
+rsqrt min_subnorm
+
 sin 0
 sin -0
 sin pi/6
diff --git a/math/auto-libm-test-out-rsqrt b/math/auto-libm-test-out-rsqrt
new file mode 100644
index 0000000000..cc28e827c3
--- /dev/null
+++ b/math/auto-libm-test-out-rsqrt
@@ -0,0 +1,3375 @@
+rsqrt 2209
+= rsqrt downward binary32 0x8.a1p+8 : 0x5.726208p-8 : inexact
+= rsqrt tonearest binary32 0x8.a1p+8 : 0x5.726208p-8 : inexact
+= rsqrt towardzero binary32 0x8.a1p+8 : 0x5.726208p-8 : inexact
+= rsqrt upward binary32 0x8.a1p+8 : 0x5.72621p-8 : inexact
+= rsqrt downward binary64 0x8.a1p+8 : 0x5.72620ae4c415cp-8 : inexact
+= rsqrt tonearest binary64 0x8.a1p+8 : 0x5.72620ae4c415cp-8 : inexact
+= rsqrt towardzero binary64 0x8.a1p+8 : 0x5.72620ae4c415cp-8 : inexact
+= rsqrt upward binary64 0x8.a1p+8 : 0x5.72620ae4c416p-8 : inexact
+= rsqrt downward intel96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt tonearest intel96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt towardzero intel96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt upward intel96 0x8.a1p+8 : 0x5.72620ae4c415c99p-8 : inexact
+= rsqrt downward m68k96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt tonearest m68k96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt towardzero m68k96 0x8.a1p+8 : 0x5.72620ae4c415c988p-8 : inexact
+= rsqrt upward m68k96 0x8.a1p+8 : 0x5.72620ae4c415c99p-8 : inexact
+= rsqrt downward binary128 0x8.a1p+8 : 0x5.72620ae4c415c9882b931057262p-8 : inexact
+= rsqrt tonearest binary128 0x8.a1p+8 : 0x5.72620ae4c415c9882b931057262p-8 : inexact
+= rsqrt towardzero binary128 0x8.a1p+8 : 0x5.72620ae4c415c9882b931057262p-8 : inexact
+= rsqrt upward binary128 0x8.a1p+8 : 0x5.72620ae4c415c9882b9310572624p-8 : inexact
+= rsqrt downward ibm128 0x8.a1p+8 : 0x5.72620ae4c415c9882b93105726p-8 : inexact
+= rsqrt tonearest ibm128 0x8.a1p+8 : 0x5.72620ae4c415c9882b93105726p-8 : inexact
+= rsqrt towardzero ibm128 0x8.a1p+8 : 0x5.72620ae4c415c9882b93105726p-8 : inexact
+= rsqrt upward ibm128 0x8.a1p+8 : 0x5.72620ae4c415c9882b93105728p-8 : inexact
+rsqrt 4
+= rsqrt downward binary32 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest binary32 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero binary32 0x4p+0 : 0x8p-4 :
+= rsqrt upward binary32 0x4p+0 : 0x8p-4 :
+= rsqrt downward binary64 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest binary64 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero binary64 0x4p+0 : 0x8p-4 :
+= rsqrt upward binary64 0x4p+0 : 0x8p-4 :
+= rsqrt downward intel96 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest intel96 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero intel96 0x4p+0 : 0x8p-4 :
+= rsqrt upward intel96 0x4p+0 : 0x8p-4 :
+= rsqrt downward m68k96 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest m68k96 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero m68k96 0x4p+0 : 0x8p-4 :
+= rsqrt upward m68k96 0x4p+0 : 0x8p-4 :
+= rsqrt downward binary128 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest binary128 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero binary128 0x4p+0 : 0x8p-4 :
+= rsqrt upward binary128 0x4p+0 : 0x8p-4 :
+= rsqrt downward ibm128 0x4p+0 : 0x8p-4 :
+= rsqrt tonearest ibm128 0x4p+0 : 0x8p-4 :
+= rsqrt towardzero ibm128 0x4p+0 : 0x8p-4 :
+= rsqrt upward ibm128 0x4p+0 : 0x8p-4 :
+rsqrt 2
+= rsqrt downward binary32 0x2p+0 : 0xb.504f3p-4 : inexact
+= rsqrt tonearest binary32 0x2p+0 : 0xb.504f3p-4 : inexact
+= rsqrt towardzero binary32 0x2p+0 : 0xb.504f3p-4 : inexact
+= rsqrt upward binary32 0x2p+0 : 0xb.504f4p-4 : inexact
+= rsqrt downward binary64 0x2p+0 : 0xb.504f333f9de6p-4 : inexact
+= rsqrt tonearest binary64 0x2p+0 : 0xb.504f333f9de68p-4 : inexact
+= rsqrt towardzero binary64 0x2p+0 : 0xb.504f333f9de6p-4 : inexact
+= rsqrt upward binary64 0x2p+0 : 0xb.504f333f9de68p-4 : inexact
+= rsqrt downward intel96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt tonearest intel96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt towardzero intel96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt upward intel96 0x2p+0 : 0xb.504f333f9de6485p-4 : inexact
+= rsqrt downward m68k96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt tonearest m68k96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt towardzero m68k96 0x2p+0 : 0xb.504f333f9de6484p-4 : inexact
+= rsqrt upward m68k96 0x2p+0 : 0xb.504f333f9de6485p-4 : inexact
+= rsqrt downward binary128 0x2p+0 : 0xb.504f333f9de6484597d89b3754a8p-4 : inexact
+= rsqrt tonearest binary128 0x2p+0 : 0xb.504f333f9de6484597d89b3754a8p-4 : inexact
+= rsqrt towardzero binary128 0x2p+0 : 0xb.504f333f9de6484597d89b3754a8p-4 : inexact
+= rsqrt upward binary128 0x2p+0 : 0xb.504f333f9de6484597d89b3754bp-4 : inexact
+= rsqrt downward ibm128 0x2p+0 : 0xb.504f333f9de6484597d89b3754p-4 : inexact
+= rsqrt tonearest ibm128 0x2p+0 : 0xb.504f333f9de6484597d89b3754p-4 : inexact
+= rsqrt towardzero ibm128 0x2p+0 : 0xb.504f333f9de6484597d89b3754p-4 : inexact
+= rsqrt upward ibm128 0x2p+0 : 0xb.504f333f9de6484597d89b3758p-4 : inexact
+rsqrt 0.25
+= rsqrt downward binary32 0x4p-4 : 0x2p+0 :
+= rsqrt tonearest binary32 0x4p-4 : 0x2p+0 :
+= rsqrt towardzero binary32 0x4p-4 : 0x2p+0 :
+= rsqrt upward binary32 0x4p-4 : 0x2p+0 :
+= rsqrt downward binary64 0x4p-4 : 0x2p+0 :
+= rsqrt tonearest binary64 0x4p-4 : 0x2p+0 :
+= rsqrt towardzero binary64 0x4p-4 : 0x2p+0 :
+= rsqrt upward binary64 0x4p-4 : 0x2p+0 :
+= rsqrt downward intel9