math: Remove the SVID error handling from atan2f

It improves latency for about 3-6% and throughput for about 5-12%. Tested on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
2026-10-24 01:33:52 +03:00 · 2025-11-04 13:20:00 -03:00
parent a5cc3018f3
commit 7ec8eb5676
29 changed files with 62 additions and 7 deletions
--- a/math/Versions
+++ b/math/Versions
@@ -691,6 +691,7 @@ libm {
    acosf;
    acoshf;
    asinf;
+    atan2f;
    atanhf;
    coshf;
    j0f;
--- a/math/w_atan2f_compat.c
+++ b/math/w_atan2f_compat.c
@@ -26,9 +26,9 @@
 #include <libm-alias-float.h>


-#if LIBM_SVID_COMPAT
+#if LIBM_SVID_COMPAT && SHLIB_COMPAT (libm, GLIBC_2_0, GLIBC_2_43)
 float
-__atan2f (float y, float x)
+__atan2_compatf (float y, float x)
 {
  float z;

@@ -40,5 +40,10 @@ __atan2f (float y, float x)
    __set_errno (ERANGE);
  return z;
 }
-libm_alias_float (__atan2, atan2)
+# ifdef NO_COMPAT_NEEDED
+strong_alias (__atan2_compatf, __atan2f)
+libm_alias_float (__atan2_compat, atan2)
+# else
+compat_symbol (libm, __atan2_compatf, atan2f, GLIBC_2_0);
+# endif
 #endif
--- a/sysdeps/ieee754/flt-32/e_atan2f.c
+++ b/sysdeps/ieee754/flt-32/e_atan2f.c
@@ -3,7 +3,7 @@
 Copyright (c) 2022-2024 Alexei Sibidanov and Paul Zimmermann.

 The original version of this file was copied from the CORE-MATH
-project (file src/binary32/atan2/atan2f.c, revision 7835c5d).
+project (file src/binary32/atan2/atan2f.c, revision 9b28a4a).

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -28,6 +28,8 @@ SOFTWARE.
 #include <math.h>
 #include <stdint.h>
 #include <libm-alias-finite.h>
+#include <libm-alias-float.h>
+#include <math-svid-compat.h>
 #include "math_config.h"

 static inline double
@@ -85,11 +87,15 @@ cr_atan2f_tiny (float y, float x)
      else
 	t -= 1;
    }
-  return asdouble (t);
+  double r = asdouble (t);
+  float rf = r;
+  if (__glibc_unlikely (rf == 0.0f))
+    return __math_uflowf (t >> 63);
+  return rf;
 }

 float
-__ieee754_atan2f (float y, float x)
+__atan2f (float y, float x)
 {
  static const double cn[] =
    {
@@ -269,6 +275,16 @@ __ieee754_atan2f (float y, float x)
 	}
      r = th + tm;
    }
-  return r;
+  float rf = r;
+  if (__glibc_unlikely (rf == 0.0f))
+    return __math_uflowf (asuint (rf) >> 1);
+  return rf;
 }
+strong_alias (__atan2f, __ieee754_atan2f)
+#if LIBM_SVID_COMPAT
+versioned_symbol (libm, __atan2f, atan2f, GLIBC_2_43);
+libm_alias_float_other (__atan2, atan2)
+#else
+libm_alias_float (__atan2, atan2)
+#endif
 libm_alias_finite (__ieee754_atan2f, __atan2f)
--- a/sysdeps/ieee754/flt-32/w_atan2f.c
+++ b/sysdeps/ieee754/flt-32/w_atan2f.c
@@ -0,0 +1 @@
+/* Not needed.  */
--- a/sysdeps/m68k/m680x0/fpu/w_atan2f_compat.c
+++ b/sysdeps/m68k/m680x0/fpu/w_atan2f_compat.c
@@ -0,0 +1,8 @@
+/* m68k provides an optimized __ieee754_atan2f.  */
+#ifdef SHARED
+# define NO_COMPAT_NEEDED 1
+# include <math/w_atan2f_compat.c>
+#else
+# include <math-type-macros-float.h>
+# include <w_atan2_template.c>
+#endif
--- a/sysdeps/mach/hurd/i386/libm.abilist
+++ b/sysdeps/mach/hurd/i386/libm.abilist
@@ -1320,6 +1320,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 fmod F
--- a/sysdeps/unix/sysv/linux/aarch64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libm.abilist
@@ -1288,6 +1288,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/alpha/libm.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libm.abilist
@@ -1447,6 +1447,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/arm/be/libm.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/arm/le/libm.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/hppa/libm.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/i386/libm.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libm.abilist
@@ -1327,6 +1327,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 fmod F
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/microblaze/be/libm.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/be/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/microblaze/le/libm.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/le/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist
@@ -1288,6 +1288,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist
@@ -1100,6 +1100,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist
@@ -1099,6 +1099,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libm.abilist
@@ -1093,6 +1093,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libm.abilist
@@ -1477,6 +1477,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist
@@ -1391,6 +1391,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist
@@ -1391,6 +1391,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/sh/be/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/sh/le/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/libm.abilist
@@ -953,6 +953,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist
@@ -1398,6 +1398,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist
@@ -1288,6 +1288,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist
@@ -1321,6 +1321,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist
@@ -1321,6 +1321,7 @@ GLIBC_2.42 rsqrtl F
 GLIBC_2.43 acosf F
 GLIBC_2.43 acoshf F
 GLIBC_2.43 asinf F
+GLIBC_2.43 atan2f F
 GLIBC_2.43 atanhf F
 GLIBC_2.43 coshf F
 GLIBC_2.43 j0f F