[glibc] aarch64: Improve special-case handling in AdvSIMD double-precision libmvec routines

[glibc] aarch64: Improve special-case handling in AdvSIMD double-precision libmvec routines

[Szabolcs Nagy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=7b12776584c51dbecb1033e107f6b9f45de47a1b

commit 7b12776584c51dbecb1033e107f6b9f45de47a1b
Author: Joe Ramsay <Joe.Ramsay@arm.com>
Date:   Mon Nov 27 17:02:55 2023 +0000

    aarch64: Improve special-case handling in AdvSIMD double-precision libmvec routines
    
    Avoids emitting many saves/restores of vector registers, reduces the
    amount of code generated around the scalar fallback.

Diff:
---
 sysdeps/aarch64/fpu/v_math.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/sysdeps/aarch64/fpu/v_math.h b/sysdeps/aarch64/fpu/v_math.h
index cfc87f8dd0..d286eb81b3 100644
--- a/sysdeps/aarch64/fpu/v_math.h
+++ b/sysdeps/aarch64/fpu/v_math.h
@@ -137,7 +137,13 @@ v_lookup_u64 (const uint64_t *tab, uint64x2_t idx)
 static inline float64x2_t
 v_call_f64 (double (*f) (double), float64x2_t x, float64x2_t y, uint64x2_t p)
 {
-  return (float64x2_t){ p[0] ? f (x[0]) : y[0], p[1] ? f (x[1]) : y[1] };
+  double p1 = p[1];
+  double x1 = x[1];
+  if (__glibc_likely (p[0]))
+    y[0] = f (x[0]);
+  if (__glibc_likely (p1))
+    y[1] = f (x1);
+  return y;
 }
 static inline float64x2_t
 v_call2_f64 (double (*f) (double, double), float64x2_t x1, float64x2_t x2,