It removes the wrapper by moving the error/EDOM handling to an
out-of-line implementation (__math_invalidf_i/__math_invalidf_li).
Also, __glibc_unlikely is used on errors case since it helps
code generation on recent gcc.
The code now builds to with gcc-14 on aarch64:
0000000000000000 <__ilogbf>:
0: 1e260000 fmov w0, s0
4: d3577801 ubfx x1, x0, #23, #8
8: 340000e1 cbz w1, 24 <__ilogbf+0x24>
c: 5101fc20 sub w0, w1, #0x7f
10: 7103fc3f cmp w1, #0xff
14: 54000040 b.eq 1c <__ilogbf+0x1c> // b.none
18: d65f03c0 ret
1c: 12b00000 mov w0, #0x7fffffff // #2147483647
20: 14000000 b 0 <__math_invalidf_i>
24: 53175800 lsl w0, w0, #9
28: 340000a0 cbz w0, 3c <__ilogbf+0x3c>
2c: 5ac01000 clz w0, w0
30: 12800fc1 mov w1, #0xffffff81 // #-127
34: 4b000020 sub w0, w1, w0
38: d65f03c0 ret
3c: 320107e0 mov w0, #0x80000001 // #-2147483647
40: 14000000 b 0 <__math_invalidf_i>
Some ABI requires additional adjustments:
* i386 and m68k requires to use the template version, since
both provide __ieee754_ilogb implementatations.
* loongarch uses a custom implementation as well.
* powerpc64le also has a custom implementation for POWER9, which
is also used for float and float128 version. The generic
e_ilogb.c implementation is moved on powerpc to keep the
current code as-is.
Checked on aarch64-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>