https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121419
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |bpf
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
_40 = __builtin_clz (x_39);
So LLVM inlines clz always while GCC calls out to a function if the target does
not have the optab defined.
Now the bpf backend could define an optab that expands it which is very large
to begin with:
```
w2 = w1
w2 >>= 1
w1 |= w2
w2 = w1
w2 >>= 2
w1 |= w2
w2 = w1
w2 >>= 4
w1 |= w2
w2 = w1
w2 >>= 8
w1 |= w2
w2 = w1
w2 >>= 16
w1 |= w2
w1 ^= -1
w2 = w1
w2 >>= 1
w2 &= 1431655765
w1 -= w2
w0 = w1
w0 &= 858993459
w1 >>= 2
w1 &= 858993459
w0 += w1
w1 = w0
w1 >>= 4
w0 += w1
w0 &= 252645135
w0 *= 16843009
w0 >>= 24
```
This is why GCC does not inline it if the target does not implement the optab
and has it in the libgcc.
