On 22/07/2021 08:45, Prathamesh Kulkarni via Gcc-patches wrote:
Hi,
The attached patch removes calls to builtins from vshl_n intrinsics,
and replacing them
with left shift operator. The patch passes bootstrap+test on
arm-linux-gnueabihf.
Altho, I noticed, that the patch causes 3 extra registers to spill
using << instead
of the builtin for vshl_n.c. Could that be perhaps due to inlining of
intrinsics ?
Before patch, the shift operation was performed by call to
__builtin_neon_vshl<type> (__a, __b)
and now it's inlined to __a << __b, which might result in increased
register pressure ?
Thanks,
Prathamesh
You're missing a ChangeLog for the patch.
However, I'm not sure about this. The register shift form of VSHL
performs a right shift if the value is negative, which is UB if you
write `<<` instead.
Have I missed something here?
R.
