[PATCH][lld] ELF/AArch64: Add support for checking for ABS32 overflow

[Tim Northover]

> +/// \brief Check X is in the interval (-2^(bits-1), 2^bits]
> +bool withinSignedUnsignedRange(int64_t X, int bits) {

This should probably be a static function.

> +  if (X < -(1L << (bits - 1)) || X >= (1L << bits))

I think long is only 32-bits on Windows, so we should use 1LL (and
assert that Bits < 64, just in case someone tries to extend its use
carelessly later).

Otherwise, it looks reasonable to me, though I'm not really much of an
lld expert.

Tim.