Extend unrolling preferences to allow more aggressive unrolling of
search loops with 2 exits, building on the TTI hook added in
ad9da92cf6.
In combination with
eac23a5b97
this enables unrolling loops like
std::find, which can improve performance significantly (+15% end-to-end
on a workload that makes heavy use of std::find). It increase the total
number of unrolled loops by ~2.5% across a very large corpus of
workloads.
For SPEC2017, +1.6% more loops are unrolled and the following workloads
increase in size (`__text`):
workload base patch
500.perlbench_r 1682884.00 1694104.00 0.7%
523.xalancbmk_r 3001716.00 3003832.00 0.1%
PR: https://github.com/llvm/llvm-project/pull/124751
46a13a5b17