When calculating the specialization bonus for a given function argument,
we recursively traverse the chain of (certain) users, accumulating the
instruction costs. Then we exponentially increase the bonus to account
for loop nests. This is problematic for two reasons: (a) the users might
not themselves be inside the loop nest, (b) if they are we are accounting
for it multiple times. Instead we should be adjusting the bonus before
traversing the user chain.
This reduces the instruction count for CTMark (newPM-O3) when Function
Specialization is enabled without actually reducing the amount of
specializations performed (geomean: -0.001% non-LTO, -0.406% LTO).
Differential Revision: https://reviews.llvm.org/D136692
It would waste time to specialize a function which would inline finally.
This patch did two things:
- Don't specialize functions which are always-inline.
- Don't spescialize functions whose lines of code are less than threshold
(100 by default).
For spec2017int, this patch could reduce the number of specialized
functions by 33%. Then the compile time didn't increase for every
benchmark.
Reviewed By: SjoerdMeijer, xbolva00, snehasish
Differential Revision: https://reviews.llvm.org/D107897
The original implementation calculating UserBonus uses operator ^, which means XOR in C++
language.
At the first glance of reviewing, I thought it should be power, my bad.
It doesn't make sense to use XOR here. So I believe it should be a
carelessness as I made.
Test Plan: check-all
Reviewed By: SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D104282
