[CodeGen] Add an option to skip extTSP BB placement for huge functions. (#99310)

The extTSP-based basic block layout algorithm improves the performance
of the generated code, but unfortunately it has a super-linear time
complexity. This leads to extremely long compilation times for certain
relatively rare kinds of autogenerated code.

This patch adds an `-mllvm` flag to optionally restrict extTSP only to
functions smaller than a specified threshold. While commit
bcdc0477319a26fd8dcdde5ace3bdd6743599f44 added a knob to to limit the
maximum chain size, it's still possible that for certain huge functions
the number of chains is very large, leading to a quadratic behaviour in
ExtTSPImpl::mergeChainPairs.

0 files changed, 0 insertions, 0 deletions