[PATCH] D100818: [lld-macho] Implement branch-range-extension thunks

Mon May 17 12:08:46 PDT 2021

thakis added a comment.

This seems to slow down (x86) links by 2.8% (using the repro at https://bugs.llvm.org/show_bug.cgi?id=48657#c0 , and `~/src/hack/bench.py -n10 -o at_thunk ../out/gn/bin/ld64.lld @response.txt` , with https://github.com/nico/hack/blob/master/bench.py; I built lld right before this rev (`git checkout 93c8559baf551a7a30ab17654569ac5ac92986f4^`) and at this rev (`git checkout 93c8559baf551a7a30ab17654569ac5ac92986f4`).

  `
  chromium_framework % ministat at*thunk
  x at_before_thunk
  + at_thunk
      N           Min           Max        Median           Avg        Stddev
  x  10     3.9163771     3.9668748     3.9350698     3.9360609   0.016793477
  +  10      3.954447     4.2126601     4.0607598     4.0460292   0.072968429

Is that expected? Is this something you can repro?

Also, re patch description: Would be nice if the commit message had said _why_ a different algorithm was chosen :)

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100818/new/

https://reviews.llvm.org/D100818