[PATCH] D128093: [lld-macho] Initial support for Linker Optimization Hints

[Daniel Bertalan via Phabricator via llvm-commits]

BertalanD added a comment.

> Is there measurable overhead when -ignore_optimization_hints is passed? I'm wondering about the overhead from increasing the Reloc struct size

Here are the measurements taken on a 32 vCPU Google Compute Engine instance:

  x before.txt
  + after.txt
  +------------------------------------------------------------------------------+
  |                                   x  x       x   +   +  +                    |
  |x     x x x       x x * x      ++x x++x x xxx * + +  ++  + ++   +   +x +     +|
  |              |________________A___M_|__________|__A__M__________|            |
  +------------------------------------------------------------------------------+
      N           Min           Max        Median           Avg        Stddev
  x  20     11.418539     11.729058     11.576444     11.557527   0.076616973
  +  20      11.51961      11.76536     11.661534     11.649677   0.063851569
  Difference at 95.0% confidence
  	0.0921498 +/- 0.0451383
  	0.797314% +/- 0.390554%
  	(Student's t, pooled s = 0.0705237)

With `--threads=1`, it says "No difference proven at 95.0% confidence".
I'll check if there are any opportunities to pack the `InputSection` class a bit better.


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https://reviews.llvm.org/D128093