[PATCH] D28593: Update loop branch_weight metadata after loop rotation.

[Xin Tong via Phabricator via llvm-commits]

trentxintong added a comment.

I ran C/C++ benchmarks in CPU2006 with the current state of the patch (baseline is without the metadata adjustment, negative percent means the benchmark runs slower or code size becomes smaller after the patch.  It seems the the regressions in 429 and 444 are real. And we also have a code size reduction of -2.41% in 401. Overall, we have more performance regressions after we adjust the metadata this way.

  Benchmark	Perf		CodeSize
  400		-0.22%		0.00%
  401		0.76%		-2.41%
  403		-0.51%		0.07%
  429		-2.09%		0.32%
  445		0.64%		-0.08%
  456		-0.29%		0.01%
  458		0.00%		-0.04%
  462		-0.15%		0.00%
  464		0.16%		0.00%
  471		-0.38%		-0.02%
  473		0.00%		-0.21%
  483		-0.40%		-0.04%
  433		0.73%		0.03%
  444		-2.15%		-0.26%
  447		-0.17%		-0.06%
  450		0.00%		-0.05%
  453		0.38%		-0.01%
  470		0.12%		0.00%
  482		0.18%		0.14%


https://reviews.llvm.org/D28593