tree 48907301f4dde40b283008becfba596585abc8f0
parent c7d9aac7182fec29979a86e544d44e441a76cc0b
author Hiroshi Yamauchi <yamauchi@google.com> 1536081553 +0000
committer Hiroshi Yamauchi <yamauchi@google.com> 1536081553 +0000

[PGO] Control Height Reduction

Summary:
Control height reduction merges conditional blocks of code and reduces the
number of conditional branches in the hot path based on profiles.

if (hot_cond1) { // Likely true.
  do_stg_hot1();
}
if (hot_cond2) { // Likely true.
  do_stg_hot2();
}

->

if (hot_cond1 && hot_cond2) { // Hot path.
  do_stg_hot1();
  do_stg_hot2();
} else { // Cold path.
  if (hot_cond1) {
    do_stg_hot1();
  }
  if (hot_cond2) {
    do_stg_hot2();
  }
}

This speeds up some internal benchmarks up to ~30%.

Reviewers: davidxl

Reviewed By: davidxl

Subscribers: xbolva00, dmgreen, mehdi_amini, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D50591

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341386 91177308-0d34-0410-b5e6-96231b3b80d8