[all-commits] [llvm/llvm-project] 472515: [SimplifyCFG] Cost required selects

[Sam Parker via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 47251582f5c2ac5962f52bc6ddd3d612c56ab83d
      https://github.com/llvm/llvm-project/commit/47251582f5c2ac5962f52bc6ddd3d612c56ab83d
  Author: Sam Parker <sam.parker at arm.com>
  Date:   2020-08-21 (Fri, 21 Aug 2020)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyCFG.cpp
    M llvm/test/Transforms/SimplifyCFG/ARM/select-costs.ll

  Log Message:
  -----------
  [SimplifyCFG] Cost required selects

Before we speculatively execute a basic block, query the cost of
inserting the necessary select instructions against the phi folding
threshold. For non-trivial insertions, a more accurate decision can
probably be made during machine if-conversion. With minsize we query
the CodeSize cost, otherwise we use SizeAndLatency.

Differential Revision: https://reviews.llvm.org/D82438