[llvm-dev] An option switching LSR to choose solution with minimum instructions

Evgeny Stupachenko via llvm-dev llvm-dev at lists.llvm.org
Tue Feb 14 12:44:36 PST 2017

Hi All,

A new option for LSR "-lsr-insns-cost" was introduced in the patch
Basically it set instruction count as priority number one for
solutions with low register use.
This lead to smaller loops in most cases.

The goal is to enable the option by default for x86.
Could you please check your benchmarks to see if there are gains/loses
and report this here?

That I have for now is:
177.mesa on -O2 +3%
256.bzip2 on -Ofast -flto +1.5%
and overall good improvements for x86.
The only regression is on linpack test 3% on HSW, however it differs
on other CPUs (say for Atoms it is 3% gain).


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