[llvm] r213898 - [SDAG] Introduce a combined set to the DAG combiner which tracks nodes

Wed Oct 1 07:07:01 PDT 2014

Hi guys,

> Bruno, just to be sure, can you build clang with LTO where the only difference is this change to try to confirm that this patch is responsible?

A "non-LTO -Os -g" build of 403.gcc-x86-combine.c still gives ~3%
codegen-only compile time increase. This is tested by reverting this
commit only. More info:

Pass Name, Time Share A, Time Share B, Relative Increase
DAG Combining 1, 14.90%, 17.50%, 1.1745
DAG Combining 2, 7.50%, 8.75%, 1.1667
DAG Combining after legalize types, 6.90%, 7.90%, 1.1449
X86 DAG->DAG Instruction Selection, 20.10%, 20.85%, 1.0373

-- 
Bruno Cardoso Lopes
http://www.brunocardoso.cc