Enable New Pass Manager for Clang.

It's about 1% speedup for Stockfish.

Result of 100 runs
==================
base (...fish_clang12) =    1946851  +/- 3717
test (./stockfish    ) =    1967276  +/- 3408
diff                   =     +20425  +/- 2438

speedup        = +0.0105
P(speedup > 0) =  1.0000

Thanks to David Major for making me aware of this part
of LLVM development.

closes https://github.com/official-stockfish/Stockfish/pull/3346

No functional change

diff --git a/src/Makefile b/src/Makefile
index 827ce6bb9d838930708ab6542ce04b89c411e014..1ff03f8391acca25bc4e3c5af9938d3408aa062d 100644 (file)
--- a/src/Makefile
+++ b/src/Makefile
@@ -481,6 +481,10 @@ ifeq ($(optimize),yes)
                        CXXFLAGS += -mdynamic-no-pic
                endif
        endif
                        CXXFLAGS += -mdynamic-no-pic
                endif
        endif

+
+       ifeq ($(comp),clang)
+               CXXFLAGS += -fexperimental-new-pass-manager
+       endif

 endif
 
 ### 3.4 Bits
 endif
 
 ### 3.4 Bits