Add -fno-ipa-cp-clone on GCC

mirror of https://github.com/official-stockfish/Stockfish.git synced 2026-07-23 05:07:14 +00:00

Passed non-regression STC at
tests.stockfishchess.org/tests/view/69c9b8c3a54395a761335044 (set to
gainer bounds, *mea culpa*)

There's a major performance penalty when compiling the fish with GCC 16.
@Torom 's measurements (similar to mine, but more precise):

```
GCC 15 (master) vs. 16 (master)
sf_base =  2549174 +/-   2984 (95%)
sf_test =  2435456 +/-   2239 (95%)
diff    =  -113718 +/-   3599 (95%)
speedup = -4.46100% +/- 0.141% (95%)

GCC 15 (master) vs. 16 (patch)
sf_base =  2544107 +/-   3091 (95%)
sf_test =  2568837 +/-   3164 (95%)
diff    =    24729 +/-   4359 (95%)
speedup = 0.97204% +/- 0.171% (95%)
```

Based on looking at the disassembly + profiling data of the builds, the
root cause appears to be overly aggressive code duplication from
constant propagation of various functions especially in `search.cpp`.
The worst offender is `Worker::search`, which I think is being cloned
and optimized based on the value of `cutNode`. `perf stat` indicates
that the instruction cache miss rate goes up by ~50% on the GCC 16
build.

closes https://github.com/official-stockfish/Stockfish/pull/6691

No functional change

This commit is contained in:

anematode

2026-04-02 20:32:34 +02:00

committed by

Disservin

parent 347fcaa392

commit c41c9bb973

1 changed files with 1 additions and 1 deletions

									
										src/Makefile
									
		+1
		-1
	
												View File
												
				@@ -451,7 +451,7 @@ endif

				ifeq ($(COMP),gcc)

					comp=gcc

					CXX=g++

					CXXFLAGS += -pedantic -Wextra -Wshadow -Wmissing-declarations

					CXXFLAGS += -pedantic -Wextra -Wshadow -Wmissing-declarations -fno-ipa-cp-clone

					ifeq ($(arch),$(filter $(arch),armv7 armv8 riscv64))

						ifeq ($(OS),Android)