Update ExprTk

[ArashPartow]

• Moved submodule to release branch
• Release notes: https://www.partow.net/programming/exprtk/exprtk_release_notes_v0.0.3.txt

[Rossmaxx]

@gnudles if you don't mind, can you brief us about the effects of updating the submodule. I'm asking you because the rest of us are clueless about the xpressive plugin infrastructure.

[gnudles]

It is the under the hood engine that evaluates the expressions

[messmerd]

Are there any plans to try to cut down on the Xpressive/exprtk binary size?

In this PR it is 66.2 MB uncompressed on Linux, while on master it is currently 70.9 MB. That's a little better, but it's still by far the largest single file in the installation after the lmms executable itself. Plus it takes longer than the other plugins to compile.

[ArashPartow]

@messmerd a large proportion of that would be symbols et al that could be safely removed at least on Linux builds using the strip -s libxpressive.so command.

-rwxr-xr-x 1 66209040 Nov 20 10:05 libxpressive.so
-rwxr-xr-x 1 10554912 Nov 20 10:06 libxpressive_stripped.so

Might also want to do some analysis with bloaty

---

wrt to compilation times. It is not compilation that is slow, but rather linking. It seems that LMMS is using ye-olde ld to link. My suggestion would be to move to gold or even better yet mold or lld.

The change to the CMakeLists.txt should look something like this for linux builds:

set(CMAKE_EXE_LINKER_FLAGS -fuse-ld=gold)

Building the ExprTk test suite without and with gold:

time g++-13 -pedantic-errors -Wall -Wextra -Werror -std=c++23 -O2 -DNDEBUG -o exprtk_test exprtk_test.cpp -L/usr/lib -lstdc++

real    1m39.624s
user    1m37.630s
sys     0m1.911s


time g++-13 -pedantic-errors -Wall -Wextra -Werror -std=c++23 -O2 -DNDEBUG -o exprtk_test exprtk_test.cpp -L/usr/lib -lstdc++ -Wl,-fuse-ld=gold

real    0m42.258s
user    0m40.412s
sys     0m1.750s

[messmerd]

That's great to see! I'll look into stripping the binaries and using lld or mold.

[gnudles]

It's worth checking why the debugging symbols are there in first place.