feat: optimize Hermes for speed rather than size in Android

[kewde]

Summary:

The Release flag is being used for iOS but interestingly, on Android it is optimized for size.
I haven't done any performance testing but from my experience within our react native application, we have noticed that Hermes on iOS devices generally runs much faster than comparable Android devices.

We'll be conducting performance testing on our hermes fork & inside our own application soon but I don't have numbers yet.
LTO was also recently enabled in #50529 which may also affect performance which makes estimating the isolated performance impact of this PR alone a bit more complicated.

Size changes:

• hermes-release.aar went from 6.9 MB to 9.2 MB on our fork.
• hermes-release.aar/jni/{arch}/libhermes.so
  • arm64-v8a: 1.8 MB -> 2.3 MB
  • armeabi-v7a: 1.3 MB -> 1.8 MB
  • x86: 2.2MB -> 3.2MB
  • x86_64: 2MB -> 2.7 MB

Changelog:

[ANDROID] [CHANGED] - build hermes release version optimized for speed rather than size

Test Plan:

• Does the libhermes dynamic library change a lot in size?
• Is the performance difference worth it?

[kewde]

We've profiled a production release of these changes on our application and haven't seen statistically significant performance improvements with this release flag change.
It's worth noting, we're on a pretty old version of hermes & compiling with Clang 12 - you may see different results with the latest hermes & latest compilers.

[cortinico]

We've profiled a production release of these changes on our application and haven't seen statistically significant performance improvements with this release flag change.
It's worth noting, we're on a pretty old version of hermes & compiling with Clang 12 - you may see different results with the latest hermes & latest compilers.

Were you able to profile against main as that should provide the most valuable metrics here

[kewde]

@cortinico

I'll try and repeat the experiment for 0.78 - which is only 85 commits behind of master of hermes, that might be more representative of the latest state of hermes. The hermes version that we are using was about ~1500 commits behind master :|

[cortinico]

The Release flag is being used for iOS but interestingly, on Android it is optimized for size.

Also @cipolleschi just pointed out how Android and iOS are actually aligned:

react-native/packages/react-native/sdks/hermes-engine/utils/build-apple-framework.sh

Lines 77 to 83 in 1fb04e2

	if [[ $BUILD_TYPE == "Debug" ]]; then
	# JS developers aren't VM developers.
	# Therefore we're passing as build type Release, to provide a faster build.
	cmake_build_type="Release"
	else
	cmake_build_type="MinSizeRel"
	fi

[kewde]

@cortinico

Good call out, I was looking at upstream hermes - I actually wasn't aware that react native shipped a copy of these

upstream definitely has Release set insize of MinSizeRel
https://github.com/facebook/hermes/blob/11c154bc365447648fa56fdd67a1c142034b85a6/utils/build-apple-framework.sh#L7-L11

[cortinico]

Good call out, I was looking at upstream hermes - I actually wasn't aware that react native shipped a copy of these

Yeah the React Native ones are the relevant one as we're the integrator of Hermes in this particular instance