Vanilla Firefox build (clang): _GLOBAL__sub_I_Unified_cpp_js_src_gc1.cpp is 6031 bytes of code. _GLOBAL__sub_I_Unified_cpp_js_src_jit1.cpp is 9898 bytes of code. Looks like they're just initializing constant data. There are probably others around here. dmajor says: Looks like they are the `phases` array and all the `FunctionInfo`s, respectively. https://searchfox.org/mozilla-central/source/__GENERATED__/js/src/gc/StatsPhasesGenerated.cpp#72 https://searchfox.org/mozilla-central/search?q=FunctionInfo&case=false&regexp=false&path=BaselineCompiler.cpp I guess converting these to const data (if possible) would reduce binary size and reduce runtime memory usage a little bit.

While we're at it, those FunctionInfos could really use some decltype love.

(In reply to David Major [:dmajor] from comment #1) > While we're at it, those FunctionInfos could really use some decltype love. I am not sure to understand the decltype aspect. When this code got added we already had the ability to infer the type from the template parameter. The reason why we have a an explicit function pointer type was made on purpose, in order to have a local repetition of the function signature, and thus better catch signature changes, than callInfo miss-use.

Ok, so the GC tables are an easy fix. I'll post a patch. For the VMFunction issue, we can't completely get away from a runtime constructor, because we have to add each instance to the `functions` linked list. Ideally the compiler would be able to statically-populate the constant fields of the structures, leaving only the minimal work for `functions` setup -- which is exactly what I coaxed MSVC into doing in bug 905210 comment 8. But apparently clang wants to do everything by hand at runtime: mov dword ptr [xul!IonCompileScriptForBaselineInfo+0x20 (00000001`85bfc560)],1000002h mov word ptr [xul!IonCompileScriptForBaselineInfo+0x24 (00000001`85bfc564)],100h etc. I'll try to distill the repro a bit and file a bug upstream.

Comment on attachment 9024788 [details] [diff] [review] Mark [Enumerated]Array constructors as constexpr. Review of attachment 9024788 [details] [diff] [review]: ----------------------------------------------------------------- ::: mfbt/Array.h @@ +26,5 @@ > public: > Array() {} > > template <typename... Args> > + MOZ_IMPLICIT constexpr Array(Args&&... aArgs) ISTR trying this and it didn't work for some reason, but that might have been either pre-c++14 or pre-MSVC 15.7 or pre-clang-cl...if it works now, that's great!

Comment on attachment 9024789 [details] [diff] [review] Use constexpr for the GC phase tables. Review of attachment 9024789 [details] [diff] [review]: ----------------------------------------------------------------- LGTM.

Pushed by dmajor@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/79148f9b3648 Mark [Enumerated]Array constructors as constexpr. r=froydnj https://hg.mozilla.org/integration/mozilla-inbound/rev/d8bb05d82665 Use constexpr for the GC phase tables. r=jonco

https://hg.mozilla.org/mozilla-central/rev/79148f9b3648 https://hg.mozilla.org/mozilla-central/rev/d8bb05d82665