Make -linkonce-templates less aggressive by default & add -linkonce-templates-aggressive #3924
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Runtimes and peak working sets (best-of-3) of
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…emplates-aggressive Make -linkonce-templates *not* tamper with the general template emission algorithm anymore (so on top of default non-allinst or -allinst modes), and keep those tweaks as experimental -linkonce-templates-aggressive. Compiling the druntime/Phobos unittests is only marginally slowed down compared to the more aggressive variant (~1.5% for debug, ~2.5% for release). It does show some rough 10% increase in required memory, but that's in line with non-linkonce-templates. The more aggressive variant has the advantage of skipping needsCodegen() and potentially codegen'ing less symbols. The problem is that if an instantiated symbol isn't explicitly referenced, for instance a CRT ctor, it might not be codegen'd at all.
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Make
-linkonce-templatesnot tamper with the general template emission algorithm anymore (so on top of default non-allinst or-allinstmodes), and keep those tweaks as experimental-linkonce-templates-aggressive.Compiling the druntime/Phobos unittests is only marginally slowed down compared to the more aggressive variant (~1.5% for debug, ~2.5% for release). It does show some rough 10% increase in required memory, but that's in line with non-linkonce-templates.
The more aggressive variant has the advantage of skipping
needsCodegen()and potentially codegen'ing less symbols. The problem is that if an instantiated symbol isn't explicitly referenced, for instance a CRT ctor, it might not be codegen'd at all.