Re:Firefox 64 built with GCC and Clang
by nkurz on Sunday December 16, 2018 @10:55AM
(#18693557)
Does GCC introduce multiversioned AVX functions on its own initiative?
Yes, this seems like one reasonable approach. The current approach of compiling to a "least common denominator" and then updating this denominator every decade or so seems insufficient. Instead of interpreting the absence of a "-march=" flag to mean optimize for nothing, maybe it can mean that multiple optimizations are automatically compiled and the appropriate one is selected at runtime. Alternatively, maybe we need to move away from the idea of compiling a single binary that runs on all platforms, and encourage greater use of platform specific compilations.
Re:Firefox 64 built with GCC and Clang
by hubicka on Sunday December 16, 2018 @11:35AM
(#18693757)
You need to explicitly ask for it via attribute, no automatic multiversioning is done (yet) and it would be more for -Ofast than usual -O2 builds I guess.
Yes, this seems like one reasonable approach. The current approach of compiling to a "least common denominator" and then updating this denominator every decade or so seems insufficient. Instead of interpreting the absence of a "-march=" flag to mean optimize for nothing, maybe it can mean that multiple optimizations are automatically compiled and the appropriate one is selected at runtime. Alternatively, maybe we need to move away from the idea of compiling a single binary that runs on all platforms, and encourage greater use of platform specific compilations.