On Sun, Nov 26, 2017 at 01:40:06PM +0000, Stuart Henderson wrote: > On 2017/11/26 14:00, Sebastien Marie wrote: > > Hi, > > > > The following diff makes i386 to be compiled without --enable-rust-simd. > > simd is "Single instruction, multiple data" (aka MMX, SSE, SSE2...). > > > > rustc when compiled with external LLVM doesn't export target_features as > > compilation variable, making firefox building to fail. > > > > I workarounded the problem on amd64 by manually exported SSE2 symbol > > (always present on amd64). But for i386, same hack isn't possible (as > > not all i386 processors have such extensions). So it is preferable to > > not enable simd on i386. > > > > I tested the diff with rustc 1.22.1 and firefox still build well (but no > > runtime test). > > Is it actually needed? I can't imagine anything that can actually *run* > firefox (RAM-wise) that doesn't at least have SSE. > > Due to the serious lack of registers on i386 (especially with PIE) I think > it needs all the help it can get...
Afaict we cant just say 'i386 has sse2' within rust build config (or it'd need the same export as is done on amd64 ?), but i'd personally be fine with it - firefox on my atom n270 is unusable and that's my only i386, i doubt anyone is running^Wtrying to run firefox on anything slower... Landry
