Don't use "generic" as the target cpu

[dotdash]

By default, we use the "generic" target CPU, unfortunately on x86_64, this disables various features because "generic" is more like "generic x86". This disable things like some SSE usage and multibyte nops. On x86_64 we should use x86-64 as the minimum target cpu, not sure about other archs.

To present some arbitrary numbers:

# target cpu "generic"
$ objdump -S libsyntax-4e7c5e5c.so | grep xmm -c
25148

# target cpu "x86-64"
$ objdump -S libsyntax-4e7c5e5c.so|grep xmm  -c
83740

cc @cmr

[dotdash]

To add some slightly more interesting numbers, these are for rustc -Z no-trans libsyntax/lib.rs:

generic:

real    0m33.343s
user    0m33.156s
sys     0m0.228s

x86-64

real    0m31.824s
user    0m31.688s
sys     0m0.176s

[Gankra]

@dotdash Did your PR not resolve this?

[dotdash]

It probably did for x84_64, but I'm not sure about x86 (I guess "generic"
is like i386, which seems a bit too old a target), ARM, etc.
Am 21.01.2015 23:33 schrieb "Alexis Beingessner" notifications@github.com:

@dotdash https://github.com/dotdash Did your PR not resolve this?

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#20777 (comment).