Revert "update skvx scalar-fallback strategy"
Revert "update skvx scalar-fallback strategy"

This reverts commit 4985db413d3ee27b944936c71c0cd04740cd28da.

Reason for revert:

../../third_party/skia/include/private/SkVx.h:491:14: runtime error: control flow integrity check for type 'float (float)' failed during indirect function call
(/lib/x86_64-linux-gnu/libm.so.6+0x36460): note: (unknown) defined here
../../third_party/skia/include/private/SkVx.h:491:14: note: check failed in /b/s/w/ir/out/Release/viz_unittests, destination function located in /lib/x86_64-linux-gnu/libm.so.6
    #0 0x55e964d3c1f9 in skvx::Vec<4, float> skvx::map_<4, float, float, 0ul, 1ul, 2ul, 3ul>(skvx::Vec<4, float> const&, float (*)(float), std::__1::integer_sequence<unsigned long, 0ul, 1ul, 2ul, 3ul>) ./../../third_party/skia/include/private/SkVx.h:491

I don't understand what's wrong here, but I have a better map() coming up anyway.

Original change's description:
> update skvx scalar-fallback strategy
> 
> Turns out Clang's a lot better at auto-vectorizing "obvious" scalar code
> into obvious vector code when it's written out the long way, e.g.
> 
>      F32x4 x = ...;
>      x = { sqrtf(x[0]), sqrtf(x[1]), sqrtf(x[2]), sqrtf(x[3]) };
> 
> vectorizes into sqrtps a lot more reliably than our recurse-onto-scalars
> strategy, and also better than the other naive approach,
> 
>      F32x4 x = ...;
>      for (int i = 0; i < 4; i++) { x[i] = sqrtf(x[i]); }
> 
> So here I've added a map(V, fn) -> V' using C++14 tricks to let the
> compiler handle the expansion of x = { fn(x[0]), fn(x[1]), ...
> fn(x[N-1]) } for any N, and implemented most skvx scalar fallback code
> using that.
> 
> With these now vectorizing well at any N, we can remove any
> specializations we'd written for particular N, really tidying up.
> 
> Over in the SkVM interpreter, this is a big improvement for ceil and
> floor, which were being done 2 floats at a time instead of 8.  They're
> now slimmed way down to
> 
>    shlq       $6, %r13
>    vroundps   $K, (%r12,%r13), %ymm0
>    vroundps   $K, 32(%r12,%r13), %ymm1
>    jmp        ...
> 
> where K is 9 or 10 depending on the op.
> 
> I haven't found a scalar function that Clang will vectorize to vcvtps2pd
> (the rounding one, not truncating vcvttps2pd), so I've kept lrint()
> written the long way, updated to the style I've been using lately with
> specializations inline.
> 
> Change-Id: Ia97abe3c876008228bf62b1daacd6f6140408fc4
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317375
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>

TBR=14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com,herb@google.com

Change-Id: I27b5eff3328bf2ddf7063ee0dee14a378ff23b89
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317546
Reviewed-by: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>
Commit-Queue: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>

aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia