RESOLVED FIXED 248995
[WebAssembly SIMD] Emulate 8-bit shift instructions and i8x16.popcnt on Intel 
https://bugs.webkit.org/show_bug.cgi?id=248995
Summary [WebAssembly SIMD] Emulate 8-bit shift instructions and i8x16.popcnt on Intel
David Degazio
Reported 2022-12-08 16:59:10 PST
While most other SIMD bitwise operations are tracked in https://bugs.webkit.org/show_bug.cgi?id=248639, I'm splitting off the following instructions: - i8x16.shl, i8x16.shr_s, i8x16.shr_u - i8x16.popcnt into this bug so they don't hold up the other patch. None of these instructions are supported natively on Intel, at least without AVX-512, and they also aren't easy to emulate. So they require some additional effort to implement necessary supporting instructions and figure out the best isel.
Attachments
Add attachment proposed patch, testcase, etc.
David Degazio
Comment 1 2022-12-08 17:03:14 PST
rdar://103159176
David Degazio
Comment 2 2022-12-12 10:36:08 PST
Looks like despite logical right-shift being supported for 64-bit elements, arithmetic right-shift is only supported with AVX-512 (which we really can't assume will be present). So we also need to emulate i64x2.shr_s.
David Degazio
Comment 3 2022-12-16 13:44:25 PST
Pull request: https://github.com/WebKit/WebKit/pull/7777
EWS
Comment 4 2022-12-19 12:45:57 PST
Committed 258089@main (7d8a35c36444): <https://commits.webkit.org/258089@main> Reviewed commits have been landed. Closing PR #7777 and removing active labels.
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