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authorChristian Krinitsin <mail@krinitsin.com>2025-07-17 09:10:43 +0200
committerChristian Krinitsin <mail@krinitsin.com>2025-07-17 09:10:43 +0200
commitf2ec263023649e596c5076df32c2d328bc9393d2 (patch)
tree5dd86caab46e552bd2e62bf9c4fb1a7504a44db4 /results/scraper/fex/4213
parent63d2e9d409831aa8582787234cae4741847504b7 (diff)
downloadqemu-analysis-f2ec263023649e596c5076df32c2d328bc9393d2.tar.gz
qemu-analysis-f2ec263023649e596c5076df32c2d328bc9393d2.zip
add downloaded fex bug-reports HEAD main
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+{v,}ptest can be made more efficient with SVE
+{v,}ptest is a bit of a weird family of instructions because it sets ZF and CF depending on if the full mask, or negated mask is all zeroes respectively. This is a bit of a faff with ASIMD since it doesn't match semantically, and AVX just adds even more instructions to it.

+

+With SVE they added the new `CMP<cc>` instructions which set both a predicate register and the NZCV flags. This can reduce the number of instructions that {v,}ptest requires by quite a bit.

+

+Likely worth implementing.
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