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A comment on AMD's Zen 6 Family: Feeding the Beast.

Re:AMD's Zen 6 Family: Feeding the Beast by Aardwolf on Tuesday November 10, 2026 @01:24PM (#50444152)
> AMD has reduced the number of integer multiply units from three to two, with PDEP and PEXT throughput also falling from three instructions per cycle to two.

Are PDEP and PEXT using the same (parts of) circuits as multiply (they are very different operations...), or are this just two independent drops of circuitry and the wording is just a bit unclear?

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Re:AMD's Zen 6 Family: Feeding the Beast by adrian_b on Tuesday November 10, 2026 @02:36PM (#50445189)
They are unlikely to share circuits with the multipliers, but the 2 of the 6 execution units that include multipliers must be identical, to simplify layout, and the PDEP/PEXT circuits are allocated to these 2 units, like the multipliers.
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Re:AMD's Zen 6 Family: Feeding the Beast by jandrewrogers on Tuesday November 10, 2026 @04:29PM (#50446565)
IIRC, PDEP/PEXT are generalizations of shifter networks.
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Re:AMD's Zen 6 Family: Feeding the Beast by seastarer on Tuesday November 10, 2026 @05:41PM (#50447329)
A multiplier also contains a generalized shifter network.

Multiplying by 2^n = shift by n.

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