See "SXTB, SXTH, SXTW" in the exploration tools

SXTW: Signed word extend (predicated)

SXTW Zd.D, Pg/M, Zn.D (SVE (SME

svint64_t svextw[_s64]_m(svint64_t inactive, svbool_t pg, svint64_t op)

128-bit SVE

For each 64-bit value integer set (2) to ( (1) & 0x7FFFFFFF ) − ( (1) & 0x80000000 ). This takes the low 32-bits of (1), and sign-extends it to 64-bit.

256-bit SVE

For each 64-bit value integer set (2) to ( (1) & 0x7FFFFFFF ) − ( (1) & 0x80000000 ). This takes the low 32-bits of (1), and sign-extends it to 64-bit.

512-bit SVE

For each 64-bit value integer set (2) to ( (1) & 0x7FFFFFFF ) − ( (1) & 0x80000000 ). This takes the low 32-bits of (1), and sign-extends it to 64-bit.

Larger sizes

1024-bit SVE

For each 64-bit value integer set (2) to ( (1) & 0x7FFFFFFF ) − ( (1) & 0x80000000 ). This takes the low 32-bits of (1), and sign-extends it to 64-bit.

2048-bit SVE

For each 64-bit value integer set (2) to ( (1) & 0x7FFFFFFF ) − ( (1) & 0x80000000 ). This takes the low 32-bits of (1), and sign-extends it to 64-bit.

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Inspired by and based on the x86/x64 SIMD Instruction List by Daytime.