Developer Guide and Reference

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_mm256_zeroupper

Zeroes the upper bits of the YMM registers. The corresponding Intel® AVX instruction is
VZEROUPPER
.

Syntax

extern void _mm256_zeroupper(void);
Arguments
None
Description
Zeroes the upper 128 bits of all
YMM
registers. The lower 128 bits that correspond to the
XMM
registers are left unmodified.
This intrinsic is useful to clear the upper bits of the
YMM
registers when transitioning between Intel® Advanced Vector Extensions (Intel® AVX) instructions and legacy Intel® Supplemental SIMD Extensions (Intel® SSE) instructions. There is no transition penalty if an application clears the upper bits of all
YMM
registers (sets to ‘0’) via
VZEROUPPER
, the corresponding instruction for this intrinsic, before transitioning between Intel® Advanced Vector Extensions (Intel® AVX) instructions and legacy Intel® Supplemental SIMD Extensions (Intel® SSE) instructions.
Returns
Result of the operation.

Product and Performance Information