PCMPEQW

/ VPCMPEQW

Compare equal 16-bit elements

Produce an all-ones 16-bit mask for each true comparison, otherwise zero.

SSE216-bit unsigned elements

Similar operations on Arm64:CMEQvceqq_u16

Form	Bits	Requires	Encoding
`PCMPEQW xmm1, xmm2`	128	SSE2	`66 0F 75 /r`
`VPCMPEQW xmm1, xmm2, xmm3`	128	AVX	`VEX.L0.66.0F.WIG 75 /r`
`VPCMPEQW ymm1, ymm2, ymm3`	256	AVX2	`VEX.L1.66.0F.WIG 75 /r`

128 bits · 8 × 16-bit elements

Operation#

Pseudo-C · selected form

dst[i] = (a[i] == b[i]) ? 65535 : 0

Simplified pseudocode for the selected form.

What to watch for

Equality compares bit patterns. Output masks do not update integer flags.

Corresponding intrinsics#

C / C++ · selected form

_mm_cmpeq_epi16

Open example

__m128i _mm_cmpeq_epi16(__m128i a, __m128i b)

#include <emmintrin.h>SSE2

Documented instruction mapping; a compiler may use an equivalent encoding or optimize the operation away.

Documented mapping

PCMPEQW xmm, xmm

Architectural details#

Flags: RFLAGS unchanged.
Destination: Writes the low 128 bits; upper vector-register bits are preserved.
Encoding: 66 0F 75 /r
Operands: xmm1read / write · 128 bits (8 × 16) · unsigned
xmm2read · 128 bits (8 × 16) · unsigned
Coverage: Selected register-only 128/256-bit legacy and VEX forms. Memory, MMX, EVEX/AVX-512 and scalar floating-point forms are outside this selection.

Exception information & execution requirements

#NM
#UD

Feature availability, operating-system vector-state enablement and applicable floating-point exception controls still apply.

Feature availability alone does not guarantee execution: OS state and execution-level controls also apply. Use the linked architecture documentation for the full exception conditions.

Performance measurements are not included in this preview. Latency and throughput depend on the exact form and microarchitecture. Measured data on uops.info ↗

Sources & provenance#

Technical fields are imported from pinned upstream files. Explanations and explorer behavior are maintained separately.

Intel · PCMPEQB-PCMPEQW-PCMPEQD-Compare-Packed-Data-for-Equal.xml

Revision: 4ebe7f0ac1bd00f46244c49bb72c503ce368def7
SHA-256: 59d53ee27d2e755500261f64d760c8b748299d2e55b0298e78e1777197f83b64
Terms: Intel SDM terms; see License.md

View pinned upstream file ↗

Intel · intrinsics.xml

Revision: 4ebe7f0ac1bd00f46244c49bb72c503ce368def7
SHA-256: 6762a50652a35ef663fd532ed83b789d19bbc2ac7e94b1771f19d666d96c2c30
Terms: Intel SDM terms; see License.md