VZEROALL — Zero XMM, YMM, and ZMM Registers

Opcode/Instruction Op /En 64/32 bit Mode Support CPUID Feature Flag Description
VEX.256.0F.WIG 77 VZEROALL ZO V/V AVX Zero some of the XMM, YMM, and ZMM registers.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4


In 64-bit mode, the instruction zeroes XMM0-XMM15, YMM0-YMM15, and ZMM0-ZMM15. Outside 64-bit mode, it zeroes only XMM0-XMM7, YMM0-YMM7, and ZMM0-ZMM7. VZEROALL does not modify ZMM16-ZMM31.

Note: VEX.vvvv is reserved and must be 1111b, otherwise instructions will #UD. In Compatibility and legacy 32-bit mode only the lower 8 registers are modified.


simd_reg_file[][] is a two dimensional array representing the SIMD register file containing all the overlapping xmm, ymm, and zmm
registers present in that implementation. The major dimension is the register number: 0 for xmm0, ymm0, and zmm0; 1 for xmm1,
ymm1, and zmm1; etc. The minor dimension size is the width of the implemented SIMD state measured in bits. On a machine
supporting Intel AVX-512, the width is 512.

VZEROALL (VEX.256 encoded version)

IF (64-bit mode)
    limit :=15
    limit := 7
FOR i in 0 .. limit:
    simd_reg_file[i][MAXVL-1:0] := 0

Intel C/C++ Compiler Intrinsic Equivalent

VZEROALL: _mm256_zeroall()

SIMD Floating-Point Exceptions


Other Exceptions

See Table 2-25, “Type 8 Class Exception Conditions.”