VPGATHERDD/VPGATHERQD — Gather Packed Dword Values Using Signed Dword/Qword Indices Instruction Operand EncodingDescriptionThe instruction conditionally loads up to 4 or 8 dword values from memory addresses specified by the memory operand (the second operand) and using dword indices. The memory operand uses the VSIB form of the SIB byte to specify a general purpose register operand as the common base, a vector register for an array of indices relative to the base and a constant scale factor.The mask operand (the third operand) specifies the conditional load operation from each memory address and the corresponding update of each data element of the destination operand (the first operand). Conditionality is speci-fied by the most significant bit of each data element of the mask register. If an element’s mask bit is not set, the corresponding element of the destination register is left unchanged. The width of data element in the destination register and mask register are identical. The entire mask register will be set to zero by this instruction unless the instruction causes an exception. Using qword indices, the instruction conditionally loads up to 2 or 4 qword values from the VSIB addressing memory operand, and updates the lower half of the destination register. The upper 128 or 256 bits of the destina-tion register are zero’ed with qword indices.This instruction can be suspended by an exception if at least one element is already gathered (i.e., if the exception is triggered by an element other than the rightmost one with its mask bit set). When this happens, the destination register and the mask operand are partially updated; those elements that have been gathered are placed into the destination register and have their mask bits set to zero. If any traps or interrupts are pending from already gath-ered elements, they will be delivered in lieu of the exception; in this case, EFLAG.RF is set to one so an instruction breakpoint is not re-triggered when the instruction is continued.If the data size and index size are different, part of the destination register and part of the mask register do not correspond to any elements being gathered. This instruction sets those parts to zero. It may do this to one or both of those registers even if the instruction triggers an exception, and even if the instruction triggers the exception before gathering any elements.VEX.128 version: For dword indices, the instruction will gather four dword values. For qword indices, the instruction will gather two values and zero the upper 64 bits of the destination.Opcode/InstructionOp/ En64/32-bit ModeCPUID Feature FlagDescriptionVEX.128.66.0F38.W0 90 /rVPGATHERDD xmm1, vm32x, xmm2RMVV/VAVX2Using dword indices specified in vm32x, gather dword val-ues from memory conditioned on mask specified by xmm2. Conditionally gathered elements are merged into xmm1.VEX.128.66.0F38.W0 91 /rVPGATHERQD xmm1, vm64x, xmm2RMVV/VAVX2Using qword indices specified in vm64x, gather dword val-ues from memory conditioned on mask specified by xmm2. Conditionally gathered elements are merged into xmm1.VEX.256.66.0F38.W0 90 /rVPGATHERDD ymm1, vm32y, ymm2RMVV/VAVX2Using dword indices specified in vm32y, gather dword from memory conditioned on mask specified by ymm2. Conditionally gathered elements are merged into ymm1.VEX.256.66.0F38.W0 91 /rVPGATHERQD xmm1, vm64y, xmm2RMVV/VAVX2Using qword indices specified in vm64y, gather dword val-ues from memory conditioned on mask specified by xmm2. Conditionally gathered elements are merged into xmm1.Op/EnOperand 1Operand 2Operand 3Operand 4RMVModRM:reg (r,w)BaseReg (R): VSIB:base,VectorReg(R): VSIB:indexVEX.vvvv (r, w)NA
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