STZ2G Store Allocation Tags, zeroing This instruction stores an Allocation Tag to two Tag Granules of memory, zeroing the associated data locations. The address used for the store is calculated from the base register and an immediate signed offset scaled by the Tag Granule. The Allocation Tag is calculated from the Logical Address Tag in the source register. This instruction generates an Unchecked access. It has encodings from 3 classes: Post-index , Pre-index and Signed offset 1 1 0 1 1 0 0 1 1 1 1 0 1 STZ2G <Xt|SP>, [<Xn|SP>], #<simm> if !IsFeatureImplemented(FEAT_MTE) then UNDEFINED; constant integer t = UInt(Xt); constant integer n = UInt(Xn); constant bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); constant boolean writeback = TRUE; constant boolean postindex = TRUE; 1 1 0 1 1 0 0 1 1 1 1 1 1 STZ2G <Xt|SP>, [<Xn|SP>, #<simm>]! if !IsFeatureImplemented(FEAT_MTE) then UNDEFINED; constant integer t = UInt(Xt); constant integer n = UInt(Xn); constant bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); constant boolean writeback = TRUE; constant boolean postindex = FALSE; 1 1 0 1 1 0 0 1 1 1 1 1 0 STZ2G <Xt|SP>, [<Xn|SP>{, #<simm>}] if !IsFeatureImplemented(FEAT_MTE) then UNDEFINED; constant integer t = UInt(Xt); constant integer n = UInt(Xn); constant bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); constant boolean writeback = FALSE; constant boolean postindex = FALSE; <Xt|SP> Is the 64-bit name of the general-purpose source register or stack pointer, encoded in the "Xt" field. <Xn|SP> Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Xn" field. <simm> Is the optional signed immediate offset, a multiple of 16 in the range -4096 to 4080, defaulting to 0 and encoded in the "imm9" field. bits(64) address; bits(64) address2; constant bits(64) data = if t == 31 then SP[] else X[t, 64]; constant bits(4) tag = AArch64.AllocationTagFromAddress(data); if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n, 64]; constant boolean devstoreunpred = FALSE; constant AccessDescriptor accdesc = CreateAccDescLDGSTG(MemOp_STORE, devstoreunpred); if !postindex then address = AddressAdd(address, offset, accdesc); address2 = AddressIncrement(address, TAG_GRANULE, accdesc); if !IsAligned(address, TAG_GRANULE) then AArch64.Abort(address, AlignmentFault(accdesc)); Mem[address , TAG_GRANULE, accdesc] = Zeros(TAG_GRANULE * 8); Mem[address2, TAG_GRANULE, accdesc] = Zeros(TAG_GRANULE * 8); AArch64.MemTag[address , accdesc] = tag; AArch64.MemTag[address2, accdesc] = tag; if writeback then if postindex then address = AddressAdd(address, offset, accdesc); if n == 31 then SP[] = address; else X[n, 64] = address;