Store Allocation Tag, Zeroing stores an Allocation Tag to memory, zeroing the associated data location. 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
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | imm9 | 0 | 1 | Xn | Xt | ||||||||||||||||
if !HaveMTEExt() then UNDEFINED; integer n = UInt(Xn); integer t = UInt(Xt); bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); boolean writeback = TRUE; boolean postindex = TRUE; boolean zero_data = TRUE;
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | imm9 | 1 | 1 | Xn | Xt | ||||||||||||||||
if !HaveMTEExt() then UNDEFINED; integer n = UInt(Xn); integer t = UInt(Xt); bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); boolean writeback = TRUE; boolean postindex = FALSE; boolean zero_data = TRUE;
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | imm9 | 1 | 0 | Xn | Xt | ||||||||||||||||
if !HaveMTEExt() then UNDEFINED; integer n = UInt(Xn); integer t = UInt(Xt); bits(64) offset = LSL(SignExtend(imm9, 64), LOG2_TAG_GRANULE); boolean writeback = FALSE; boolean postindex = FALSE; boolean zero_data = TRUE;
| <Xt|SP> |
Is the 64-bit name of the general-purpose register to be transferred, 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; SetTagCheckedInstruction(FALSE); if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n]; if !postindex then address = address + offset; if zero_data then if address != Align(address, TAG_GRANULE) then AArch64.Abort(address, AlignmentFault(AccType_NORMAL, TRUE, FALSE)); Mem[address, TAG_GRANULE, AccType_NORMAL] = Zeros(TAG_GRANULE * 8); bits(64) data = if t == 31 then SP[] else X[t]; bits(4) tag = AArch64.AllocationTagFromAddress(data); AArch64.MemTag[address, AccType_NORMAL] = tag; if writeback then if postindex then address = address + offset; if n == 31 then SP[] = address; else X[n] = address;
Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41
Copyright © 2010-2021 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.