SETGP, SETGM, SETGE

Memory set with tag setting

These instructions set a requested number of bytes in memory to the value in the least significant byte of the source data register and store an Allocation Tag to memory for each Tag Granule written. The Allocation Tag is calculated from the Logical Address Tag in the register that holds the first address to be set. The prologue, main, and epilogue instructions are expected to be run in succession and to appear consecutively in memory: SETGP, then SETGM, and then SETGE.

SETGP performs some preconditioning of the arguments suitable for using the SETGM instruction, and sets an IMPLEMENTATION DEFINED portion of the requested number of bytes. SETGM sets a further IMPLEMENTATION DEFINED portion of the remaining bytes. SETGE sets any final remaining bytes.

For more information on exceptions specific to memory set instructions, see Memory Copy and Memory Set exceptions.

The architecture supports two algorithms for the memory set: option A and option B. Which algorithm is used is IMPLEMENTATION DEFINED.

For SETGP:

• If Xn<63> == 1, the set size is saturated to 0x7FFFFFFFFFFFFFF0.

On completion of SETGP, option A:

• Xn holds -1 times the number of bytes in the saturated set size remaining to be set.
• Xd holds the original Xd + saturated set size.
• PSTATE.{N,Z,C,V} are set to {0,0,0,0}.

On completion of SETGP, option B:

• Xn holds the number of bytes in the saturated set size remaining to be set.
• Xd holds the lowest address that has not been set.
• PSTATE.{N,Z,C,V} are set to {0,0,1,0}.

For SETGM, option A, when PSTATE.C = 0:

• Xn holds a signed 64-bit integer.
• Xn holds -1 times the number of bytes remaining to be set.
• Xd holds the lowest address to be set - Xn.
• On completion of the instruction, Xn holds -1 times the number of bytes remaining to be set.

For SETGM, option B, when PSTATE.C = 1:

• Xn holds the number of bytes remaining to be set.
• Xd holds the lowest address to be set.
• On completion of the instruction:
  • Xn holds the number of bytes remaining to be set.
  • Xd holds the lowest address that has not been set.

For SETGE, option A, when PSTATE.C = 0:

• Xn holds a signed 64-bit integer.
• Xn holds -1 times the number of bytes remaining to be set.
• Xd holds the lowest address to be set - Xn.
• On completion of the instruction, Xn holds 0.

For SETGE, option B, when PSTATE.C = 1:

• Xn holds the number of bytes remaining to be set.
• Xd holds the lowest address to be set.
• On completion of the instruction:
  • Xn holds 0.
  • Xd holds the lowest address that has not been set.

Integer
(FEAT_MOPS)

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_MOPS) || !IsFeatureImplemented(FEAT_MTE) || sz != '00' then EndOfDecode(Decode_UNDEF); SETParams memset; memset.d = UInt(Rd); memset.s = UInt(Rs); memset.n = UInt(Rn); constant bits(2) options = op2<1:0>; constant boolean nontemporal = options<1> == '1'; case op2<3:2> of when '00' memset.stage = MOPSStage_Prologue; when '01' memset.stage = MOPSStage_Main; when '10' memset.stage = MOPSStage_Epilogue; otherwise EndOfDecode(Decode_UNDEF);

Assembler Symbols