ds_cmpstore_b32 GPU Native ISA AMD Vector

LDS / Data Share

ds_cmpstore_b32

Compare an unsigned 32-bit integer value in the data comparison register with a location in a data share, and modify the memory location with a value…

Also written as ds_cmpst_b32. AMD's machine-readable ISA specification lists this name for the same instruction.

Encoding

Binary Layout (AMD CDNA 5)
VDST
63:56
DATA1
55:48
DATA0
47:40
ADDR
39:32
110110
31:26
00010000
25:18
unassigned
17:16
OFFSET1
15:8
OFFSET0
7:0
 

The ENC_VDS layout from AMD's machine-readable ISA specification (AMD CDNA 5). Opcode 16 in OP rebuilds 0x00000000D8400000, an identifier AMD lists for this encoding. Bits marked unassigned have no field in the specification. Not the same in every generation: AMD RDNA 3.5 (encoding ENC_DS, field layout), AMD RDNA 3 (encoding ENC_DS, field layout). The same in AMD RDNA 4.

Format DS
Width 64 bits
Opcode 16
Identifier 0x00000000D8400000

Operands

  • ADDR
    Read. Operand must be a vector GPR. Uses an 8-bit operand field. Data format: 32 bits of arbitrary data. (OPR_VGPR, FMT_NUM_B32)
  • DATA0
    Read. Operand must be a vector GPR. Uses an 8-bit operand field. Data format: 32 bits of arbitrary data. (OPR_VGPR, FMT_NUM_B32)
  • DATA1
    Read. Operand must be a vector GPR. Uses an 8-bit operand field. Data format: 32 bits of arbitrary data. (OPR_VGPR, FMT_NUM_B32)

In AMD's order, as its machine-readable ISA specification lists them for the ENC_VDS encoding (AMD CDNA 5).

GFX Target Compatibility

TargetSupport
gfx1100✅ Supported

Related PTX Concepts

Atomic Compare-and-Swap ↗
equivalent with restrictions
atom (PTX)

Related

More in LDS / Data Share

Reference

AMDGPU / GFX ISA

Description

Compare an unsigned 32-bit integer value in the data comparison register with a location in a data share, and modify the memory location with a value in the data source register if the comparison is equal.

Example

ds_cmpstore_b32 v1, v2, v3

A real instruction accepted by the LLVM assembler, taken verbatim from LLVM's own AMDGPU MC test suite. Not from an AMD document, and not authored here.

Sources