s_setprio GPU Native ISA AMD Scalar

Branch & Control

s_setprio

Change wave user priority.

Encoding

Binary Layout (AMD CDNA 5)
101111111
31:23
0110101
22:16
SIMM16
15:0
 

The ENC_SOPP layout from AMD's machine-readable ISA specification (AMD CDNA 5). Opcode 53 in OP rebuilds 0xBFB50000, an identifier AMD lists for this encoding. Not the same in every generation: AMD CDNA 4 (opcode 15), AMD CDNA 3 (opcode 15), AMD CDNA 2 (opcode 15), AMD CDNA 1 (opcode 15), AMD RDNA 2 (opcode 15), AMD RDNA 1 (opcode 15). The same in AMD RDNA 4, AMD RDNA 3.5, AMD RDNA 3.

Format SOPP
Width 32 bits
Opcode 53
Identifier 0xBFB50000

Operands

  • SIMM16
    Read. 16-bit integer constant. Data format: 16 bits of arbitrary data. (OPR_SIMM16, FMT_NUM_B16)

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

GFX Target Compatibility

TargetSupport
gfx1100✅ Supported

Related

More in Branch & Control

Reference

AMDGPU / GFX ISA

Semantics

User settable wave priority is set to SIMM16[1:0]. 0 = lowest, 3 = highest. The overall wave priority is {SPIPrio[1:0], UserPrio[1:0], WaveAge[3:0]}.

Example

s_setprio 0x0

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