ds_dec_rtn_u32 GPU Native ISA AMD Vector
DS DEC RTN U32 LDS / Data Share
ds_dec_rtn_u32
Decrement an unsigned 32-bit integer value from a location in a data share with wraparound to a value in the data register if the decrement yields a…
Encoding
Verified bit-level encoding data is not yet available for this instruction.
The instruction-format classification below (DS)
is well-documented and stable; exact per-target opcode/field bit positions have not
yet been imported from a verified source.
Operands
Operand details have not yet been curated for this instruction.
GFX Target Compatibility
| Target | Support |
|---|---|
| gfx1100 | ✅ Supported |
Related
More in LDS / Data Share
Reference
AMDGPU / GFX ISA
Description
Decrement an unsigned 32-bit integer value from a location in a data share with wraparound to a value in the data register if the decrement yields a negative value. Store the original value from data share into a vector register.
Semantics
addr = CalcDsAddr(ADDR.b32, OFFSET0.b32, OFFSET1.b32);
tmp = MEM[addr].u32;
src = DATA.u32;
MEM[addr].u32 = ((tmp == 0U) || (tmp > src)) ? src : tmp - 1U;
RETURN_DATA.u32 = tmp
Example
ds_dec_rtn_u32 v5, v1, v2A real instruction accepted by the LLVM assembler, taken verbatim from LLVM's own AMDGPU MC test suite (gfx11). Not from an AMD document, and not authored here.
Sources
- User Guide for AMDGPU Backend ↗ - LLVM Project
-
"AMD Instinct MI300" Instruction Set Architecture: Reference Guide ↗
- Advanced Micro Devices, Inc.
Reference Guide, page 426. - LLVM MC assembler tests for AMDGPU (gfx11) ↗ - LLVM Project