s_bitset1_b32 GPU Native ISA AMD Scalar

Scalar Arithmetic

s_bitset1_b32

Given a bit offset in a scalar input, set the indicated bit in the destination scalar register to 1.

Encoding

Binary Layout (AMD CDNA 5)
101111101
31:23
SDST
22:16
00010010
15:8
SSRC0
7:0
 

The ENC_SOP1 layout from AMD's machine-readable ISA specification (AMD CDNA 5). Opcode 18 in OP rebuilds 0xBE801200, an identifier AMD lists for this encoding. Not the same in every generation: AMD CDNA 4 (opcode 26), AMD CDNA 3 (opcode 26), AMD CDNA 2 (opcode 26), AMD CDNA 1 (opcode 26), AMD RDNA 2 (opcode 29), AMD RDNA 1 (opcode 29). The same in AMD RDNA 4, AMD RDNA 3.5, AMD RDNA 3.

Format SOP1
Width 32 bits
Opcode 18
Identifier 0xBE801200

Operands

  • SDST
    Written. All scalar destination operands. Data format: 32 bits of arbitrary data. (OPR_SDST, FMT_NUM_B32)
  • SSRC0
    Read. All scalar operands. Covers all operands that are allowed as scalar sources. Data format: Unsigned 32-bit integral data. (OPR_SSRC, FMT_NUM_U32)

In AMD's order, as its machine-readable ISA specification lists them for the ENC_SOP1 encoding (AMD CDNA 5).

GFX Target Compatibility

TargetSupport
gfx1100✅ Supported

Related

More in Scalar Arithmetic

Reference

AMDGPU / GFX ISA

Semantics

D0.u32[S0.u32[4 : 0]] = 1'1U

Example

s_bitset1_b32 s0, 0

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