Three-Input Bitwise Logic Bit Manipulation
Compute an arbitrary bitwise boolean function of three operands, selected by a truth-table constant.
Vendor-Neutral Definition
d = LUT[a, b, c], where LUT is an 8-bit truth table constant selecting the boolean function of the three 1-bit inputs at each bit position.
⚠️ Cross-vendor mappings describe semantic relationships and are not guaranteed one-to-one compiler
translations.
equivalent with restrictions
Both compute an arbitrary 3-input bitwise boolean function selected by an 8-bit truth-table immediate.
| Property | NVIDIA PTX | AMDGPU |
|---|---|---|
| Instruction | lop3 | v_bitop3_b32 |
| ISA Layer | Virtual | Native |
| Data Types | - | b32 |
| Version / Target Introduced | PTX ISA 4.3 | - |
Important Differences
- The truth-table encoding convention (which bit of the 8-bit immediate corresponds to which a/b/c input combination) is not guaranteed to be identical between PTX's lut and AMDGPU's bitop3 immediate - verify against both sources before porting a lut constant directly.
Source Evidence
- Parallel Thread Execution ISA ↗ - NVIDIA Corporation
- User Guide for AMDGPU Backend ↗ - LLVM Project
Verification method: documentation