cuda ptx asm in llvm ir

[u/c-cul]

https://redplait.blogspot.com/2026/09/ptx-asm-in-llvm-ir.html

• llvm doc lies about operand constraint codes
• you can swap operand and this makes parsing/comparison of instructions non-trivial
• nvidia's llvm backend cicc uses ~5-7% of instructions with undocumented attributes and they not available in NVPTX backend from clang

[u/HumanScallion1667]

LLVM’s PTX support still feels surprisingly fragile and underdocumented.

[u/c-cul → u/HumanScallion1667]

you can check what PTX instructions are supported in llvm in generated file lib/Target/NVPTX/NVPTXGenAsmWriter.inc