lowRISC / lowRISC/lowrisc-toolchains

LLVM Toolchain does not recognise `slo`,`sro` family of instructions

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Description

`slo`, `slow`, `sloi`, `sloiw`, `sro`, `srow`, `sroi`, `sroiw` are erroneously missing from the table of instructions in the extensions defined in the Bitmanip 0.93 spec, though they are present in the document and the Change History at the end shows they were moved to Zbp.

These are implemented by Ibex, and we currently use `.insn` instead of mnemonics to write the instructions in assembly: [Ibex ISA Test](https://github.com/lowRISC/opentitan/blob/2c2012c564c259cde4c8bd58e85d7a724288528b/sw/device/tests/rv_core_ibex_isa_test.S#L377-L380)

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  1. Read the whole issue, then the project's contributing guide.
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  3. Fork the repository and make your change on a branch.
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Research direction

Locate the LLVM instruction tables for the Bitmanip 0.93 extensions and compare them with the listed `slo`, `slow`, `sloi`, `sloiw`, `sro`, `srow`, `sroi`, and `sroiw` mnemonics. Review the referenced Ibex ISA test at `sw/device/tests/rv_core_ibex_isa_test.S` around lines 377-380, then verify that assembly can use the mnemonics instead of `.insn`.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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