CHERI encodings and CSRs #214
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tariqkurd-repo
commented
Dec 19, 2023
tariqkurd-repo
commented
- first attempt at CSRs and encodings for CHERI
- note that lr/b etc will be a separate extension eventually
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This is my first attempt at reserving some encoding and CSR space for CHERI. LR.B, LR.H, SC.B, SC.H need to be in a separate extension, but for use by CHERI software |
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Using this repo to reserve opcode space far in advance of an extension's proposal isn't standard practice, and this is an even more unusual corner case since it's really a new base ISA. Still, I think it's helpful to leave this PR open so people can look at the concrete proposal.
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Our intention is to keep CHERI as compatible as possible with other extensions, and so tentatively reserving encoding space and CSR numbers help with that goal. When the TG gets going next year we'll make a more formal proposal. |
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@aswaterman this branch builds OK - but the |
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LLVM also includes a mechanism for detecting encoding conflicts, but it too failed to identify this. Perhaps for the same reason stated by above. |
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I've changed this to the intended encoding, which is already in riscv-opcodes (riscv/riscv-opcodes#214). The previous one was a typo and conflicted with c.subw.
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See: #237 |
