add configuration option for reserved behavior vsew >= 100. - #1573
Jiacheng Tong (challenger1024) wants to merge 1 commit into
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| Vsew_Fatal => reserved_behavior("vsew contains reserved value: " ^ bits_str(v) ^ "."), | ||
| // The caller will detect the return value and invoke handle_illegal_vtype(). | ||
| Vsew_Illegal => true, | ||
| } else false |
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I'm not sure about this, it seems weird that this function would have side effects.
Can we do the check when you actually write vsew instead?
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In model/extensions/V/vext_vset_insts.sail, the execute_vsetvl_type function calls is_invalid_sew_pow, and the subsequent write only occurs when the check passes. Given this control flow, I was wondering whether my modification could still introduce any unintended side effects.
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Hmm, I think I would just have one config option base.reserved_behavior.vtype, and put the code in handle_illegal_vtype. Although this technically isn't "reserved behaviour" in the sense that implementations are allowed to do anything, so I'm starting to thing we just shouldn't do this at all.
See https://riscv-isa-manual.timhutt.co.uk/riscv-unprivileged.html#_unsupported_vtype_values
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So should I close this PR?
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Yeah I think so. Sorry about that!
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