If vtype.vill=1, is VLMAX equal to 0? If vlamx=0, then any value configured for vstart is treated as an illegal instruction, because in this case, any vstart value is greater than the element index.

riscvarchive / riscv-v-spec

Working draft of the proposed RISC-V V vector extension

https://jira.riscv.org/browse/RVG-122

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If vtype.vill=1, is VLMAX equal to 0? If vlamx=0, then any value configured for vstart is treated as an illegal instruction, because in this case, any vstart value is greater than the element index. #907

Open Wei-VV1995 opened 1 year ago

Wei-VV1995 commented 1 year ago

“The use of vstart values greater than the largest element index for the current SEW setting is reserved” If vtype.vill=1, is VLMAX equal to 0? If vlamx=0, then any value configured for vstart is treated as an illegal instruction, because in this case, any vstart value is greater than the element index. Is my understanding correct?

aswaterman commented 1 year ago

Yes. (More accurately, vstart >= vl is reserved, not necessarily illegal, but in practice you have the right idea.)