RVOPcode
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Register Guide

RISC-V v21 / v21 Register: Vector data register

v21 is an RVV vector register; element count and layout are controlled by vl, vtype, VLEN, and LMUL.

ABI name: v21; physical register: v21.
Save rule: Caller.
Read it through its psABI role first, then inspect how each instruction reads or writes it.
Physical Name v21ABI Name v21Save Rule Caller
Role
Vector data register
Convention
Caller-saved
Remember This First
The calling convention listed for this entry is: Caller-saved.
psABI Vector Register Reference

ABI register

v21 is an RVV vector register; element count and layout are controlled by vl, vtype, VLEN, and LMUL.

Preserved across calls: Caller
RISC-V psABI vector register convention

When It Fits Best

  • - Use it according to the documented role: Vector data register.
  • - Consult the applicable ISA or ABI specification for concrete read, write, or execution semantics.

When Not To Use It This Way

  • - Do not apply the integer temporary-register t* rules to this entry.
  • - Do not infer behavior not defined by this page or the applicable specification from the ABI name.

What Happens Around A Call

1

The calling convention listed for this entry is: Caller-saved.

2

The save rule listed for this entry is: Caller.

Read The Documented Role

Examples explain the rule, not a complete program
# v21 / v21
# Vector data register
# Caller-saved