[Bug target/124021] New: Interrupt function may clobber vstart on riscv

[law at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124021

            Bug ID: 124021
           Summary: Interrupt function may clobber vstart on riscv
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: law at gcc dot gnu.org
  Target Milestone: ---

I don't have a testcase handy as this was reported verbally to me.

Vector loads/stores implicitly set vstart on risc-v.  Therefore if we have an
interrupt routine that uses any vector code, we need to save/restore vstart in
the prologue/epilogue.