[llvm-bugs] [Bug 49611] New: Need multiple errata workaround options for loongson

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49611

            Bug ID: 49611
           Summary: Need multiple errata workaround options for loongson
           Product: libraries
           Version: trunk
          Hardware: Other
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: MIPS
          Assignee: unassignedbugs at nondot.org
          Reporter: arthur200126 at gmail.com
                CC: llvm-bugs at lists.llvm.org

Our distro at aosc.io builds packages for the MIPS64 loongson devices some of
our users (and devs) have, but we cannot use Clang because many of the loongson
errata are only fixed in GCC. We request LLVM to implement options to fix the
following issues:

## Loongson 2F

Loongson 2F has issues with its NOP and jump instructions. The hanging NOP one
can affect userspace, while the deadlocking jump one can only affect kernel
code. A description is found in [1].

  [1]: https://sourceware.org/legacy-ml/binutils/2009-11/msg00387.html

Loongson 2F is an older model, but we do wish that our netbooks can use some
proper Rust code.

## Loongson 3 (LLSC)

Loongson 3 is the current generation of Loongson CPUs. It can run into a
deadlock with ll/sc. The workaround involves putting a sync before ll and some
other stuff with sc.[2]

  [2]:
https://binutils.sourceware.narkive.com/dP1eQBrO/patch-mips-add-fix-for-loongson3-llsc-errata

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