stable-rc: 5.10: riscv: defconfig: clang-nightly: build failed - Invalid or unknown z ISA extension: 'zifencei'

[Naresh Kamboju]

The riscv defconfig and tinyconfig builds failed with clang-nightly
due to below build warnings / errors on latest stable-rc 5.10.

Regression on riscv:
  - build/clang-nightly-tinyconfig - FAILED
  - build/clang-nightly-defconfig - FAILED

Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>

metadata:
-----
  git_repo: https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc
  git_sha: 7d11e4c4fc56eb25c5b41da93748dbcf21956316
  git_short_log: 7d11e4c4fc56 ("Linux 5.10.169-rc1")
  git_describe: v5.10.168-58-g7d11e4c4fc56

Build log:
----
make --silent --keep-going --jobs=8
O=/home/tuxbuild/.cache/tuxmake/builds/1/build ARCH=riscv
CROSS_COMPILE=riscv64-linux-gnu- HOSTCC=clang CC=clang LLVM=1
LLVM_IAS=1 LD=riscv64-linux-gnu-ld
riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_zicsr2p0_zifencei2p0:
Invalid or unknown z ISA extension: 'zifencei'
riscv64-linux-gnu-ld: failed to merge target specific data of file
init/version.o
riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_zicsr2p0_zifencei2p0:
Invalid or unknown z ISA extension: 'zifencei'
riscv64-linux-gnu-ld: failed to merge target specific data of file
init/do_mounts.o
riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_zicsr2p0_zifencei2p0:
Invalid or unknown z ISA extension: 'zifencei'
riscv64-linux-gnu-ld: failed to merge target specific data of file
init/noinitramfs.o
riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_zicsr2p0_zifencei2p0:
Invalid or unknown z ISA extension: 'zifencei'
riscv64-linux-gnu-ld: failed to merge target specific data of file
init/calibrate.o
riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_zicsr2p0_zifencei2p0:
Invalid or unknown z ISA extension: 'zifencei'

Build details,
https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-5.10.y/build/v5.10.168-58-g7d11e4c4fc56/testrun/14869376/suite/build/test/clang-nightly-tinyconfig/details/

Build history,
https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-5.10.y/build/v5.10.168-58-ga96fb51aec5a/testrun/14866489/suite/build/test/clang-nightly-defconfig/details/

https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-5.10.y/build/v5.10.168-58-g7d11e4c4fc56/testrun/14869376/suite/build/test/clang-nightly-tinyconfig/history/

steps to reproduce:
-----------
# To install tuxmake on your system globally:
# sudo pip3 install -U tuxmake
#
# See https://docs.tuxmake.org/ for complete documentation.
# Original tuxmake command with fragments listed below.
# tuxmake --runtime podman --target-arch riscv --toolchain
clang-nightly --kconfig tinyconfig LLVM=1 LLVM_IAS=1
LD=riscv64-linux-gnu-ld

--
Linaro LKFT
https://lkft.linaro.org