[lldb][AArch64] Add Scalable Matrix Extension option to QEMU launch script

[DavidSpickett]

Summary

The Scalable Matrix Extension (SME) does not require extra options
beyond setting the cpu to "max".

https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html#sme-cpu-property-examples

SME depends on SVE, so that will be enabled too even if you don't ask
for it by name.

--sve --sme -> SVE and SME
--sme -> SVE and SME
--sve -> Only SVE

[DavidSpickett]

Strictly you could just use --sve, but it's nice to have an explicit option.

[omjavaid]

This looks good.

lldb/docs/use/qemu-testing.rst

 * Linux kernel image must be built from source using setup.sh or provided via
   --kernel commandline argument.
 
 * linux.build and qemu.git folder must be present in current directory if
   setup.sh was used to build Linux kernel and QEMU binaries.
 
 * --sve option will enable AArch64 SVE mode.
 
-* --mte option will enable AArch64 MTE (memory tagging) mode.
-  (can be used on its own or in addition to --sve)
+* --sme option will enable AArch64 SME mode (SME requires SVE, so this will also
+  be enabled).
+
+* --mte option will enable AArch64 MTE (memory tagging) mode
+  (can be used on its own or in addition to --sve).
 
 
 **Example:** Run QEMU Arm or AArch64 system emulation using run-qemu.sh
 ::
 
   $ sudo bash run-qemu.sh --arch arm --rootfs <path of rootfs image>
   $ sudo bash run-qemu.sh --arch arm64 --rootfs <path of rootfs image>
 

lldb/scripts/lldb-test-qemu/run-qemu.sh

 #!/bin/bash
 
 print_usage() {
   echo "Usage: $(basename $0) --arch [arm|arm64] [options]"
   echo -e "Starts QEMU system mode emulation for the architecture.\n"
   echo -e "  --help\t\t\tDisplay this information."
   echo -e "  --arch {arm|arm64}\t\tSelects architecture QEMU system emulation."
   echo -e "  --sve\t\t\t\tEnables AArch64 SVE mode."
-  echo -e "  --mte\t\t\t\tEnables AArch64 MTE mode.\n"
+  echo -e "  --mte\t\t\t\tEnables AArch64 MTE mode."
+  echo -e "  --sme\t\t\t\tEnables AArch64 SME mode."
   echo -e "  --rootfs {path}\t\tPath of root file system image."
   echo -e "  --qemu {path}\t\t\tPath of pre-installed qemu-system-* executable."
   echo -e "  --kernel {path}\t\tPath of Linux kernel prebuilt image.\n"
   echo -e "By default this utility will use:"
   echo -e "  QEMU image built from source in qemu.git directory"
   echo -e "  Linux kernel image from linux.build/(arm or arm64) directory."
   echo -e "Custom Linux kernel image or QEMU binary can be provided using commandline."
   exit "$1"

 while [[ $# -gt 0 ]]; do
   case "${END_OF_OPT}${1}" in
     --arch)     ARCH=$2; shift;;
     --rootfs)   ROOTFS_IMG=$2; shift;;
     --kernel)   KERNEL_IMG=$2; shift;;
     --qemu)     QEMU_BIN=$2; shift;;
     --sve)      SVE=1;;
     --mte)      MTE=1;;
+    --sme)      SME=1;;
     --help)     print_usage 0 ;;
     *)          invalid_arg "$1" ;;
   esac
   shift
 done
 
 if [ "$ARCH" == "arm64" ] && [ "$ARCH" == "arm" ]; then
   echo "Invalid architecture: $ARCH"
if [[ "$ARCH" == "arm" ]]; then
   QEMU_CPU="cortex-a15"
 
   if [[ $SVE ]]; then
     echo "warning: --sve is supported by AArch64 targets only"
   fi
   if [[ $MTE ]]; then
     echo "warning: --mte is supported by AArch64 targets only"
   fi
+  if [[ $SME ]]; then
+    echo "warning: --sme is supported by AArch64 targets only"
+  fi
 elif [[ "$ARCH" == "arm64" ]]; then
   QEMU_MACHINE=virt
   QEMU_SVE_MAX_VQ=4
   QEMU_CPU="cortex-a53"
 
-  if [[ $SVE ]] || [[ $MTE ]]; then
+  if [[ $SVE ]] || [[ $MTE ]] || [[ $SME ]]; then
     QEMU_CPU="max"
   fi
 
-  if [[ $SVE ]]; then
+  if [[ $SVE ]] || [[ $SME ]]; then
     QEMU_CPU="$QEMU_CPU,sve-max-vq=$QEMU_SVE_MAX_VQ"
   fi
   if [[ $MTE ]]; then
     QEMU_MACHINE="$QEMU_MACHINE,mte=on"
   fi
 fi
 
 run_qemu