On 28/04/2022 10:40, Andrea Corallo via Gcc-patches wrote:
Add targeting-checking entities for PACBTI in testsuite
framework.
Pre-approved with the requested changes here
<https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586331.html>.
gcc/testsuite/ChangeLog:
* testsuite/lib/target-supports.exp:
(check_effective_target_arm_pacbti_hw): New.
* doc/sourcebuild.texi: Document arm_pacbti_hw.
Co-Authored-By: Tejas Belagod <tbela...@arm.com>
+proc check_effective_target_arm_pacbti_hw {} {
+ return [check_runtime arm_pacbti_hw_available {
+ __attribute__ ((naked)) int
+ main (void)
+ {
+ asm ("pac r12, lr, sp");
So the armv8-m Arm ARM says that this instruction is in the NOP space
and that it is undefined if we aren't armv8-m.main or higher.
+ asm ("mov r0, #0");
+ asm ("autg r12, lr, sp");
This isn't in the nop space, but the Arm ARM says it is unpredictable if
the extension isn't present. Unfortunately, that means this isn't a
particularly reliable way of detecting that the PACBTI feature is present.
However, I can't think off hand of more reliable way of testing this
since reading the feature register ID_ISAR5 is not possible when in
unprivileged mode.
So I think we'll have to live with this.
+ asm ("bx lr");
+ }
+ } ""]
OK.
R.
