tree 8ebca6a3ff5a3b067ffd7a82736ae450542df266
parent 94600879ed7636dd5fc0e57c5835633f56de29ec
author Srinath Parvathaneni <srinath.parvathaneni@arm.com> 1660901649 +0200
committer Andrea Corallo <andrea.corallo@arm.com> 1660915378 +0200

[13/13] arm: Add support for dwarf debug directives and pseudo hard-register for PAC feature.

Hello,

This patch teaches the DWARF support in gcc about RA_AUTH_CODE pseudo hard-register and also
.save {ra_auth_code} and .cfi_offset ra_auth_code <offset> dwarf directives for the PAC feature
in Armv8.1-M architecture.

RA_AUTH_CODE register number is 107 and it's dwarf register number is 143.

When compiled with " -march=armv8.1-m.main -mbranch-protection=pac-ret+leaf+bti -mthumb
-mfloat-abi=soft -fasynchronous-unwind-tables -g -O2 -S" command line options, the assembly
output after this patch looks like below:

        ...
        .cfi_startproc
        pacbti  ip, lr, sp
        movs    r1, #40
        push    {ip, lr}
        .save {ra_auth_code, lr}
        .cfi_def_cfa_offset 8
        .cfi_offset 143, -8
        .cfi_offset 14, -4
        ...
        pop     {ip, lr}
        .cfi_restore 14
        .cfi_restore 143
        .cfi_def_cfa_offset 0
        movs    r0, #0
        aut     ip, lr, sp
        bx      lr
        .cfi_endproc
        ...

Regression tested on arm-none-eabi target and found no regressions.

Ok for master?

Regards,
Srinath.

gcc/ChangeLog:

2022-08-17  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

        * config/arm/aout.h (ra_auth_code): Add to enum.
        * config/arm/arm.cc (emit_multi_reg_push): Add RA_AUTH_CODE register to
        dwarf frame expression.
        (arm_emit_multi_reg_pop): Restore RA_AUTH_CODE register.
        (arm_expand_prologue): Mark as frame related insn.
        (arm_regno_class): Check for pac pseudo reigster.
        (arm_dbx_register_number): Assign ra_auth_code register number in dwarf.
        (arm_unwind_emit_sequence): Print .save directive with ra_auth_code
        register.
        (arm_conditional_register_usage): Mark ra_auth_code in fixed reigsters.
        * config/arm/arm.h (FIRST_PSEUDO_REGISTER): Modify.
        (IS_PAC_Pseudo_REGNUM): Define.
        (enum reg_class): Add PAC_REG entry.
        * config/arm/arm.md (RA_AUTH_CODE): Define.

gcc/testsuite/ChangeLog:

2022-08-17  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

        * g++.target/arm/pac-1.C: New test.
        * gcc.target/arm/pac-9.c: Likewise.

Testing Done:
@IP [Low Risk]: No to Q20 and no short-cut.

Arm specific changes.
==============
Rev 4:
@IP [Low Risk]: No to Q20 and no short-cut.

New testcase added.
===============
Rev 5.

@IP [Low Risk]: No to Q20 and no short-cut.

=======
Rev 6.

This is for internal discussion and testing.
=======
Rev 7.

Re-based the patch on internal branch origin/dsg/andcor03/pacbti-upstream-rebased.

This patch is under internal discussion and testing.
=====
Rev 8.

@IP: [Low Risk]: No to Q20 and no short-cut.
====
Rev 9.

@IP: [Low Risk]: No to Q20 and no short-cut.

Arm specific changes,
Re-based the patch on vendors/ARM/arm-12-m-pacbti branch and fixed build issue
related to stack offset in case of RA_AUTH_CODE register.

Bugs closed: GNUTOOLS-13069

Reviewed at http://pdtlreviewboard.cambridge.arm.com/r/14831/