[PATCH v1 1/4] aarch64: make explicit that CFI gnu_window_save is for Sparc, not AArch64

[Indu Bhagat]

On 11/25/24 8:28 AM, Matthieu Longo wrote:
> - add a detailed comment when parsing DW_CFA_GNU_window_save in SFrame to
>    explain why we are checking whether the targeted architecture is AArch64,
>    whereas this CFI is a Sparc extension.
> - replace .cfi_gnu_window_save by .cfi_negate_ra_state in existing AArch64
>    DWARF tests as this is the preferred directive since GCC 15.
> - add a new AARch64 test to check backward compatibility with old GCC
>    versions that emits .cfi_gnu_window_save.
> ---
>   gas/gen-sframe.c                              |  8 +++++-
>   gas/testsuite/gas/aarch64/pac_ab_key.s        |  4 +--
>   .../gas/aarch64/pac_compat_cfi_window_save.d  | 26 +++++++++++++++++++
>   .../gas/aarch64/pac_compat_cfi_window_save.s  | 20 ++++++++++++++
>   4 files changed, 55 insertions(+), 3 deletions(-)
>   create mode 100644 gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d
>   create mode 100644 gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s
> 
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index 626dc33b71d..be48b339609 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -1283,7 +1283,13 @@ sframe_xlate_do_aarch64_negate_ra_state (struct sframe_xlate_ctx *xlate_ctx,
>   }
>   
>   /* Translate DW_CFA_GNU_window_save into SFrame context.
> -   DW_CFA_AARCH64_negate_ra_state is multiplexed with DW_CFA_GNU_window_save.
> +   DW_CFA_GNU_window_save is a DWARF Sparc extension, but is multiplexed with a
> +   directive of DWARF AArch64 extension: DW_CFA_AARCH64_negate_ra_state.
> +   The AArch64 backend of GCC 14 and older versions was emitting mistakenly the
> +   Sparc CFI directive (.cfi_window_save). From GCC 15, the AArch64 backend only
> +   emits .cfi_negate_ra_state. For backward compatibility, the handler for
> +   .cfi_window_save needs to check whether the directive was used in a AArch ABI
> +   context or not.

Nit: There are a few "dot, space, space, new sentence" issues in the 
comment block above.

The patch looks OK to me otherwise,

Thanks
Indu

>      Return SFRAME_XLATE_OK if success.  */
>   
>   static int
> diff --git a/gas/testsuite/gas/aarch64/pac_ab_key.s b/gas/testsuite/gas/aarch64/pac_ab_key.s
> index 4b328e72ae4..3b81919409d 100644
> --- a/gas/testsuite/gas/aarch64/pac_ab_key.s
> +++ b/gas/testsuite/gas/aarch64/pac_ab_key.s
> @@ -7,7 +7,7 @@ _Z5foo_av:
>   .LFB0:
>   	.cfi_startproc
>   	hint	25 // paciasp
> -	.cfi_window_save
> +	.cfi_negate_ra_state
>   	stp	x29, x30, [sp, -16]!
>   	.cfi_def_cfa_offset 16
>   	.cfi_offset 29, -16
> @@ -23,7 +23,7 @@ _Z5foo_bv:
>   	.cfi_startproc
>   	.cfi_b_key_frame
>   	hint	27 // pacibsp
> -	.cfi_window_save
> +	.cfi_negate_ra_state
>   	stp	x29, x30, [sp, -16]!
>   	.cfi_def_cfa_offset 16
>   	.cfi_offset 29, -16
> diff --git a/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d
> new file mode 100644
> index 00000000000..f49cebcbfde
> --- /dev/null
> +++ b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d
> @@ -0,0 +1,26 @@
> +#objdump: --dwarf=frames
> +# This test is only valid on ELF based ports.
> +#notarget: *-*-*coff *-*-pe *-*-wince *-*-*aout* *-*-netbsd
> +
> +.+:     file .+
> +
> +Contents of the .eh_frame section:
> +
> +0+ 0+10 0+ CIE
> +  Version:               1
> +  Augmentation:          "zR"
> +  Code alignment factor: 4
> +  Data alignment factor: -8
> +  Return address column: 30
> +  Augmentation data:     1b
> +  DW_CFA_def_cfa: r31 \(sp\) ofs 0
> +
> +0+14 0+18 0+18 FDE cie=0+ pc=0+\.\.0+8
> +  DW_CFA_advance_loc: 4 to 0+4
> +  DW_CFA_AARCH64_negate_ra_state
> +  DW_CFA_advance_loc: 4 to 0+8
> +  DW_CFA_def_cfa_offset: 16
> +  DW_CFA_offset: r29 \(x29\) at cfa-16
> +  DW_CFA_offset: r30 \(x30\) at cfa-8
> +  DW_CFA_nop
> +  DW_CFA_nop
> diff --git a/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s
> new file mode 100644
> index 00000000000..1bfdef71f22
> --- /dev/null
> +++ b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s
> @@ -0,0 +1,20 @@
> +	.arch armv8-a
> +	.text
> +	.align	2
> +	.global	_Z5foo_av
> +	.type	_Z5foo_av, %function
> +_Z5foo_av:
> +.LFB0:
> +	.cfi_startproc
> +	hint	25 // paciasp
> +	.cfi_window_save
> +	stp	x29, x30, [sp, -16]!
> +	.cfi_def_cfa_offset 16
> +	.cfi_offset 29, -16
> +	.cfi_offset 30, -8
> +	.cfi_endproc
> +.LFE0:
> +	.size	_Z5foo_av, .-_Z5foo_av
> +	.align	2
> +	.global	_Z5foo_bv
> +	.type	_Z5foo_bv, %function