Re: [PATCH v3 11/15] gas: Skip SFrame FDE if .cfi_window_save

[Indu Bhagat <indu.bhagat@oracle.com>]

On 4/12/24 07:47, Jens Remus wrote:
> CFI opcode DW_CFA_AARCH64_negate_ra_state is multiplexed with
> DW_CFA_GNU_window_save. Process DW_CFA_AARCH64_negate_ra_state on
> AArch64. Skip generation of SFrame FDE otherwise.
> 
> gas/
> 	* gen-sframe.c: Skip SFrame FDE if .cfi_window_save.
> 

LGTM.

Thanks

> Signed-off-by: Jens Remus <jremus@linux.ibm.com>
> ---
> 
> Notes (jremus):
>      Changes v2 -> v3:
>      - New patch. The intention is to skip all "unknown" CFI opcodes,
>        which SFrame does not explicitly handle. DW_CFA_GNU_window_save
>        seems to be handled only for the AArch64-specific multiplexed
>        DW_CFA_AARCH64_negate_ra_state. The logic could be changed to be
>        dependent on TC_AARCH64 at build-time instead of
>        sframe_get_abi_arch() at run-time.
> 
>   gas/gen-sframe.c | 25 ++++++++++++++++++++++---
>   1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index 87be3eb05ad2..98166de8cc01 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -1257,12 +1257,12 @@ sframe_xlate_do_restore (struct sframe_xlate_ctx *xlate_ctx,
>     return SFRAME_XLATE_OK;
>   }
>   
> -/* Translate DW_CFA_GNU_window_save into SFrame context.
> +/* Translate DW_CFA_AARCH64_negate_ra_state into SFrame context.
>      Return SFRAME_XLATE_OK if success.  */
>   
>   static int
> -sframe_xlate_do_gnu_window_save (struct sframe_xlate_ctx *xlate_ctx,
> -				 struct cfi_insn_data *cfi_insn ATTRIBUTE_UNUSED)
> +sframe_xlate_do_aarch64_negate_ra_state (struct sframe_xlate_ctx *xlate_ctx,
> +					 struct cfi_insn_data *cfi_insn ATTRIBUTE_UNUSED)
>   {
>     struct sframe_row_entry *cur_fre = xlate_ctx->cur_fre;
>   
> @@ -1274,6 +1274,25 @@ sframe_xlate_do_gnu_window_save (struct sframe_xlate_ctx *xlate_ctx,
>     return SFRAME_XLATE_OK;
>   }
>   
> +/* Translate DW_CFA_GNU_window_save into SFrame context.
> +   DW_CFA_AARCH64_negate_ra_state is multiplexed with DW_CFA_GNU_window_save.
> +   Return SFRAME_XLATE_OK if success.  */
> +
> +static int
> +sframe_xlate_do_gnu_window_save (struct sframe_xlate_ctx *xlate_ctx,
> +				 struct cfi_insn_data *cfi_insn)
> +{
> +  unsigned char abi_arch = sframe_get_abi_arch ();
> +
> +  /* Translate DW_CFA_AARCH64_negate_ra_state into SFrame context.  */
> +  if (abi_arch == SFRAME_ABI_AARCH64_ENDIAN_BIG
> +      || abi_arch == SFRAME_ABI_AARCH64_ENDIAN_LITTLE)
> +    return sframe_xlate_do_aarch64_negate_ra_state (xlate_ctx, cfi_insn);
> +
> +  as_warn (_("skipping SFrame FDE due to .cfi_window_save"));
> +  return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
> +}
> +
>   /* Returns the DWARF call frame instruction name or fake CFI name for the
>      specified CFI opcode, or NULL if the value is not recognized.  */
>