Re: [PATCH] gas: sframe: warn when skipping SFrame FDE generation

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

On 1/10/24 3:11 PM, Indu Bhagat wrote:
> Fix PR gas/31213.
> 
> gas/
> 	PR gas/31213
>          * gen-sframe.c (sframe_do_cfi_insn): Add new warning.
> 
> gas/testsuite/
> 	* gas/cfi-sframe/common-empty-1.d: Test the new warning as well.
> 	* gas/cfi-sframe/common-empty-2.d: Likewise.
> ---
>   gas/gen-sframe.c                              | 34 ++++++++++++-------
>   gas/testsuite/gas/cfi-sframe/common-empty-1.d |  1 +
>   gas/testsuite/gas/cfi-sframe/common-empty-2.d |  1 +
>   3 files changed, 23 insertions(+), 13 deletions(-)
> 

Committed.

> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index 3c212f3a882..75781fc8ccb 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -1247,25 +1247,33 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
>       case DW_CFA_GNU_window_save:
>         err = sframe_xlate_do_gnu_window_save (xlate_ctx, cfi_insn);
>         break;
> +    /* Other CFI opcodes are not processed at this time.
> +       These do not impact the coverage of the basic stack tracing
> +       information as conveyed in the SFrame format.
> +	- DW_CFA_register,
> +	- etc.  */
> +    case DW_CFA_register:
> +      if (cfi_insn->u.rr.reg1 == SFRAME_CFA_SP_REG
> +#ifdef SFRAME_FRE_RA_TRACKING
> +	  || cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG
> +#endif
> +	  || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
> +	err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> +      break;
>       case DW_CFA_undefined:
>       case DW_CFA_same_value:
>         break;
>       default:
> -      {
> -	/* Other CFI opcodes are not processed at this time.
> -	   These do not impact the coverage of the basic stack tracing
> -	   information as conveyed in the SFrame format.
> -	    - DW_CFA_register,
> -	    - ...
> -
> -	   Following skipped operations do, however, impact the asynchronicity:
> -	     - CFI_escape  */
> -
> -	err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> -	// printf (_("SFrame Unsupported or unknown Dwarf CFI number: %#x\n"), op);
> -      }
> +      /* Following skipped operations do, however, impact the asynchronicity:
> +	  - CFI_escape.  */
> +      err = SFRAME_XLATE_ERR_NOTREPRESENTED;
>       }
>   
> +  /* An error here will cause no SFrame FDE later.  Warn the user because this
> +     will affect the overall coverage and hence, asynchronicity.  */
> +  if (err)
> +    as_warn (_("skipping SFrame FDE due to DWARF CFI op %#x"), op);
> +
>     return err;
>   }
>   
> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-1.d b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> index 141922517f0..b133b15b051 100644
> --- a/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> @@ -1,4 +1,5 @@
>   #as: --gsframe
> +#warning: skipping SFrame FDE due to DWARF CFI op 0xa
>   #objdump: --sframe=.sframe
>   #name: Uninteresting cfi directives generate an empty SFrame section
>   #...
> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-2.d b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
> index ab8de0b8afa..c5bc8594f1b 100644
> --- a/gas/testsuite/gas/cfi-sframe/common-empty-2.d
> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
> @@ -1,4 +1,5 @@
>   #as: --gsframe
> +#warning: skipping SFrame FDE due to DWARF CFI op 0xe
>   #objdump: --sframe=.sframe
>   #name: SFrame supports only FP/SP based CFA
>   #...
>