diff mbox series

[v3,09/15] gas: User readable warnings if SFrame FDE is not generated

Message ID 20240412144718.4191286-10-jremus@linux.ibm.com
State New
Headers
Series sframe: Enhancements to SFrame info generation |

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Commit Message

Jens Remus April 12, 2024, 2:47 p.m. UTC 
  The following generic warning message, which is printed whenever the
assembler skips generation of SFrame FDE, is not very helpful for the
user:

  skipping SFrame FDE due to DWARF CFI op <name> (0x<hexval>)

Whenever possible print meaningful warning messages, when the assembler
skips generation of SFrame FDE:

- skipping SFrame FDE due to .cfi_def_cfa defining non-SP/FP register
  <regno> as CFA base register
- skipping SFrame FDE due to .cfi_def_cfa_register defining non-SP/FP
  register <regno> as CFA base register
- skipping SFrame FDE due to .cfi_def_cfa_offset without CFA base
  register in effect
- skipping SFrame FDE due to .cfi_def_cfa_offset with non-SP/FP register
  <regno> as CFA base register in effect
- skipping SFrame FDE due to .cfi_val_offset specifying {FP|RA} register
- skipping SFrame FDE due to .cfi_remember_state without SFrame FRE
  state
- skipping SFrame FDE due to .cfi_register specifying {SP|FP|RA}
  register
- skipping SFrame FDE due to non-default return-address register <regno>

gas/
	* gen-sframe.h (SFRAME_FRE_BASE_REG_INVAL): New macro for
	invalid SFrame FRE CFA base register value of -1.
	* gen-sframe.c: User readable warnings if SFrame FDE is not
	generated.

gas/testsuite/
	* gas/cfi-sframe/common-empty-1.d: Update generic SFrame test
	case to updated warning message texts.
	* gas/cfi-sframe/common-empty-2.d: Likewise.
	* gas/cfi-sframe/common-empty-3.d: Likewise.

Reviewed-by: Andreas Krebbel <krebbel@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
---

Notes (jremus):
    Changes v2 -> v3:
    - Updated SFrame warning message texts as suggested by Indu, except for
      the .cfi_def_cfa[_register] ones. I think it would be helpful for the
      user to know that the issue is caused by a non-SP/FP register. But
      maybe that is because I am new to CFI and those that would actually
      debug the cause for these warnings would not need this extra
      information? Anyhow, Indu, if you still prefer your suggestions I
      would go with yours.
      The ".cfi_remember_state without SFrame FRE state" warning needs to
      remain, as there would otherwise not be any warning at all. The reason
      is that sframe_do_cfi_insn now expects any of its called CFI
      processing functions to emit a warning, if they return with an error,
      such as SFRAME_XLATE_ERR_NOTREPRESENTED. Silently skipping SFrame FDE
      does not seem an acceptable approach to me.
    - Do not test sframe_ra_tracking_p when determining the SFrame register
      name in sframe_register_name. The RA register name does not depend on
      whether RA tracking is used or not.
    - Corrected formatting of ChangeLog in commit message.

 gas/gen-sframe.c                              | 95 ++++++++++++++-----
 gas/gen-sframe.h                              |  2 +
 gas/testsuite/gas/cfi-sframe/common-empty-1.d |  2 +-
 gas/testsuite/gas/cfi-sframe/common-empty-2.d |  2 +-
 gas/testsuite/gas/cfi-sframe/common-empty-3.d |  2 +-
 5 files changed, 75 insertions(+), 28 deletions(-)

Comments

Indu Bhagat April 18, 2024, 8:33 p.m. UTC | #1 
On 4/12/24 07:47, Jens Remus wrote:
> The following generic warning message, which is printed whenever the
> assembler skips generation of SFrame FDE, is not very helpful for the
> user:
> 
>    skipping SFrame FDE due to DWARF CFI op <name> (0x<hexval>)
> 
> Whenever possible print meaningful warning messages, when the assembler
> skips generation of SFrame FDE:
> 

My intention below is to keep warning messages terse but useful.

> - skipping SFrame FDE due to .cfi_def_cfa defining non-SP/FP register
>    <regno> as CFA base register

.cfi_def_cfa _is_ used to specify the CFA base register. So I suggest we 
re-word this to following (and hence, removing the redundancy):

skipping SFrame FDE; non-SP/FP register <regno> in .cfi_def_cfa

or if (;) is unappetizing:

skipping SFrame FDE due to non-SP/FP register <regno> in .cfi_def_cfa

(replacing ; with "due to", if you prefer, applies to all comments below)

> - skipping SFrame FDE due to .cfi_def_cfa_register defining non-SP/FP
>    register <regno> as CFA base register

skipping SFrame FDE; non-SP/FP register <regno> in .cfi_def_cfa_register

> - skipping SFrame FDE due to .cfi_def_cfa_offset without CFA base
>    register in effect

skipping SFrame FDE; .cfi_def_cfa_offset specified when no CFA base 
register in effect

> - skipping SFrame FDE due to .cfi_def_cfa_offset with non-SP/FP register
>    <regno> as CFA base register in effect

I find this very confusing.  Can we not add this warning?  Such a case 
should not happen as we have handled the respective cases in 
sframe_xlate_do_def_cfa and sframe_xlate_do_def_cfa_register ?

> - skipping SFrame FDE due to .cfi_val_offset specifying {FP|RA} register

skipping SFrame FDE; FP/RA register <regno> in .cfi_val_offset

> - skipping SFrame FDE due to .cfi_remember_state without SFrame FRE
>    state

skipping SFrame FDE; .cfi_remember_state without prior SFrame FRE state

> - skipping SFrame FDE due to .cfi_register specifying {SP|FP|RA}
>    register

skipping SFrame FDE; FP/RA register <regno> in .cfi_register

> - skipping SFrame FDE due to non-default return-address register <regno>

skipping SFrame FDE; non-default RA register <regno>

> 
> gas/
> 	* gen-sframe.h (SFRAME_FRE_BASE_REG_INVAL): New macro for
> 	invalid SFrame FRE CFA base register value of -1.
> 	* gen-sframe.c: User readable warnings if SFrame FDE is not
> 	generated.
> 
> gas/testsuite/
> 	* gas/cfi-sframe/common-empty-1.d: Update generic SFrame test
> 	case to updated warning message texts.
> 	* gas/cfi-sframe/common-empty-2.d: Likewise.
> 	* gas/cfi-sframe/common-empty-3.d: Likewise.
> 
> Reviewed-by: Andreas Krebbel <krebbel@linux.ibm.com>
> Signed-off-by: Jens Remus <jremus@linux.ibm.com>
> ---
> 
> Notes (jremus):
>      Changes v2 -> v3:
>      - Updated SFrame warning message texts as suggested by Indu, except for
>        the .cfi_def_cfa[_register] ones. I think it would be helpful for the
>        user to know that the issue is caused by a non-SP/FP register. But
>        maybe that is because I am new to CFI and those that would actually
>        debug the cause for these warnings would not need this extra
>        information? Anyhow, Indu, if you still prefer your suggestions I
>        would go with yours.
>        The ".cfi_remember_state without SFrame FRE state" warning needs to
>        remain, as there would otherwise not be any warning at all. The reason
>        is that sframe_do_cfi_insn now expects any of its called CFI
>        processing functions to emit a warning, if they return with an error,
>        such as SFRAME_XLATE_ERR_NOTREPRESENTED. Silently skipping SFrame FDE
>        does not seem an acceptable approach to me.
>      - Do not test sframe_ra_tracking_p when determining the SFrame register
>        name in sframe_register_name. The RA register name does not depend on
>        whether RA tracking is used or not.
>      - Corrected formatting of ChangeLog in commit message.
> 
>   gas/gen-sframe.c                              | 95 ++++++++++++++-----
>   gas/gen-sframe.h                              |  2 +
>   gas/testsuite/gas/cfi-sframe/common-empty-1.d |  2 +-
>   gas/testsuite/gas/cfi-sframe/common-empty-2.d |  2 +-
>   gas/testsuite/gas/cfi-sframe/common-empty-3.d |  2 +-
>   5 files changed, 75 insertions(+), 28 deletions(-)
> 
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index f47f51c7a354..a3b6f75cfe85 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -867,7 +867,7 @@ sframe_row_entry_new (void)
>     struct sframe_row_entry *fre = XCNEW (struct sframe_row_entry);
>     /* Reset cfa_base_reg to -1.  A value of 0 will imply some valid register
>        for the supported arches.  */
> -  fre->cfa_base_reg = -1;
> +  fre->cfa_base_reg = SFRAME_FRE_BASE_REG_INVAL;
>     fre->merge_candidate = true;
>     /* Reset the mangled RA status bit to zero by default.  We will initialize it in
>        sframe_row_entry_initialize () with the sticky bit if set.  */
> @@ -922,6 +922,23 @@ sframe_row_entry_initialize (struct sframe_row_entry *cur_fre,
>     cur_fre->mangled_ra_p = prev_fre->mangled_ra_p;
>   }
>   
> +/* Return SFrame register name for SP, FP, and RA, or NULL if other.  */
> +
> +static const char *
> +sframe_register_name (unsigned int reg)
> +{
> +  if (reg == SFRAME_CFA_SP_REG)
> +    return "SP";
> +  else if (reg == SFRAME_CFA_FP_REG)
> +    return "FP";
> +#ifdef SFRAME_FRE_RA_TRACKING
> +  else if (reg == SFRAME_CFA_RA_REG)
> +    return "RA";
> +#endif
> +  else
> +    return NULL;
> +}
> +
>   /* Translate DW_CFA_advance_loc into SFrame context.
>      Return SFRAME_XLATE_OK if success.  */
>   
> @@ -990,7 +1007,12 @@ sframe_xlate_do_def_cfa (struct sframe_xlate_ctx *xlate_ctx,
>        SFrame stack trace info for the function.  */
>     if (cfi_insn->u.r != SFRAME_CFA_SP_REG
>         && cfi_insn->u.r != SFRAME_CFA_FP_REG)
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +    {
> +      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa defining "
> +		 "non-SP/FP register %u as CFA base register"),
> +	       cfi_insn->u.r);
> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +    }
>     sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
>     sframe_fre_set_cfa_offset (cur_fre, cfi_insn->u.ri.offset);
>     cur_fre->merge_candidate = false;
> @@ -1015,7 +1037,12 @@ sframe_xlate_do_def_cfa_register (struct sframe_xlate_ctx *xlate_ctx,
>        skip creating SFrame stack trace info for the function.  */
>     if (cfi_insn->u.r != SFRAME_CFA_SP_REG
>         && cfi_insn->u.r != SFRAME_CFA_FP_REG)
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +    {
> +      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_register defining "
> +		 "non-SP/FP register %u as CFA base register"),
> +	       cfi_insn->u.r);
> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +    }
>     sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
>     sframe_fre_set_cfa_offset (cur_fre, last_fre->cfa_offset);
>     cur_fre->merge_candidate = false;
> @@ -1046,7 +1073,16 @@ sframe_xlate_do_def_cfa_offset (struct sframe_xlate_ctx *xlate_ctx,
>         cur_fre->merge_candidate = false;
>       }
>     else
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED;
> +    {
> +      if (cur_fre->cfa_base_reg == SFRAME_FRE_BASE_REG_INVAL)
> +	as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset without "
> +		   "CFA base register in effect"));
> +      else
> +	as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset with "
> +		   "non-SP/FP register %u as CFA base register in effect"),
> +		 cur_fre->cfa_base_reg);
> +      return SFRAME_XLATE_ERR_NOTREPRESENTED;
> +    }
>   
>     return SFRAME_XLATE_OK;
>   }
> @@ -1096,13 +1132,16 @@ sframe_xlate_do_val_offset (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
>        register is not interesting (FP or RA reg), the current DW_CFA_val_offset
>        instruction can be safely skipped without sacrificing the asynchronicity of
>        stack trace information.  */
> -  if (cfi_insn->u.r == SFRAME_CFA_FP_REG)
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +  if (cfi_insn->u.r == SFRAME_CFA_FP_REG
>   #ifdef SFRAME_FRE_RA_TRACKING
> -  else if (sframe_ra_tracking_p ()
> -	   && cfi_insn->u.r == SFRAME_CFA_RA_REG)
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +      || (sframe_ra_tracking_p () && cfi_insn->u.r == SFRAME_CFA_RA_REG)
>   #endif
> +      )
> +    {
> +      as_warn (_("skipping SFrame FDE due to .cfi_val_offset specifying %s register"),
> +	       sframe_register_name (cfi_insn->u.r));
> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
> +    }
>   
>     /* Safe to skip.  */
>     return SFRAME_XLATE_OK;
> @@ -1124,7 +1163,11 @@ sframe_xlate_do_register (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
>         || (cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG)
>   #endif
>         || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
> -    return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
> +    {
> +      as_warn (_("skipping SFrame FDE due to .cfi_register specifying %s register"),
> +	       sframe_register_name (cfi_insn->u.rr.reg1));
> +      return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
> +    }
>   
>     /* Safe to skip.  */
>     return SFRAME_XLATE_OK;
> @@ -1142,7 +1185,10 @@ sframe_xlate_do_remember_state (struct sframe_xlate_ctx *xlate_ctx)
>        early with non-zero error code, this will cause no SFrame stack trace
>        info for the function involved.  */
>     if (!last_fre)
> -    return SFRAME_XLATE_ERR_INVAL;
> +    {
> +      as_warn (_("skipping SFrame FDE due to .cfi_remember_state without SFrame FRE state"));

"without SFrame FRE state" --> "without prior SFrame FRE state" ?

> +      return SFRAME_XLATE_ERR_INVAL;
> +    }
>   
>     if (!xlate_ctx->remember_fre)
>       xlate_ctx->remember_fre = sframe_row_entry_new ();
> @@ -1330,21 +1376,19 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
>       default:
>         /* 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)
> -    {
> -      const char *cfi_name = sframe_get_cfi_name (op);
> -
> -      if (!cfi_name)
> -	cfi_name = _("(unknown)");
> -      as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
> -	       cfi_name, op);
> +      {
> +	const char *cfi_name = sframe_get_cfi_name (op);
> +
> +	if (!cfi_name)
> +	  cfi_name = _("(unknown)");
> +	as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
> +		 cfi_name, op);
> +        err = SFRAME_XLATE_ERR_NOTREPRESENTED;

<>/GCC/gcc-upstream/gcc/contrib/check_GNU_style.py patch gives:

=== ERROR type #1: blocks of 8 spaces should be replaced with tabs (1 
error(s)) ===
gas/gen-sframe.c:1386:0:        err = SFRAME_XLATE_ERR_NOTREPRESENTED;

I dont think it is a must-be-used-script for binutils project, but for 
my commits I have used this script to keep code base aligned to same 
formatting style.

PS: Not all errors reported by the script need to be fixed.

> +      }
>       }
>   
> +  /* Any error will cause no SFrame FDE later.  The user has already been
> +     warned.  */
>     return err;
>   }
>   
> @@ -1361,7 +1405,8 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
>     /* SFrame format cannot represent a non-default DWARF return column reg.  */
>     if (xlate_ctx->dw_fde->return_column != DWARF2_DEFAULT_RETURN_COLUMN)
>       {
> -      as_warn (_("skipping SFrame FDE due to non-default DWARF return column"));
> +      as_warn (_("skipping SFrame FDE due to non-default return-address register %u"),
> +	       xlate_ctx->dw_fde->return_column);

return-address -> "return address" or even just RA.

>         return SFRAME_XLATE_ERR_NOTREPRESENTED;
>       }
>   
> diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
> index fbe2fd5d9368..8ed46dbb087b 100644
> --- a/gas/gen-sframe.h
> +++ b/gas/gen-sframe.h
> @@ -24,6 +24,8 @@
>   #define SFRAME_FRE_ELEM_LOC_REG		0
>   #define SFRAME_FRE_ELEM_LOC_STACK	1
>   
> +#define SFRAME_FRE_BASE_REG_INVAL	((unsigned int)-1)
> +
>   /* SFrame Frame Row Entry (FRE).
>   
>      A frame row entry is a slice of the frame and can be valid for a set of
> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-1.d b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> index d7756302b559..08731b069229 100644
> --- a/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
> @@ -1,5 +1,5 @@
>   #as: --gsframe
> -#warning: skipping SFrame FDE due to DWARF CFI op DW_CFA_remember_state \(0xa\)
> +#warning: skipping SFrame FDE due to \.cfi_remember_state without SFrame FRE state
>   #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 20282c7854e8..e759cddfcc20 100644
> --- a/gas/testsuite/gas/cfi-sframe/common-empty-2.d
> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
> @@ -1,5 +1,5 @@
>   #as: --gsframe
> -#warning: skipping SFrame FDE due to DWARF CFI op DW_CFA_def_cfa_offset \(0xe\)
> +#warning: skipping SFrame FDE due to \.cfi_def_cfa_offset without CFA base register in effect
>   #objdump: --sframe=.sframe
>   #name: SFrame supports only FP/SP based CFA
>   #...
> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-3.d b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
> index d17521dd88ea..5cc37d5ff440 100644
> --- a/gas/testsuite/gas/cfi-sframe/common-empty-3.d
> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
> @@ -1,5 +1,5 @@
>   #as: --gsframe
> -#warning: skipping SFrame FDE due to non-default DWARF return column
> +#warning: skipping SFrame FDE due to non-default return-address register 0
>   #objdump: --sframe=.sframe
>   #name: SFrame supports only default return column
>   #...
Jens Remus May 3, 2024, 12:30 p.m. UTC | #2 
Am 18.04.2024 um 22:33 schrieb Indu Bhagat:
> On 4/12/24 07:47, Jens Remus wrote:
>> The following generic warning message, which is printed whenever the
>> assembler skips generation of SFrame FDE, is not very helpful for the
>> user:
>>
>>    skipping SFrame FDE due to DWARF CFI op <name> (0x<hexval>)
>>
>> Whenever possible print meaningful warning messages, when the assembler
>> skips generation of SFrame FDE:
>>
> 
> My intention below is to keep warning messages terse but useful.
> 
>> - skipping SFrame FDE due to .cfi_def_cfa defining non-SP/FP register
>>    <regno> as CFA base register
> 
> .cfi_def_cfa _is_ used to specify the CFA base register. So I suggest we 
> re-word this to following (and hence, removing the redundancy):
> 
> skipping SFrame FDE; non-SP/FP register <regno> in .cfi_def_cfa

Done.

> 
> or if (;) is unappetizing:
> 
> skipping SFrame FDE due to non-SP/FP register <regno> in .cfi_def_cfa
> 
> (replacing ; with "due to", if you prefer, applies to all comments below)

I like the terse format. Especially as it saves some characters for the longer reason descriptions.

> 
>> - skipping SFrame FDE due to .cfi_def_cfa_register defining non-SP/FP
>>    register <regno> as CFA base register
> 
> skipping SFrame FDE; non-SP/FP register <regno> in .cfi_def_cfa_register

Done.

> 
>> - skipping SFrame FDE due to .cfi_def_cfa_offset without CFA base
>>    register in effect
> 
> skipping SFrame FDE; .cfi_def_cfa_offset specified when no CFA base 
> register in effect

"when no" or "without" (see "without prior SFrame FRE state" below)?

> 
>> - skipping SFrame FDE due to .cfi_def_cfa_offset with non-SP/FP register
>>    <regno> as CFA base register in effect
> 
> I find this very confusing.  Can we not add this warning?  Such a case 
> should not happen as we have handled the respective cases in 
> sframe_xlate_do_def_cfa and sframe_xlate_do_def_cfa_register ?

Done. I finally got the point. I have added the following comment as explanation:

/* No CFA base register in effect.  Non-SP/FP CFA base register should
    not occur, as sframe_xlate_do_def_cfa[_register] would detect this.  */

> 
>> - skipping SFrame FDE due to .cfi_val_offset specifying {FP|RA} register
> 
> skipping SFrame FDE; FP/RA register <regno> in .cfi_val_offset

Done.

> 
>> - skipping SFrame FDE due to .cfi_remember_state without SFrame FRE
>>    state
> 
> skipping SFrame FDE; .cfi_remember_state without prior SFrame FRE state

Done.

> 
>> - skipping SFrame FDE due to .cfi_register specifying {SP|FP|RA}
>>    register
> 
> skipping SFrame FDE; FP/RA register <regno> in .cfi_register

Done.

> 
>> - skipping SFrame FDE due to non-default return-address register <regno>
> 
> skipping SFrame FDE; non-default RA register <regno>

Done. Using the abbreviation "RA" instead of "return address" aligns well with the other warnings.


For consistency I have changed the following SFrame warnings as well:

skipping SFrame FDE; CFI insn <name> (<hexval>)

skipping SFrame FDE; FP without RA on stack

skipping SFrame FDE; .cfi_window_save

> 
>>
>> gas/
>>     * gen-sframe.h (SFRAME_FRE_BASE_REG_INVAL): New macro for
>>     invalid SFrame FRE CFA base register value of -1.
>>     * gen-sframe.c: User readable warnings if SFrame FDE is not
>>     generated.
>>
>> gas/testsuite/
>>     * gas/cfi-sframe/common-empty-1.d: Update generic SFrame test
>>     case to updated warning message texts.
>>     * gas/cfi-sframe/common-empty-2.d: Likewise.
>>     * gas/cfi-sframe/common-empty-3.d: Likewise.
>>
>> Reviewed-by: Andreas Krebbel <krebbel@linux.ibm.com>
>> Signed-off-by: Jens Remus <jremus@linux.ibm.com>
>> ---
>>
>> Notes (jremus):
>>      Changes v2 -> v3:
>>      - Updated SFrame warning message texts as suggested by Indu, 
>> except for
>>        the .cfi_def_cfa[_register] ones. I think it would be helpful 
>> for the
>>        user to know that the issue is caused by a non-SP/FP register. But
>>        maybe that is because I am new to CFI and those that would 
>> actually
>>        debug the cause for these warnings would not need this extra
>>        information? Anyhow, Indu, if you still prefer your suggestions I
>>        would go with yours.
>>        The ".cfi_remember_state without SFrame FRE state" warning 
>> needs to
>>        remain, as there would otherwise not be any warning at all. The 
>> reason
>>        is that sframe_do_cfi_insn now expects any of its called CFI
>>        processing functions to emit a warning, if they return with an 
>> error,
>>        such as SFRAME_XLATE_ERR_NOTREPRESENTED. Silently skipping 
>> SFrame FDE
>>        does not seem an acceptable approach to me.
>>      - Do not test sframe_ra_tracking_p when determining the SFrame 
>> register
>>        name in sframe_register_name. The RA register name does not 
>> depend on
>>        whether RA tracking is used or not.
>>      - Corrected formatting of ChangeLog in commit message.
>>
>>   gas/gen-sframe.c                              | 95 ++++++++++++++-----
>>   gas/gen-sframe.h                              |  2 +
>>   gas/testsuite/gas/cfi-sframe/common-empty-1.d |  2 +-
>>   gas/testsuite/gas/cfi-sframe/common-empty-2.d |  2 +-
>>   gas/testsuite/gas/cfi-sframe/common-empty-3.d |  2 +-
>>   5 files changed, 75 insertions(+), 28 deletions(-)
>>
>> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
>> index f47f51c7a354..a3b6f75cfe85 100644
>> --- a/gas/gen-sframe.c
>> +++ b/gas/gen-sframe.c
>> @@ -867,7 +867,7 @@ sframe_row_entry_new (void)
>>     struct sframe_row_entry *fre = XCNEW (struct sframe_row_entry);
>>     /* Reset cfa_base_reg to -1.  A value of 0 will imply some valid 
>> register
>>        for the supported arches.  */
>> -  fre->cfa_base_reg = -1;
>> +  fre->cfa_base_reg = SFRAME_FRE_BASE_REG_INVAL;
>>     fre->merge_candidate = true;
>>     /* Reset the mangled RA status bit to zero by default.  We will 
>> initialize it in
>>        sframe_row_entry_initialize () with the sticky bit if set.  */
>> @@ -922,6 +922,23 @@ sframe_row_entry_initialize (struct 
>> sframe_row_entry *cur_fre,
>>     cur_fre->mangled_ra_p = prev_fre->mangled_ra_p;
>>   }
>> +/* Return SFrame register name for SP, FP, and RA, or NULL if other.  */
>> +
>> +static const char *
>> +sframe_register_name (unsigned int reg)
>> +{
>> +  if (reg == SFRAME_CFA_SP_REG)
>> +    return "SP";
>> +  else if (reg == SFRAME_CFA_FP_REG)
>> +    return "FP";
>> +#ifdef SFRAME_FRE_RA_TRACKING
>> +  else if (reg == SFRAME_CFA_RA_REG)
>> +    return "RA";
>> +#endif
>> +  else
>> +    return NULL;
>> +}
>> +
>>   /* Translate DW_CFA_advance_loc into SFrame context.
>>      Return SFRAME_XLATE_OK if success.  */
>> @@ -990,7 +1007,12 @@ sframe_xlate_do_def_cfa (struct sframe_xlate_ctx 
>> *xlate_ctx,
>>        SFrame stack trace info for the function.  */
>>     if (cfi_insn->u.r != SFRAME_CFA_SP_REG
>>         && cfi_insn->u.r != SFRAME_CFA_FP_REG)
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +    {
>> +      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa defining "
>> +         "non-SP/FP register %u as CFA base register"),
>> +           cfi_insn->u.r);
>> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +    }
>>     sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
>>     sframe_fre_set_cfa_offset (cur_fre, cfi_insn->u.ri.offset);
>>     cur_fre->merge_candidate = false;
>> @@ -1015,7 +1037,12 @@ sframe_xlate_do_def_cfa_register (struct 
>> sframe_xlate_ctx *xlate_ctx,
>>        skip creating SFrame stack trace info for the function.  */
>>     if (cfi_insn->u.r != SFRAME_CFA_SP_REG
>>         && cfi_insn->u.r != SFRAME_CFA_FP_REG)
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +    {
>> +      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_register 
>> defining "
>> +         "non-SP/FP register %u as CFA base register"),
>> +           cfi_insn->u.r);
>> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +    }
>>     sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
>>     sframe_fre_set_cfa_offset (cur_fre, last_fre->cfa_offset);
>>     cur_fre->merge_candidate = false;
>> @@ -1046,7 +1073,16 @@ sframe_xlate_do_def_cfa_offset (struct 
>> sframe_xlate_ctx *xlate_ctx,
>>         cur_fre->merge_candidate = false;
>>       }
>>     else
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED;
>> +    {
>> +      if (cur_fre->cfa_base_reg == SFRAME_FRE_BASE_REG_INVAL)
>> +    as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset without "
>> +           "CFA base register in effect"));
>> +      else
>> +    as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset with "
>> +           "non-SP/FP register %u as CFA base register in effect"),
>> +         cur_fre->cfa_base_reg);
>> +      return SFRAME_XLATE_ERR_NOTREPRESENTED;
>> +    }
>>     return SFRAME_XLATE_OK;
>>   }
>> @@ -1096,13 +1132,16 @@ sframe_xlate_do_val_offset (struct 
>> sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
>>        register is not interesting (FP or RA reg), the current 
>> DW_CFA_val_offset
>>        instruction can be safely skipped without sacrificing the 
>> asynchronicity of
>>        stack trace information.  */
>> -  if (cfi_insn->u.r == SFRAME_CFA_FP_REG)
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +  if (cfi_insn->u.r == SFRAME_CFA_FP_REG
>>   #ifdef SFRAME_FRE_RA_TRACKING
>> -  else if (sframe_ra_tracking_p ()
>> -       && cfi_insn->u.r == SFRAME_CFA_RA_REG)
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +      || (sframe_ra_tracking_p () && cfi_insn->u.r == SFRAME_CFA_RA_REG)
>>   #endif
>> +      )
>> +    {
>> +      as_warn (_("skipping SFrame FDE due to .cfi_val_offset 
>> specifying %s register"),
>> +           sframe_register_name (cfi_insn->u.r));
>> +      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
>> +    }
>>     /* Safe to skip.  */
>>     return SFRAME_XLATE_OK;
>> @@ -1124,7 +1163,11 @@ sframe_xlate_do_register (struct 
>> sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
>>         || (cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG)
>>   #endif
>>         || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
>> -    return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
>> +    {
>> +      as_warn (_("skipping SFrame FDE due to .cfi_register specifying 
>> %s register"),
>> +           sframe_register_name (cfi_insn->u.rr.reg1));
>> +      return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
>> +    }
>>     /* Safe to skip.  */
>>     return SFRAME_XLATE_OK;
>> @@ -1142,7 +1185,10 @@ sframe_xlate_do_remember_state (struct 
>> sframe_xlate_ctx *xlate_ctx)
>>        early with non-zero error code, this will cause no SFrame stack 
>> trace
>>        info for the function involved.  */
>>     if (!last_fre)
>> -    return SFRAME_XLATE_ERR_INVAL;
>> +    {
>> +      as_warn (_("skipping SFrame FDE due to .cfi_remember_state 
>> without SFrame FRE state"));
> 
> "without SFrame FRE state" --> "without prior SFrame FRE state" ?
> 
>> +      return SFRAME_XLATE_ERR_INVAL;
>> +    }
>>     if (!xlate_ctx->remember_fre)
>>       xlate_ctx->remember_fre = sframe_row_entry_new ();
>> @@ -1330,21 +1376,19 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx 
>> *xlate_ctx,
>>       default:
>>         /* 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)
>> -    {
>> -      const char *cfi_name = sframe_get_cfi_name (op);
>> -
>> -      if (!cfi_name)
>> -    cfi_name = _("(unknown)");
>> -      as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
>> -           cfi_name, op);
>> +      {
>> +    const char *cfi_name = sframe_get_cfi_name (op);
>> +
>> +    if (!cfi_name)
>> +      cfi_name = _("(unknown)");
>> +    as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
>> +         cfi_name, op);
>> +        err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> 
> <>/GCC/gcc-upstream/gcc/contrib/check_GNU_style.py patch gives:
> 
> === ERROR type #1: blocks of 8 spaces should be replaced with tabs (1 
> error(s)) ===
> gas/gen-sframe.c:1386:0:        err = SFRAME_XLATE_ERR_NOTREPRESENTED;

Corrected.

> 
> I dont think it is a must-be-used-script for binutils project, but for 
> my commits I have used this script to keep code base aligned to same 
> formatting style.

Thanks for sharing! That is really helful!

> 
> PS: Not all errors reported by the script need to be fixed.
> 
>> +      }
>>       }
>> +  /* Any error will cause no SFrame FDE later.  The user has already 
>> been
>> +     warned.  */
>>     return err;
>>   }
>> @@ -1361,7 +1405,8 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
>>     /* SFrame format cannot represent a non-default DWARF return 
>> column reg.  */
>>     if (xlate_ctx->dw_fde->return_column != DWARF2_DEFAULT_RETURN_COLUMN)
>>       {
>> -      as_warn (_("skipping SFrame FDE due to non-default DWARF return 
>> column"));
>> +      as_warn (_("skipping SFrame FDE due to non-default 
>> return-address register %u"),
>> +           xlate_ctx->dw_fde->return_column);
> 
> return-address -> "return address" or even just RA.
> 
>>         return SFRAME_XLATE_ERR_NOTREPRESENTED;
>>       }
>> diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
>> index fbe2fd5d9368..8ed46dbb087b 100644
>> --- a/gas/gen-sframe.h
>> +++ b/gas/gen-sframe.h
>> @@ -24,6 +24,8 @@
>>   #define SFRAME_FRE_ELEM_LOC_REG        0
>>   #define SFRAME_FRE_ELEM_LOC_STACK    1
>> +#define SFRAME_FRE_BASE_REG_INVAL    ((unsigned int)-1)
>> +
>>   /* SFrame Frame Row Entry (FRE).
>>      A frame row entry is a slice of the frame and can be valid for a 
>> set of
>> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-1.d 
>> b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
>> index d7756302b559..08731b069229 100644
>> --- a/gas/testsuite/gas/cfi-sframe/common-empty-1.d
>> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
>> @@ -1,5 +1,5 @@
>>   #as: --gsframe
>> -#warning: skipping SFrame FDE due to DWARF CFI op 
>> DW_CFA_remember_state \(0xa\)
>> +#warning: skipping SFrame FDE due to \.cfi_remember_state without 
>> SFrame FRE state
>>   #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 20282c7854e8..e759cddfcc20 100644
>> --- a/gas/testsuite/gas/cfi-sframe/common-empty-2.d
>> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
>> @@ -1,5 +1,5 @@
>>   #as: --gsframe
>> -#warning: skipping SFrame FDE due to DWARF CFI op 
>> DW_CFA_def_cfa_offset \(0xe\)
>> +#warning: skipping SFrame FDE due to \.cfi_def_cfa_offset without CFA 
>> base register in effect
>>   #objdump: --sframe=.sframe
>>   #name: SFrame supports only FP/SP based CFA
>>   #...
>> diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-3.d 
>> b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
>> index d17521dd88ea..5cc37d5ff440 100644
>> --- a/gas/testsuite/gas/cfi-sframe/common-empty-3.d
>> +++ b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
>> @@ -1,5 +1,5 @@
>>   #as: --gsframe
>> -#warning: skipping SFrame FDE due to non-default DWARF return column
>> +#warning: skipping SFrame FDE due to non-default return-address 
>> register 0
>>   #objdump: --sframe=.sframe
>>   #name: SFrame supports only default return column
>>   #...
> 

Regards,
Jens
Indu Bhagat May 3, 2024, 11:41 p.m. UTC | #3 
On 5/3/24 05:30, Jens Remus wrote:
>>
>>> - skipping SFrame FDE due to .cfi_def_cfa_offset without CFA base
>>>    register in effect
>>
>> skipping SFrame FDE; .cfi_def_cfa_offset specified when no CFA base 
>> register in effect
> 
> "when no" or "without" (see "without prior SFrame FRE state" below)?

I think "without" is better.
diff mbox series

Patch

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index f47f51c7a354..a3b6f75cfe85 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -867,7 +867,7 @@  sframe_row_entry_new (void)
   struct sframe_row_entry *fre = XCNEW (struct sframe_row_entry);
   /* Reset cfa_base_reg to -1.  A value of 0 will imply some valid register
      for the supported arches.  */
-  fre->cfa_base_reg = -1;
+  fre->cfa_base_reg = SFRAME_FRE_BASE_REG_INVAL;
   fre->merge_candidate = true;
   /* Reset the mangled RA status bit to zero by default.  We will initialize it in
      sframe_row_entry_initialize () with the sticky bit if set.  */
@@ -922,6 +922,23 @@  sframe_row_entry_initialize (struct sframe_row_entry *cur_fre,
   cur_fre->mangled_ra_p = prev_fre->mangled_ra_p;
 }
 
+/* Return SFrame register name for SP, FP, and RA, or NULL if other.  */
+
+static const char *
+sframe_register_name (unsigned int reg)
+{
+  if (reg == SFRAME_CFA_SP_REG)
+    return "SP";
+  else if (reg == SFRAME_CFA_FP_REG)
+    return "FP";
+#ifdef SFRAME_FRE_RA_TRACKING
+  else if (reg == SFRAME_CFA_RA_REG)
+    return "RA";
+#endif
+  else
+    return NULL;
+}
+
 /* Translate DW_CFA_advance_loc into SFrame context.
    Return SFRAME_XLATE_OK if success.  */
 
@@ -990,7 +1007,12 @@  sframe_xlate_do_def_cfa (struct sframe_xlate_ctx *xlate_ctx,
      SFrame stack trace info for the function.  */
   if (cfi_insn->u.r != SFRAME_CFA_SP_REG
       && cfi_insn->u.r != SFRAME_CFA_FP_REG)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    {
+      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa defining "
+		 "non-SP/FP register %u as CFA base register"),
+	       cfi_insn->u.r);
+      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    }
   sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
   sframe_fre_set_cfa_offset (cur_fre, cfi_insn->u.ri.offset);
   cur_fre->merge_candidate = false;
@@ -1015,7 +1037,12 @@  sframe_xlate_do_def_cfa_register (struct sframe_xlate_ctx *xlate_ctx,
      skip creating SFrame stack trace info for the function.  */
   if (cfi_insn->u.r != SFRAME_CFA_SP_REG
       && cfi_insn->u.r != SFRAME_CFA_FP_REG)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    {
+      as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_register defining "
+		 "non-SP/FP register %u as CFA base register"),
+	       cfi_insn->u.r);
+      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    }
   sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
   sframe_fre_set_cfa_offset (cur_fre, last_fre->cfa_offset);
   cur_fre->merge_candidate = false;
@@ -1046,7 +1073,16 @@  sframe_xlate_do_def_cfa_offset (struct sframe_xlate_ctx *xlate_ctx,
       cur_fre->merge_candidate = false;
     }
   else
-    return SFRAME_XLATE_ERR_NOTREPRESENTED;
+    {
+      if (cur_fre->cfa_base_reg == SFRAME_FRE_BASE_REG_INVAL)
+	as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset without "
+		   "CFA base register in effect"));
+      else
+	as_warn (_("skipping SFrame FDE due to .cfi_def_cfa_offset with "
+		   "non-SP/FP register %u as CFA base register in effect"),
+		 cur_fre->cfa_base_reg);
+      return SFRAME_XLATE_ERR_NOTREPRESENTED;
+    }
 
   return SFRAME_XLATE_OK;
 }
@@ -1096,13 +1132,16 @@  sframe_xlate_do_val_offset (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
      register is not interesting (FP or RA reg), the current DW_CFA_val_offset
      instruction can be safely skipped without sacrificing the asynchronicity of
      stack trace information.  */
-  if (cfi_insn->u.r == SFRAME_CFA_FP_REG)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+  if (cfi_insn->u.r == SFRAME_CFA_FP_REG
 #ifdef SFRAME_FRE_RA_TRACKING
-  else if (sframe_ra_tracking_p ()
-	   && cfi_insn->u.r == SFRAME_CFA_RA_REG)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+      || (sframe_ra_tracking_p () && cfi_insn->u.r == SFRAME_CFA_RA_REG)
 #endif
+      )
+    {
+      as_warn (_("skipping SFrame FDE due to .cfi_val_offset specifying %s register"),
+	       sframe_register_name (cfi_insn->u.r));
+      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    }
 
   /* Safe to skip.  */
   return SFRAME_XLATE_OK;
@@ -1124,7 +1163,11 @@  sframe_xlate_do_register (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
       || (cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG)
 #endif
       || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
+    {
+      as_warn (_("skipping SFrame FDE due to .cfi_register specifying %s register"),
+	       sframe_register_name (cfi_insn->u.rr.reg1));
+      return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
+    }
 
   /* Safe to skip.  */
   return SFRAME_XLATE_OK;
@@ -1142,7 +1185,10 @@  sframe_xlate_do_remember_state (struct sframe_xlate_ctx *xlate_ctx)
      early with non-zero error code, this will cause no SFrame stack trace
      info for the function involved.  */
   if (!last_fre)
-    return SFRAME_XLATE_ERR_INVAL;
+    {
+      as_warn (_("skipping SFrame FDE due to .cfi_remember_state without SFrame FRE state"));
+      return SFRAME_XLATE_ERR_INVAL;
+    }
 
   if (!xlate_ctx->remember_fre)
     xlate_ctx->remember_fre = sframe_row_entry_new ();
@@ -1330,21 +1376,19 @@  sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
     default:
       /* 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)
-    {
-      const char *cfi_name = sframe_get_cfi_name (op);
-
-      if (!cfi_name)
-	cfi_name = _("(unknown)");
-      as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
-	       cfi_name, op);
+      {
+	const char *cfi_name = sframe_get_cfi_name (op);
+
+	if (!cfi_name)
+	  cfi_name = _("(unknown)");
+	as_warn (_("skipping SFrame FDE due to DWARF CFI op %s (%#x)"),
+		 cfi_name, op);
+        err = SFRAME_XLATE_ERR_NOTREPRESENTED;
+      }
     }
 
+  /* Any error will cause no SFrame FDE later.  The user has already been
+     warned.  */
   return err;
 }
 
@@ -1361,7 +1405,8 @@  sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
   /* SFrame format cannot represent a non-default DWARF return column reg.  */
   if (xlate_ctx->dw_fde->return_column != DWARF2_DEFAULT_RETURN_COLUMN)
     {
-      as_warn (_("skipping SFrame FDE due to non-default DWARF return column"));
+      as_warn (_("skipping SFrame FDE due to non-default return-address register %u"),
+	       xlate_ctx->dw_fde->return_column);
       return SFRAME_XLATE_ERR_NOTREPRESENTED;
     }
 
diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
index fbe2fd5d9368..8ed46dbb087b 100644
--- a/gas/gen-sframe.h
+++ b/gas/gen-sframe.h
@@ -24,6 +24,8 @@ 
 #define SFRAME_FRE_ELEM_LOC_REG		0
 #define SFRAME_FRE_ELEM_LOC_STACK	1
 
+#define SFRAME_FRE_BASE_REG_INVAL	((unsigned int)-1)
+
 /* SFrame Frame Row Entry (FRE).
 
    A frame row entry is a slice of the frame and can be valid for a set of
diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-1.d b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
index d7756302b559..08731b069229 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-1.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
@@ -1,5 +1,5 @@ 
 #as: --gsframe
-#warning: skipping SFrame FDE due to DWARF CFI op DW_CFA_remember_state \(0xa\)
+#warning: skipping SFrame FDE due to \.cfi_remember_state without SFrame FRE state
 #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 20282c7854e8..e759cddfcc20 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-2.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
@@ -1,5 +1,5 @@ 
 #as: --gsframe
-#warning: skipping SFrame FDE due to DWARF CFI op DW_CFA_def_cfa_offset \(0xe\)
+#warning: skipping SFrame FDE due to \.cfi_def_cfa_offset without CFA base register in effect
 #objdump: --sframe=.sframe
 #name: SFrame supports only FP/SP based CFA
 #...
diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-3.d b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
index d17521dd88ea..5cc37d5ff440 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-3.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
@@ -1,5 +1,5 @@ 
 #as: --gsframe
-#warning: skipping SFrame FDE due to non-default DWARF return column
+#warning: skipping SFrame FDE due to non-default return-address register 0
 #objdump: --sframe=.sframe
 #name: SFrame supports only default return column
 #...