[prev in list] [next in list] [prev in thread] [next in thread]
List: binutils
Subject: Re: [PATCH v2 8/9] gas: User readable warnings if SFrame FDE is not generated
From: Indu Bhagat <indu.bhagat () oracle ! com>
Date: 2024-02-29 7:39:04
Message-ID: 92ad665c-96b5-403b-860f-e344ac7ddf7d () oracle ! com
[Download RAW message or body]
On 2/23/24 09:07, 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:
>
> - skipping SFrame FDE due to .cfi_def_cfa specifying CFA base register
> other than SP or FP (<regno> instead of <SP-regno> or <FP-regno>)
I find that stating "<SP-regno> or <FP-regno>" is not necessary in the
warning. This information is identified unambiguously, given an ABI.
How about:
"skipping SFrame FDE due to .cfi_def_cfa defining CFA base reg to
<regno>" or similar ?
> - skipping SFrame FDE due to .cfi_def_cfa_register specifying CFA base
> register other than SP or FP (<regno> instead of <SP-regno> or
> <FP-regno>)
Same thought as above.
> - skipping SFrame FDE due to .cfi_def_cfa_offset without CFA base
> register in effect
> - skipping SFrame FDE due to .cfi_def_cfa_offset while CFA base register
> other than SP or FP in effect (<regno> instead of <SP-regno> or
> <FP-regno>)
Ditto.
> - skipping SFrame FDE due to .cfi_val_offset specifying {FP|RA} register
> (<regno>)
> - skipping SFrame FDE due to .cfi_remember_state without SFrame FRE
> state
I dont expect this warning to occur at all out in the field
(uhand-written asm with errors is the only case that comes to mind).
The testcase which triggers it simply happens to be just a testcase for
checking corner case handling.
WDYT about skipping this warning altogether ?
> - skipping SFrame FDE due to .cfi_register specifying {SP|FP|RA}
> register (<regno>)
> - skipping SFrame FDE due to non-default DWARF return column (<regno>
> instead of <DWARF-def-ret-col-regno>)
I think this can be simply "skipping SFrame FDE due to non-default
return addr reg <regno>". IMO, stating the default DWARF return address
register information in each warning msg does not add value.
Thanks
>
> 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.
>
> Reviewed-by: Andreas Krebbel <krebbel@linux.ibm.com>
> Signed-off-by: Jens Remus <jremus@linux.ibm.com>
> ---
> gas/gen-sframe.c | 96 ++++++++++++++-----
> 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, 79 insertions(+), 25 deletions(-)
>
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index 28b49a2a8425..339f4412ca05 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 +922,24 @@ 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 (sframe_ra_tracking_p ()
> + && (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 +1008,12 @@ 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 specifying CFA base "
> + "register other than SP or FP (%u instead of %u or %u)"),
> + cfi_insn->u.r, SFRAME_CFA_SP_REG, SFRAME_CFA_FP_REG);
> + 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 +1038,12 @@ 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 specifying "
> + "CFA base register other than SP or FP (%u instead of %u or %u)"),
> + cfi_insn->u.r, SFRAME_CFA_SP_REG, SFRAME_CFA_FP_REG);
> + 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 +1074,16 @@ 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 while CFA "
> + "base register other than SP or FP in effect (%u instead of %u or %u)"),
> + cur_fre->cfa_base_reg, SFRAME_CFA_SP_REG, SFRAME_CFA_FP_REG);
> + return SFRAME_XLATE_ERR_NOTREPRESENTED;
> + }
>
> return SFRAME_XLATE_OK;
> }
> @@ -1097,11 +1134,19 @@ sframe_xlate_do_val_offset (struct sframe_xlate_ctx \
> *xlate_ctx ATTRIBUTE_UNUSED, 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. */
> + {
> + as_warn (_("skipping SFrame FDE due to .cfi_val_offset specifying FP \
> register (%u)"), + SFRAME_CFA_FP_REG);
> + return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> + }
> #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. */
> + {
> + as_warn (_("skipping SFrame FDE due to .cfi_val_offset specifying RA \
> register (%u)"), + SFRAME_CFA_RA_REG);
> + return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> + }
> #endif
>
> /* Safe to skip. */
> @@ -1120,7 +1165,10 @@ 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 ();
> @@ -1307,7 +1355,12 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
> || cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG
> #endif
> || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
> - err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> + {
> + as_warn (_("skipping SFrame FDE due to .cfi_register specifying %s register \
> (%u)"), + sframe_register_name (cfi_insn->u.rr.reg1),
> + cfi_insn->u.rr.reg1);
> + err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> + }
> break;
> case DW_CFA_undefined:
> case DW_CFA_same_value:
> @@ -1315,21 +1368,19 @@ 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;
> }
>
> @@ -1346,7 +1397,8 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
> /* If the return column is not RIP, SFrame format cannot represent it. */
> 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 DWARF return column (%u \
> instead of %u)"), + xlate_ctx->dw_fde->return_column, \
> DWARF2_DEFAULT_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..9a46b016a9ba \
> 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 DWARF return column \(0 instead \
> of \d+\) #objdump: --sframe=.sframe
> #name: SFrame supports only default return column
> #...
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic