[PATCH 2/5] gas: disable SFrame warnings if default-enabled
Sam James
sam@gentoo.org
Mon Aug 18 14:24:21 GMT 2025
Sam James <sam@gentoo.org> writes:
> When bootstrapping Binutils in packaging, I saw:
> ```
> {standard input}: Assembler messages:
> {standard input}: Warning: no SFrame FDE emitted; non-SP/FP register 10 in .cfi_def_cfa
> {standard input}: Warning: no SFrame FDE emitted; .cfi_escape with op (0xf)
> [...]
> FAIL: bootstrap with strip
> ```
>
> Disable all the "no SFrame FDE emitted" warnings if SFrames are default-enabled:
> they will still appear with explicit --gsframe=yes. For distributions to
> deploy default-enabled SFrames, SFrames need to be opportunistic, which
> means not creating a lot of noise in build logs or aborting the build
> when SFrames cannot be generated (unless --gsframe is passed explicitly,
> of course).
>
> Note that this commit does not preclude the possibility of us emitting
> a warning in the default-enabled case in future if it's merited, just it
> doesn't seem we ought to in these cases.
Prompted by doko asking about this: the big issue (or non-issue with the
change) is SFrames currently can't handle some common patterns emitted
by GCC, see
https://sourceware.org/binutils/wiki/sframe/sframev3todo#Make_support_for_topmost_frames_more_flexible.
The warning approach can be adjusted as circumstances change in future.
>
> gas/
> PR gas/33126
> * gen-sframe.c (sframe_xlate_do_def_cfa): Disable warning.
> (sframe_xlate_do_def_cfa_register): Ditto.
> (sframe_xlate_do_def_cfa_offset): Ditto.
> (sframe_xlate_do_val_offset): Ditto.
> (sframe_xlate_do_register): Ditto.
> (sframe_xlate_do_remember_state): Ditto.
> (sframe_xlate_do_aarch64_negate_ra_state_with_pc): Ditto.
> (sframe_xlate_do_gnu_window_save): Ditto.
> (sframe_xlate_do_escape_expr): Ditto.
> (sframe_xlate_do_cfi_escape): Ditto.
> (sframe_xlate_do_cfi_undefined): Ditto.
> (sframe_do_cfi_insn): Ditto.
> (sframe_do_fde): Ditto.
> * gen-sframe.h (sframe_as_warn): New macro.
> ---
> gas/gen-sframe.c | 60 +++++++++++++++++++++++++-----------------------
> gas/gen-sframe.h | 8 +++++++
> 2 files changed, 39 insertions(+), 29 deletions(-)
>
> diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
> index d082b974be3..f5bd5ede1b4 100644
> --- a/gas/gen-sframe.c
> +++ b/gas/gen-sframe.c
> @@ -1022,9 +1022,9 @@ sframe_xlate_do_def_cfa (struct sframe_xlate_ctx *xlate_ctx,
> if (cfi_insn->u.ri.reg != SFRAME_CFA_SP_REG
> && cfi_insn->u.ri.reg != SFRAME_CFA_FP_REG)
> {
> - as_warn (_("no SFrame FDE emitted; "
> - "non-SP/FP register %u in .cfi_def_cfa"),
> - cfi_insn->u.ri.reg);
> + sframe_as_warn (_("no SFrame FDE emitted; "
> + "non-SP/FP register %u in .cfi_def_cfa"),
> + cfi_insn->u.ri.reg);
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
> sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.ri.reg);
> @@ -1052,9 +1052,9 @@ sframe_xlate_do_def_cfa_register (struct sframe_xlate_ctx *xlate_ctx,
> if (cfi_insn->u.r != SFRAME_CFA_SP_REG
> && cfi_insn->u.r != SFRAME_CFA_FP_REG)
> {
> - as_warn (_("no SFrame FDE emitted; "
> - "non-SP/FP register %u in .cfi_def_cfa_register"),
> - cfi_insn->u.r);
> + sframe_as_warn (_("no SFrame FDE emitted; "
> + "non-SP/FP register %u in .cfi_def_cfa_register"),
> + cfi_insn->u.r);
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
> sframe_fre_set_cfa_base_reg (cur_fre, cfi_insn->u.r);
> @@ -1092,8 +1092,8 @@ sframe_xlate_do_def_cfa_offset (struct sframe_xlate_ctx *xlate_ctx,
> {
> /* 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. */
> - as_warn (_("no SFrame FDE emitted; "
> - ".cfi_def_cfa_offset without CFA base register in effect"));
> + sframe_as_warn (_("no SFrame FDE emitted; "
> + ".cfi_def_cfa_offset without CFA base register in effect"));
> return SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
>
> @@ -1157,9 +1157,9 @@ sframe_xlate_do_val_offset (const struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_U
> || (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
> && cfi_insn->u.ri.offset != SFRAME_S390X_SP_VAL_OFFSET))))
> {
> - as_warn (_("no SFrame FDE emitted; %s with %s reg %u"),
> - cfi_esc_p ? ".cfi_escape DW_CFA_val_offset" : ".cfi_val_offset",
> - sframe_register_name (cfi_insn->u.ri.reg), cfi_insn->u.ri.reg);
> + sframe_as_warn (_("no SFrame FDE emitted; %s with %s reg %u"),
> + cfi_esc_p ? ".cfi_escape DW_CFA_val_offset" : ".cfi_val_offset",
> + sframe_register_name (cfi_insn->u.ri.reg), cfi_insn->u.ri.reg);
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
>
> @@ -1217,8 +1217,8 @@ sframe_xlate_do_register (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
> /* Ignore SP reg, as it can be recovered from the CFA tracking info. */
> )
> {
> - as_warn (_("no SFrame FDE emitted; %s register %u in .cfi_register"),
> - sframe_register_name (cfi_insn->u.rr.reg1), cfi_insn->u.rr.reg1);
> + sframe_as_warn (_("no SFrame FDE emitted; %s register %u in .cfi_register"),
> + sframe_register_name (cfi_insn->u.rr.reg1), cfi_insn->u.rr.reg1);
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
>
> @@ -1239,8 +1239,8 @@ sframe_xlate_do_remember_state (struct sframe_xlate_ctx *xlate_ctx)
> info for the function involved. */
> if (!last_fre)
> {
> - as_warn (_("no SFrame FDE emitted; "
> - ".cfi_remember_state without prior SFrame FRE state"));
> + sframe_as_warn (_("no SFrame FDE emitted; "
> + ".cfi_remember_state without prior SFrame FRE state"));
> return SFRAME_XLATE_ERR_INVAL;
> }
>
> @@ -1340,7 +1340,7 @@ static int
> sframe_xlate_do_aarch64_negate_ra_state_with_pc (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
> struct cfi_insn_data *cfi_insn ATTRIBUTE_UNUSED)
> {
> - as_warn (_("no SFrame FDE emitted; .cfi_negate_ra_state_with_pc"));
> + sframe_as_warn (_("no SFrame FDE emitted; .cfi_negate_ra_state_with_pc"));
> /* The used signing method should be encoded inside the FDE in SFrame v3.
> For now, PAuth_LR extension is not supported with SFrame. */
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> @@ -1367,7 +1367,8 @@ sframe_xlate_do_gnu_window_save (struct sframe_xlate_ctx *xlate_ctx,
> || abi_arch == SFRAME_ABI_AARCH64_ENDIAN_LITTLE)
> return sframe_xlate_do_aarch64_negate_ra_state (xlate_ctx, cfi_insn);
>
> - as_warn (_("no SFrame FDE emitted; .cfi_window_save"));
> + sframe_as_warn (_("no SFrame FDE emitted; .cfi_window_save"));
> +
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
>
> @@ -1425,9 +1426,9 @@ sframe_xlate_do_escape_expr (const struct sframe_xlate_ctx *xlate_ctx,
> || (sframe_ra_tracking_p () && reg == SFRAME_CFA_RA_REG)
> || reg == xlate_ctx->cur_fre->cfa_base_reg)
> {
> - as_warn (_("no SFrame FDE emitted; "
> - ".cfi_escape DW_CFA_expression with %s reg %u"),
> - sframe_register_name (reg), reg);
> + sframe_as_warn (_("no SFrame FDE emitted; "
> + ".cfi_escape DW_CFA_expression with %s reg %u"),
> + sframe_register_name (reg), reg);
> err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
> /* else safe to skip, so continue to return SFRAME_XLATE_OK. */
> @@ -1586,8 +1587,8 @@ sframe_xlate_do_cfi_escape (const struct sframe_xlate_ctx *xlate_ctx,
> OS-specific CFI opcodes), skip inspecting the DWARF expression.
> This may impact the asynchronicity due to loss of coverage.
> Continue to warn the user and bail out. */
> - as_warn (_("no SFrame FDE emitted; .cfi_escape with op (%#lx)"),
> - (unsigned long)firstop);
> + sframe_as_warn (_("no SFrame FDE emitted; .cfi_escape with op (%#lx)"),
> + (unsigned long)firstop);
> err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
>
> @@ -1611,8 +1612,8 @@ sframe_xlate_do_cfi_undefined (const struct sframe_xlate_ctx *xlate_ctx ATTRIBUT
> || cfi_insn->u.r == SFRAME_CFA_RA_REG
> || cfi_insn->u.r == SFRAME_CFA_SP_REG)
> {
> - as_warn (_("no SFrame FDE emitted; %s reg %u in .cfi_undefined"),
> - sframe_register_name (cfi_insn->u.r), cfi_insn->u.r);
> + sframe_as_warn (_("no SFrame FDE emitted; %s reg %u in .cfi_undefined"),
> + sframe_register_name (cfi_insn->u.r), cfi_insn->u.r);
> return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
> }
>
> @@ -1789,8 +1790,9 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
>
> if (!cfi_name)
> cfi_name = _("(unknown)");
> - as_warn (_("no SFrame FDE emitted; CFI insn %s (%#x)"),
> - cfi_name, op);
> +
> + sframe_as_warn (_("no SFrame FDE emitted; CFI insn %s (%#x)"),
> + cfi_name, op);
> err = SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
> }
> @@ -1813,8 +1815,8 @@ 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 (_("no SFrame FDE emitted; non-default RA register %u"),
> - xlate_ctx->dw_fde->return_column);
> + sframe_as_warn (_("no SFrame FDE emitted; non-default RA register %u"),
> + xlate_ctx->dw_fde->return_column);
> return SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
>
> @@ -1858,7 +1860,7 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
> if (fre->ra_loc != SFRAME_FRE_ELEM_LOC_STACK
> && fre->bp_loc == SFRAME_FRE_ELEM_LOC_STACK)
> {
> - as_warn (_("no SFrame FDE emitted; FP without RA on stack"));
> + sframe_as_warn (_("no SFrame FDE emitted; FP without RA on stack"));
> return SFRAME_XLATE_ERR_NOTREPRESENTED;
> }
> }
> diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
> index 8ad521b5cbe..7e69aae9ed0 100644
> --- a/gas/gen-sframe.h
> +++ b/gas/gen-sframe.h
> @@ -21,6 +21,14 @@
> #ifndef GENSFRAME_H
> #define GENSFRAME_H
>
> +/* Warnings shouldn't be emitted for the default-enabled case, only when
> + --gsframe is explicitly passed by the user. */
> +#define sframe_as_warn(format, ...) \
> + do { \
> + if (flag_gen_sframe == GEN_SFRAME_ENABLED) \
> + as_warn (format, ##__VA_ARGS__); \
> + } while (0)
> +
> /* Errors shouldn't be emitted either if SFrames are default-enabled, as
> we interpret default-enabled as "opportunistic SFrames". Users don't
> want to be bothered by something preventing emission of SFrames in
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