[PATCH v4 09/15] gas: User readable warnings if SFrame FDE is not generated
Jens Remus
jremus@linux.ibm.com
Mon Jun 24 14:23:28 GMT 2024
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; CFI insn <name> (0x<hexval>)
Whenever possible print meaningful warning messages, when the assembler
skips generation of SFrame FDE:
- skipping SFrame FDE; non-SP/FP register <regno> in .cfi_def_cfa
- skipping SFrame FDE; non-SP/FP register <regno> in
.cfi_def_cfa_register
- skipping SFrame FDE; .cfi_def_cfa_offset without CFA base register
in effect
- skipping SFrame FDE; {FP|RA} register <regno> in .cfi_val_offset
- skipping SFrame FDE; {SP|FP|RA} register <regno> in in .cfi_register
- skipping SFrame FDE; .cfi_remember_state without prior SFrame FRE
state
- 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 v3 -> v4:
- Use terse warning message texts as suggested by Indu.
- Fix bad indentation reported by GCC's check_GNU_style.py.
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 | 92 ++++++++++++++-----
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, 72 insertions(+), 28 deletions(-)
diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index 4809619f4636..3d9824a7a080 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -869,7 +869,7 @@ 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. */
@@ -924,6 +924,23 @@ 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. */
@@ -992,7 +1009,11 @@ 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; non-SP/FP register %u in .cfi_def_cfa"),
+ 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;
@@ -1017,7 +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; "
+ "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.ri.reg);
sframe_fre_set_cfa_offset (cur_fre, last_fre->cfa_offset);
cur_fre->merge_candidate = false;
@@ -1048,7 +1074,13 @@ sframe_xlate_do_def_cfa_offset (struct sframe_xlate_ctx *xlate_ctx,
cur_fre->merge_candidate = false;
}
else
- return SFRAME_XLATE_ERR_NOTREPRESENTED;
+ {
+ /* 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 (_("skipping SFrame FDE; "
+ ".cfi_def_cfa_offset without CFA base register in effect"));
+ return SFRAME_XLATE_ERR_NOTREPRESENTED;
+ }
return SFRAME_XLATE_OK;
}
@@ -1098,13 +1130,16 @@ 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; %s register %u in .cfi_val_offset"),
+ sframe_register_name (cfi_insn->u.r), cfi_insn->u.r);
+ return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented. */
+ }
/* Safe to skip. */
return SFRAME_XLATE_OK;
@@ -1126,7 +1161,11 @@ 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; %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. */
+ }
/* Safe to skip. */
return SFRAME_XLATE_OK;
@@ -1144,7 +1183,11 @@ 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; "
+ ".cfi_remember_state without prior SFrame FRE state"));
+ return SFRAME_XLATE_ERR_INVAL;
+ }
if (!xlate_ctx->remember_fre)
xlate_ctx->remember_fre = sframe_row_entry_new ();
@@ -1332,21 +1375,19 @@ 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; CFI insn %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; CFI insn %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;
}
@@ -1363,7 +1404,8 @@ 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; non-default RA 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 dbb48949c713..6e99dd57af94 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; CFI insn DW_CFA_remember_state \(0xa\)
+#warning: skipping SFrame FDE; \.cfi_remember_state without prior 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 7b2ce3e8c796..77c303eec8fb 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; CFI insn DW_CFA_def_cfa_offset \(0xe\)
+#warning: skipping SFrame FDE; \.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..4ec5b44dd51f 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; non-default RA register 0
#objdump: --sframe=.sframe
#name: SFrame supports only default return column
#...
--
2.40.1
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