diff mbox series

[8/9] gas: User readable warnings if SFrame FDE is not generated

Message ID 20240222160123.2554459-9-jremus@linux.ibm.com
State Unresolved
Headers
Series s390: Initial support to generate SFrame info from CFI directives in assembler |

Checks

Context Check Description
snail/binutils-gdb-check warning Git am fail log

Commit Message

Jens Remus Feb. 22, 2024, 4:01 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 specifying CFA base register
  other than SP or FP (<regno> instead of <SP-regno> or <FP-regno>)
- 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>)
- 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>)
- 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
- 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>)

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 mbox series

Patch

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
 #...