[PATCH v3 07/15] gas: Warn if SFrame FDE is skipped due to non-default return column

[Jens Remus]

Print a warning message if SFrame FDE is skipped due to a non-default
DWARF return column (i.e. return address (RA) register number). This
may be caused by the use of CFI directive .cfi_return_column with a
non-default return address (RA) register number in the processed
assembler source code.

  Warning: skipping SFrame FDE due to non-default DWARF return column

gas/
	* gen-sframe.c: Warn if SFrame FDE is skipped due to non-default
	DWARF return column.

gas/testsuite/
	* gas/cfi-sframe/common-empty-3.d: Update test case to expect
	for new warning message when SFrame FDE is skipped due to
	a non-default DWARF return column.

Reviewed-by: Andreas Krebbel <krebbel@linux.ibm.com>
Reviewed-by: Indu Bhagat <indu.bhagat@oracle.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
---

Notes (jremus):
    Changes v2 -> v3:
    - Enhance comment in code as suggested by Indu.
    - Corrected formatting of ChangeLog in commit message.
    
    Without this patch the assembler would generate incomplete SFrame
    information without warning for the s390-specific SFrame error test
    case 4, that gets introduced by patch "s390: Initial support to
    generate .sframe from CFI directives in assembler".

 gas/gen-sframe.c                              | 10 +++++++---
 gas/testsuite/gas/cfi-sframe/common-empty-3.d |  1 +
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index 1269b2b77c54..fe8b24906c1b 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -1343,9 +1343,12 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
 
   xlate_ctx->dw_fde = dw_fde;
 
-  /* If the return column is not RIP, SFrame format cannot represent it.  */
+  /* SFrame format cannot represent a non-default DWARF return column reg.  */
   if (xlate_ctx->dw_fde->return_column != DWARF2_DEFAULT_RETURN_COLUMN)
-    return SFRAME_XLATE_ERR_NOTREPRESENTED;
+    {
+      as_warn (_("skipping SFrame FDE due to non-default DWARF return column"));
+      return SFRAME_XLATE_ERR_NOTREPRESENTED;
+    }
 
   /* Iterate over the CFIs and create SFrame FREs.  */
   for (cfi_insn = dw_fde->data; cfi_insn; cfi_insn = cfi_insn->next)
@@ -1355,7 +1358,8 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
       if (err != SFRAME_XLATE_OK)
 	{
 	  /* Skip generating SFrame stack trace info for the function if any
-	     offending CFI is encountered by sframe_do_cfi_insn ().  */
+	     offending CFI is encountered by sframe_do_cfi_insn ().  Warning
+	     message already printed by sframe_do_cfi_insn ().  */
 	  return err; /* Return the error code.  */
 	}
     }
diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-3.d b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
index 5914c620760d..d17521dd88ea 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-3.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-3.d
@@ -1,4 +1,5 @@
 #as: --gsframe
+#warning: skipping SFrame FDE due to non-default DWARF return column
 #objdump: --sframe=.sframe
 #name: SFrame supports only default return column
 #...
-- 
2.40.1