[binutils-gdb] gas: sframe: warn when skipping SFrame FDE generation

[Indu Bhagat]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6bf40ece270c42b0e5f90459a7dde851e3e7485d

commit 6bf40ece270c42b0e5f90459a7dde851e3e7485d
Author: Indu Bhagat <indu.bhagat@oracle.com>
Date:   Fri Jan 12 00:22:12 2024 -0800

    gas: sframe: warn when skipping SFrame FDE generation
    
    Fix PR gas/31213.
    
    gas/
            PR gas/31213
            * gen-sframe.c (sframe_do_cfi_insn): Add new warning.
    
    gas/testsuite/
            * gas/cfi-sframe/common-empty-1.d: Test the new warning as well.
            * gas/cfi-sframe/common-empty-2.d: Likewise.

Diff:
---
 gas/gen-sframe.c                              | 34 +++++++++++++++++----------
 gas/testsuite/gas/cfi-sframe/common-empty-1.d |  1 +
 gas/testsuite/gas/cfi-sframe/common-empty-2.d |  1 +
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index 3c212f3a882..75781fc8ccb 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -1247,25 +1247,33 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
     case DW_CFA_GNU_window_save:
       err = sframe_xlate_do_gnu_window_save (xlate_ctx, cfi_insn);
       break;
+    /* Other CFI opcodes are not processed at this time.
+       These do not impact the coverage of the basic stack tracing
+       information as conveyed in the SFrame format.
+	- DW_CFA_register,
+	- etc.  */
+    case DW_CFA_register:
+      if (cfi_insn->u.rr.reg1 == SFRAME_CFA_SP_REG
+#ifdef SFRAME_FRE_RA_TRACKING
+	  || cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG
+#endif
+	  || cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG)
+	err = SFRAME_XLATE_ERR_NOTREPRESENTED;
+      break;
     case DW_CFA_undefined:
     case DW_CFA_same_value:
       break;
     default:
-      {
-	/* Other CFI opcodes are not processed at this time.
-	   These do not impact the coverage of the basic stack tracing
-	   information as conveyed in the SFrame format.
-	    - DW_CFA_register,
-	    - ...
-
-	   Following skipped operations do, however, impact the asynchronicity:
-	     - CFI_escape  */
-
-	err = SFRAME_XLATE_ERR_NOTREPRESENTED;
-	// printf (_("SFrame Unsupported or unknown Dwarf CFI number: %#x\n"), op);
-      }
+      /* 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)
+    as_warn (_("skipping SFrame FDE due to DWARF CFI op %#x"), op);
+
   return err;
 }
 
diff --git a/gas/testsuite/gas/cfi-sframe/common-empty-1.d b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
index 141922517f0..b133b15b051 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-1.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-1.d
@@ -1,4 +1,5 @@
 #as: --gsframe
+#warning: skipping SFrame FDE due to DWARF CFI op 0xa
 #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 ab8de0b8afa..c5bc8594f1b 100644
--- a/gas/testsuite/gas/cfi-sframe/common-empty-2.d
+++ b/gas/testsuite/gas/cfi-sframe/common-empty-2.d
@@ -1,4 +1,5 @@
 #as: --gsframe
+#warning: skipping SFrame FDE due to DWARF CFI op 0xe
 #objdump: --sframe=.sframe
 #name: SFrame supports only FP/SP based CFA
 #...