[binutils-gdb] gas: ld: libsframe: Support for SFrame FDEs without any FREs

[Jens Remus]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=c47ec3b44a6457a950847fd984074a1c02f7fc54

commit c47ec3b44a6457a950847fd984074a1c02f7fc54
Author: Jens Remus <jremus@linux.ibm.com>
Date:   Wed Oct 15 17:45:48 2025 +0200

    gas: ld: libsframe: Support for SFrame FDEs without any FREs
    
    Allow SFrame sections without any FREs, that can occur if they solely
    contain FDEs without any FREs.  For FDEs without and FREs set the
    offset to the first FRE to zero.
    
    libsframe/
            * sframe.c (sframe_encoder_write_sframe): Allow SFrame sections
            without any FREs.  For FDEs without any FREs set the offset to
            the first FRE to zero.
    
    gas/
            * gen-sframe.c (output_sframe_funcdesc): For FDEs without any
            FREs set the offset to the first FRE to zero.
    
    Signed-off-by: Jens Remus <jremus@linux.ibm.com>

Diff:
---
 gas/gen-sframe.c   | 18 ++++++++++++------
 libsframe/sframe.c |  9 ++++++++-
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index b9db87f6c64..8643ee8731e 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -652,12 +652,18 @@ output_sframe_funcdesc (symbolS *start_of_fre_section,
 				  sfde_func_size));
 
   /* Offset to the first frame row entry.  */
-  exp.X_op = O_subtract;
-  exp.X_add_symbol = fre_symbol; /* Minuend.  */
-  exp.X_op_symbol = start_of_fre_section; /* Subtrahend.  */
-  exp.X_add_number = 0;
-  emit_expr (&exp, sizeof_member (sframe_func_desc_entry,
-				  sfde_func_start_fre_off));
+  if (sframe_fde->num_fres == 0)
+    /* For FDEs without any FREs, set sfde_func_start_fre_off to zero.  */
+    out_four (0);
+  else
+    {
+      exp.X_op = O_subtract;
+      exp.X_add_symbol = fre_symbol; /* Minuend.  */
+      exp.X_op_symbol = start_of_fre_section; /* Subtrahend.  */
+      exp.X_add_number = 0;
+      emit_expr (&exp, sizeof_member (sframe_func_desc_entry,
+				      sfde_func_start_fre_off));
+    }
 
   /* Number of FREs.  */
   out_four (sframe_fde->num_fres);
diff --git a/libsframe/sframe.c b/libsframe/sframe.c
index 85500791f8a..b70b0e880c9 100644
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -1882,7 +1882,7 @@ sframe_encoder_write_sframe (sframe_encoder_ctx *encoder)
      - buffers must be malloc'd by the caller.  */
   if ((contents == NULL) || (buf_size < hdr_size))
     return sframe_set_errno (&err, SFRAME_ERR_BUF_INVAL);
-  if (fr_info == NULL)
+  if (ehp->sfh_num_fres > 0 && fr_info == NULL)
     return sframe_set_errno (&err, SFRAME_ERR_FRE_INVAL);
 
   /* Write out the FRE table first.
@@ -1905,6 +1905,13 @@ sframe_encoder_write_sframe (sframe_encoder_ctx *encoder)
       fre_type = sframe_get_fre_type (fdep);
       num_fres = fdep->sfde_func_num_fres;
 
+      /* For FDEs without any FREs, set sfde_func_start_fre_off to zero.  */
+      if (num_fres == 0)
+	fdep->sfde_func_start_fre_off = 0;
+
+      if (num_fres > 0 && fr_info == NULL)
+	return sframe_set_errno (&err, SFRAME_ERR_FRE_INVAL);
+
       for (j = 0; j < num_fres; j++)
 	{
 	  fre_index = global + j;