Re: gas -Werror compilation break [Re: [patch ld bfd gas]: Handle linkonce for cfi generated debug_frame and eh_frame data]

[Dave Korn <dave dot korn dot cygwin at gmail dot com>]

On 27/04/2011 21:34, Jan Kratochvil wrote:
> Hi Kai,
> 
> On Tue, 26 Apr 2011 17:30:08 +0200, Nick Clifton wrote:
>>>>>  ChangeLog gas/
>>>>>  2011-04-18  Kai Tietz
>>>>>
>>>>>         * dw2gencfi.c (dwcfi_seg_list): New struct.
>>>>>         (dwcfi_hash): New static hash variable.
>>>>>         (get_debugseg_name): New.
>>>>>         (alloc_debugseg_item): New.
>>>>>         (make_debug_seg): New.
>>>>>         (dwcfi_hash_insert): New.
>>>>>         (dwcfi_hash_find): New.
>>>>>         (dwcfi_hash_find_or_make): New.
>>>>>         (cfi_insn_data): New member cur_seg.
>>>>>         (cie_entry): Likewise.
>>>>>         (fde_entry): New cseg and handled members.
>>>>>         (alloc_fde_entry): Initialize cseg member.
>>>>>         (alloc_cfi_insn_data): Initialize cur_seg member.
>>>>>         (dot_cfi_sections): Compare for beginning of
>>>>>         section names via strncmp.
>>>>>         (get_cfi_seg): New.
>>>>>         (cfi_finish): Treat link-once sections.
>>>>>         (is_now_linkonce_segment): New local helper.
>>>>>         (output_cie): Ignore cie entries not member of current
>>>>>         segment.
>>>>>         (output_fde): Likewise.
>>>>>         (select_cie_for_fde): Likewise.
>>>>>         (cfi_change_reg_numbers): Add new argument for current segment
>>>>>         and ignore insn elements, if not part of current segment.
>>>>>         * ehopt.c (get_cie_info): Use strncmp for
>>>>>         section name matching.
>>>>>         (heck_eh_frame): Likewise.
> 
> dw2gencfi.c:1870:8: error: variable ‘cfi_seg’ set but not used [-Werror=unused-but-set-variable]
> gcc-4.6.0-5.fc15.x86_64
> 
> Could you please provide a fix?

  This fixes the breakage, but doesn't address the issue that it looks to me
like there's an omitted call to md_fix_up_eh_frame() after the second
invocation of get_cfi_seg().

gas/ChangeLog:

	* dw2gencfi.c (dwcfi_hash): Wrap in #ifdef md_fix_up_eh_frame.
	(get_debugseg_name): Likewise.
	(alloc_debugseg_item): Likewise.
	(make_debug_seg): Likewise.
	(dwcfi_hash_insert): Likewise.
	(dwcfi_hash_find): Likewise.
	(dwcfi_hash_find_or_make): Likewise.
	(get_cfi_seg): Likewise.
	(cfi_finish): Wrap references to cfi_seg and calls to get_cfi_seg()
	in #ifdef md_fix_up_eh_frame likewise.

  Verified that it fixes the build on i686-pc-cygwin and
x86_64-unknown-linux-gnu, OK to install?

    cheers,
      DaveK

Index: gas/dw2gencfi.c
===================================================================
RCS file: /cvs/src/src/gas/dw2gencfi.c,v
retrieving revision 1.52
diff -p -u -r1.52 dw2gencfi.c
--- gas/dw2gencfi.c	26 Apr 2011 15:28:07 -0000	1.52
+++ gas/dw2gencfi.c	5 May 2011 00:18:58 -0000
@@ -86,6 +86,7 @@ struct dwcfi_seg_list
 
 #define FRAME_NAME ".eh_frame"
 
+#ifdef md_fix_up_eh_frame
 static struct hash_control *dwcfi_hash;
 
 /* Build based on segment the derived .debug_...
@@ -137,6 +138,7 @@ alloc_debugseg_item (segT seg, int subse
   r->seg_name = name;
   return r;
 }
+#endif
 
 static segT
 is_now_linkonce_segment (void)
@@ -151,6 +153,7 @@ is_now_linkonce_segment (void)
   return NULL;
 }
 
+#ifdef md_fix_up_eh_frame
 /* Generate debug... segment with same linkonce properties
    of based segment.  */
 
@@ -227,6 +230,7 @@ dwcfi_hash_find_or_make (segT cseg, cons
 
   return item;
 }
+#endif
 
 /* ??? Share this with dwarf2cfg.c.  */
 #ifndef TC_DWARF2_EMIT_OFFSET
@@ -1851,6 +1855,7 @@ cfi_change_reg_numbers (struct cfi_insn_
 #define cfi_change_reg_numbers(insn, cseg) do { } while (0)
 #endif
 
+#ifdef md_fix_up_eh_frame
 static segT
 get_cfi_seg (segT cseg, const char *base, flagword flags, int align)
 {
@@ -1862,12 +1867,16 @@ get_cfi_seg (segT cseg, const char *base
   record_alignment (l->seg, align);
   return l->seg;
 }
+#endif
 
 void
 cfi_finish (void)
 {
   struct cie_entry *cie, *cie_next;
-  segT cfi_seg, ccseg;
+#ifdef md_fix_up_eh_frame
+  segT cfi_seg;
+#endif
+  segT ccseg;
   struct fde_entry *fde;
   struct cfi_insn_data *first;
   int save_flag_traditional_format, seek_next_seg;
@@ -1884,7 +1893,9 @@ cfi_finish (void)
       do
         {
 	  ccseg = NULL;
+#ifdef md_fix_up_eh_frame
 	  cfi_seg = NULL;
+#endif
 	  seek_next_seg = 0;
 	  for (cie = cie_root; cie; cie = cie_next)
 	    {
@@ -1905,12 +1916,12 @@ cfi_finish (void)
 	      if (!seek_next_seg)
 	        {
 		  ccseg = fde->cseg;
+#ifdef md_fix_up_eh_frame
 		  /* Open .eh_frame section.  */
 		  cfi_seg = get_cfi_seg (ccseg, ".eh_frame",
 					 SEC_ALLOC | SEC_LOAD | SEC_DATA
 					 | DWARF2_EH_FRAME_READ_ONLY,
 					 EH_FRAME_ALIGNMENT);
-#ifdef md_fix_up_eh_frame
 		  md_fix_up_eh_frame (cfi_seg);
 #endif
 		  seek_next_seg = 1;
@@ -1943,7 +1954,9 @@ cfi_finish (void)
       do
         {
 	  ccseg = NULL;
+#ifdef md_fix_up_eh_frame
 	  cfi_seg = NULL;
+#endif
 	  seek_next_seg = 0;
 	  for (cie = cie_root; cie; cie = cie_next)
 	    {
@@ -1964,10 +1977,12 @@ cfi_finish (void)
 	      if (!seek_next_seg)
 	        {
 		  ccseg = fde->cseg;
+#ifdef md_fix_up_eh_frame
 		  /* Open .debug_frame section.  */
 		  cfi_seg = get_cfi_seg (ccseg, ".debug_frame",
 					 SEC_READONLY | SEC_DEBUGGING,
 					 alignment);
+#endif
 		  seek_next_seg = 1;
 		}
 	      fde->handled = 1;