[binutils-gdb] Fix a bug displaying the interpretation of a CFA block that just contains DW_CFA_NOP instructions.

[Nick Clifton <nickc at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5b6312fd20ef39f1531e37e7d2601c54d5658119

commit 5b6312fd20ef39f1531e37e7d2601c54d5658119
Author: Nick Clifton <nickc@redhat.com>
Date:   Thu Jun 2 11:34:49 2016 +0100

    Fix a bug displaying the interpretation of a CFA block that just contains DW_CFA_NOP instructions.
    
    	* dwarf.c (display_debug_frames): Do not display any
    	interpretation if the block consists solely of DW__CFA_NOPs.

Diff:
---
 binutils/ChangeLog |  5 +++++
 binutils/dwarf.c   | 10 +++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index ee27763..9dfaf2b 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-02  Nick Clifton  <nickc@redhat.com>
+
+	* dwarf.c (display_debug_frames): Do not display any
+	interpretation if the block consists solely of DW__CFA_NOPs.
+
 2016-05-31  Alan Modra  <amodra@gmail.com>
 
 	* objcopy.c: Formatting, whitespace throughout.
diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 770fa6b..282e069 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -5780,6 +5780,7 @@ display_debug_frames (struct dwarf_section *section,
       unsigned int encoded_ptr_size = saved_eh_addr_size;
       unsigned int offset_size;
       unsigned int initial_length_size;
+      bfd_boolean all_nops;
 
       saved_start = start;
 
@@ -6213,6 +6214,8 @@ display_debug_frames (struct dwarf_section *section,
 	  start = tmp;
 	}
 
+      all_nops = TRUE;
+
       /* Now we know what registers are used, make a second pass over
 	 the chunk, this time actually printing out the info.  */
 
@@ -6231,6 +6234,10 @@ display_debug_frames (struct dwarf_section *section,
 	  if (op & 0xc0)
 	    op &= 0xc0;
 
+	  /* Make a note if something other than DW_CFA_nop happens.  */
+	  if (op != DW_CFA_nop)
+	    all_nops = FALSE;
+
 	  /* Warning: if you add any more cases to this switch, be
 	     sure to add them to the corresponding switch above.  */
 	  switch (op)
@@ -6661,7 +6668,8 @@ display_debug_frames (struct dwarf_section *section,
 	    }
 	}
 
-      if (do_debug_frames_interp)
+      /* Interpret the CFA - as long as it is not completely full of NOPs.  */
+      if (do_debug_frames_interp && ! all_nops)
 	frame_display_row (fc, &need_col_headers, &max_regs);
 
       start = block_end;