[RFA] skip fde augmentation

[RFA] skip fde augmentation

[Richard Henderson]

Found by inspection.

I assume that the bulk of the dwarf2 testing has been done
on C code.  C++ code that handles exceptions would wind up
executing bogus CFA opcodes.

Ok?


r~



	* dwarf2-frame.c (struct dwarf2_cie): Add saw_z_augmentation.
	(decode_frame_entry): Set it.  Skip FDE augmentation.

--- dwarf2-frame.c.orig	2003-05-31 22:23:54.000000000 -0700
+++ dwarf2-frame.c	2003-05-31 22:30:21.000000000 -0700
@@ -65,6 +65,9 @@ struct dwarf2_cie
   /* Encoding of addresses.  */
   unsigned char encoding;
 
+  /* True if a 'z' augmentation existed.  */
+  unsigned char saw_z_augmentation;
+
   struct dwarf2_cie *next;
 };
 
@@ -1111,7 +1114,8 @@ decode_frame_entry (struct comp_unit *un
       cie->return_address_register = read_1_byte (unit->abfd, buf);
       buf += 1;
 
-      if (*augmentation == 'z')
+      cie->saw_z_augmentation = (*augmentation == 'z');
+      if (cie->saw_z_augmentation)
 	{
 	  ULONGEST length;
 
@@ -1200,6 +1204,18 @@ decode_frame_entry (struct comp_unit *un
 	read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read);
       buf += bytes_read;
 
+      /* A 'z' augmentation in the CIE implies the presence of an
+	 augmentation field in the FDE as well.  The only thing known
+	 to be in here at present is the LSDA entry for EH.  So we
+	 can skip the whole thing.  */
+      if (fde->cie->saw_z_augmentation)
+	{
+	  ULONGEST length;
+
+	  length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
+	  buf += bytes_read + length;
+	}
+
       fde->instructions = buf;
       fde->end = end;
 

Re: [RFA] skip fde augmentation

[Mark Kettenis]

Richard Henderson <rth@twiddle.net> writes:

> Found by inspection.
> 
> I assume that the bulk of the dwarf2 testing has been done
> on C code.  C++ code that handles exceptions would wind up
> executing bogus CFA opcodes.
> 
> Ok?
> 
> r~
> 
> 	* dwarf2-frame.c (struct dwarf2_cie): Add saw_z_augmentation.
> 	(decode_frame_entry): Set it.  Skip FDE augmentation.

I must have missed this when looking at GCC's unwinder.  Approved.

Mark