[Bug ld/9841] avr-ld crashes when -relax is used with ATMega8535 target

[pwilson at scopuli dot com]

------- Additional Comments From pwilson at scopuli dot com  2009-02-14 18:41 
-------
I looked at the context of the call to elf32_avr_relax_delete_bytes()
and how symtab_hdr->contents is assigned.  I then compared the AVR to
other architectures calling their elf32_*_relax_delete_bytes()
function, and it appears to me that the AVR relax implementation is
based upon the h8300 relax implementation.  In fact, I searched for
h8300 in elf32-avr.c and found a reference to cut-n-pasting code from
the h8300 port.

So I looked at the calls to elf32_h8_relax_delete_bytes(), and
before every call there are these lines of code:

 elf_section_data (sec)->relocs = internal_relocs;
 elf_section_data (sec)->this_hdr.contents = contents;
 symtab_hdr->contents = (unsigned char *) isymbuf;

Those lines of code also appear before the only other call to
elf32_avr_relax_delete_bytes() within elf32-avr.c.  These lines are
missing before the call to elf32_avr_relax_delete_bytes() where the
crash happens, and I believe that is the source of the problem.

I placed those assignments within the
 if (deleting_ret_is_safe)
block before the call to elf32_avr_relax_delete_bytes() and that fixes
the problem.

Here is a proposed patch

 diff -Nur binutils-2.19-orig/bfd/elf32-avr.c binutils-2.19/bfd/elf32-avr.c
--- binutils-2.19-orig/bfd/elf32-avr.c  2009-02-14 12:54:24.000000000 -0500
+++ binutils-2.19/bfd/elf32-avr.c       2009-02-14 13:06:49.000000000 -0500
@@ -2252,6 +2252,12 @@
                                        "at address 0x%x deleted.\n",
                                        (int) dot + insn_size);
 
+                             /* Note that we've changed the relocs,
+                                section contents, etc.  */
+                             elf_section_data (sec)->relocs = internal_relocs;
+                             elf_section_data (sec)->this_hdr.contents = 
contents;
+                             symtab_hdr->contents = (unsigned char *) isymbuf;
+
                              /* Delete two bytes of data.  */
                              if (!elf32_avr_relax_delete_bytes (abfd, sec,
                                         irel->r_offset + insn_size, 2))


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=9841

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