[Bug bootstrap/33070] New: Bootstrap comparison failure between stage2/3 but no objdump differences

[Bug bootstrap/33070] New: Bootstrap comparison failure between stage2/3 but no objdump differences

[Axel dot Thimm at ATrpms dot net]

While trying to build gcc 3.4.3 on a RHEL5/i386 system in a chroot we see

> Comparing stage2 and stage3 of the compiler
> gmake[1]: Entering directory `/opt/build/gcc-3.4.3-objdir3/gcc'
> [...]
> Bootstrap comparison failure!
> ./alloc-pool.o differs
> ./bb-reorder.o differs
> ./bt-load.o differs
> [...]

The list of object files can differ, and the differences are not visible with
disassembling with objdump (see below). It looks like the differences are from
the padding space between the aligned sections. What could be wrong?

If the build is done outside the chroot then the comparison succeeds. We have
already tried to map everything outside/inside the chroot (including /proc,
/dev etc) but sysfs and binfmt_misc. Does the gcc stage 2/3 build make any use
of these?

Thanks!

[root@franky ~]# file1=/opt/build/gcc-3.4.3-objdir3/gcc/stage2/alloc-pool.o;
file2=/opt/build/gcc-3.4.3-objdir3/gcc/alloc-pool.o
[root@franky ~]# cmp -l $file1 $file2
2714  75 262
2715 312  57
2716  10  12
[root@franky ~]# objdump -Dxzs --prefix-addresses $file1 > /tmp/c-1
[root@franky ~]# objdump -Dxzs --prefix-addresses $file2 > /tmp/c-2
[root@franky ~]# diff -ud /tmp/c-1 /tmp/c-2
--- /tmp/c-1    2007-08-14 12:31:37.000000000 -0500
+++ /tmp/c-2    2007-08-14 12:31:42.000000000 -0500
@@ -1,6 +1,6 @@

-/opt/build/gcc-3.4.3-objdir3/gcc/stage2/alloc-pool.o:     file format
elf32-i386
-/opt/build/gcc-3.4.3-objdir3/gcc/stage2/alloc-pool.o
+/opt/build/gcc-3.4.3-objdir3/gcc/alloc-pool.o:     file format elf32-i386
+/opt/build/gcc-3.4.3-objdir3/gcc/alloc-pool.o
 architecture: i386, flags 0x00000011:
 HAS_RELOC, HAS_SYMS
 start address 0x00000000


-- 
           Summary: Bootstrap comparison failure between stage2/3 but no
                    objdump differences
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Axel dot Thimm at ATrpms dot net
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

[Bug bootstrap/33070] Bootstrap comparison failure between stage2/3 but no objdump differences

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-08-20 06:45 -------
Considering how old 3.4.3 is, I doubt we can do anything to help you here
except to suggest to try 4.2.1, the latest release.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

[Bug bootstrap/33070] Bootstrap comparison failure between stage2/3 but no objdump differences

[Axel dot Thimm at ATrpms dot net]

------- Comment #2 from Axel dot Thimm at ATrpms dot net  2007-08-20 07:36 -------
(In reply to comment #1)
> Considering how old 3.4.3 is, I doubt we can do anything to help you here
> except to suggest to try 4.2.1, the latest release.

We would need to stay at 3.4.x. If we can reproduce this for the latest 3.4.x
release (3.4.6) would there be interest in fixing it? Thanks!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

[Bug bootstrap/33070] Bootstrap comparison failure between stage2/3 but no objdump differences

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2007-08-20 07:40 -------
(In reply to comment #2)
> We would need to stay at 3.4.x. If we can reproduce this for the latest 3.4.x
> release (3.4.6) would there be interest in fixing it? Thanks!

None as 3.4.x is no longer supported.  Why do you need to stay with 3.4.x?  The
C++/libstdc++ ABI has not changed between 3.4.0 and 4.2.1 at all.

Also this works for me when I last bootstrapped a 3.4.x based compiler around 2
years ago


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

[Bug bootstrap/33070] Bootstrap comparison failure between stage2/3 but no objdump differences

[Axel dot Thimm at ATrpms dot net]

------- Comment #4 from Axel dot Thimm at ATrpms dot net  2007-08-20 18:05 -------
The same thing happens with 4.2.1, only that there are additional warnings
before:

Comparing stages 2 and 3
warning: ./libgcc/_fixunssfdi.o differs
warning: ./libgcc/_udivmoddi4_s.o differs
[...]
warning: ./libgcc/_udivdi3_s.o differs
warning: ./libgcc/_fixunsdfdi.o differs
Bootstrap comparison failure!
./alloc-pool.o differs
./tree-into-ssa.o differs
./local-alloc.o differs
./cppdefault.o differs
[...]

Comparing the object files shows differences like

for alloc-pool.o

3098 370   0
3099 317   0
3100 267   0
3200 267   0

or for tree-into-ssa.o

 31349 360   0
 31350 303   0
 31351 341   0
 31352 267   0
 31353  14  23
 31357  40 150
 31358   0 324
 31359   0 244
 31360   0 267
 31414   0 132
 31415   0 244
 31416   0 267

and the objdump disassembly is the same (but the files' paths).


-- 

Axel dot Thimm at ATrpms dot net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|3.4.3                       |4.2.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

[Bug bootstrap/33070] Bootstrap comparison failure between stage2/3 but no objdump differences

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33070

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2012-01-28
     Ever Confirmed|0                           |1

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-01-28 03:08:30 UTC ---
Does this work now?  Also maybe the debugging info is different.