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https://bugzilla.novell.com/show_bug.cgi?id=638750

https://bugzilla.novell.com/show_bug.cgi?id=638750#c0


           Summary: Bug in GCC: generates wrong Code whem optimizing
    Classification: openSUSE
           Product: openSUSE 11.3
           Version: Final
          Platform: x86-64
        OS/Version: openSUSE 11.3
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Development
        AssignedTo: pth@xxxxxxxxxx
        ReportedBy: Ralf.Friedl@xxxxxxxxx
         QAContact: qa@xxxxxxx
          Found By: ---
           Blocker: ---


User-Agent:       Mozilla/5.0 (Windows; U; Win98; de-AT; rv:1.8.1.24)
Gecko/20100228 SeaMonkey/1.1.19

Compiler: gcc (SUSE Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292]

When compiling mksquashfs from squashfs3.4, the compiler generates wrong code
with -O2 in function create_inode in file
squashfs3.4/squashfs-tools/mksquashfs.c. The function makes use of some similar
but different, longer macros in different branches of the function. With
-fno-tree-pta, the code works.

The compiler even generates unaligned overlapping like "movl $0,0; movl $0,1;".
The second assign is both unaligned and overlaps three bytes of the long
starting at 0. The generated code first computes the right value and then
overwrites it with 0 with these instructions.

The bug affects both i586 and x86-64.

This bug may be related to Bug 636118 - "gcc 4.5 breaks mozilla's libffi
implementation", or maybe not, because it mentions "It only fails for i586 but
not x86-64."

gcc (SUSE Linux) 4.5.0 20100722 [gcc-4_5-branch revision 162408] produces
working code.

If you are interested, I can supply the preprocessor output and the assembly
file, but as the bug seems to be already fixed in newer versions of gcc, I
suggest to just update the compiler to a newer version.

Reproducible: Always

Steps to Reproduce:
1. Compile mksquashfs
2. Create squashfs file system.
3. File system is corrupt.
Actual Results:  
Generated file system is corrupt.

Expected Results:  
Generated file system is not corrupt.

This bug has affected different people on different systems with i586 and
x86-64 on Intel and AMD CPUs who tried to use this program.

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