[Bug target/33848] [4.2 Regression] undefined reference to `$L2120' at -O1 on mips/mipsel

["tbm at cyrius dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #1 from tbm at cyrius dot com  2007-10-21 09:46 -------
The problem is that gcc-4.2 generates a bne instruction that references a
label that doesn't exist.  This happens with -O1 or higher.  It doesn't
happen with gcc 4.1 or current trunk.

If you compile the attached preprocessed source and look at the assembler
code you'll see it.  Search for L2043 when you compile with -O1, for
L2120 with -O2.

% gcc-4.2 -c -S -O1 erlang-beam_emu.i

Looking at erlang-beam_emu.s, we get

$L2042:
        sw      $0,44($sp)
        sw      $19,0($21)
        sw      $20,4($21)
        lw      $25,%got(save_reg.15912)($28)
        nop
        sw      $23,%lo(save_reg.15912)($25)
        lw      $22,60($21)
        nop
        lw      $2,0($22)
        lw      $3,%got($L2035)($28)
        nop
        addiu   $3,$3,%lo($L2035)
        bne     $2,$3,$L2043
        nop

        addiu   $2,$20,8
        beq     $2,$0,$L2049
        move    $17,$0

$L2637:


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33848