When assembled, a jump to weak symbol produces a jump to an invalid address. I
found that problem on m68k-unknown-netbsd, but it may affect all m68k-*-aout
targets.
$ cat bug.s
jmp mylabel
nop
.weak mylabel
mylabel:
nop
$ as bug.s -o bug.o
$ objdump -d bug.o
bug.o: file format a.out-m68k-netbsd
Disassembly of section .text:
00000000 <mylabel-0x6>:
0: 4efa 000a jmp %pc@(c <mylabel+0x6>)
4: 4e71 nop
00000006 <mylabel>:
6: 4e71 nop
The value of the jmp instruction is wrong : it should be %pc@(6 <mylabel>)
It might not be a problem, because there is a relocation.
$ objdump -r bug.o
bug.o: file format a.out-m68k-netbsd
RELOCATION RECORDS FOR [.text]:
OFFSET TYPE VALUE
00000002 DISP16 .text
Here, it is clearly wrong. The relocation offset is good, but the value should
be "mylabel" instead of ".text"
After linking, there is no more relocation, but the value of the jump is still
bad.
The same problem was present in gas 2.14 for m68k-unknown-netbsd (already using
BFD).
The problem was not present in gas 2.14 for m68k-linux-aout (not using BFD) :
$ objdump -d bug.o # binutils 2.14 m68k-linux-aout
bug.o: file format a.out-zero-big
Disassembly of section .text:
00000000 <mylabel-0x6>:
0: 4efa 0004 jmp %pc@(6 <mylabel>)
4: 4e71 nop
00000006 <mylabel>:
6: 4e71 nop
I think the above result is correct and the current version of gas for m68k-
unknown-netbsd should behave like that.
--
Summary: Bogus jump to weak symbol on m68k-unknown-netbsd
Product: binutils
Version: 2.18 (HEAD)
Status: NEW
Severity: normal
Priority: P2
Component: gas
AssignedTo: unassigned at sources dot redhat dot com
ReportedBy: vincent dot riviere at freesbee dot fr
CC: bug-binutils at gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: m68k-unknown-netbsd
http://sourceware.org/bugzilla/show_bug.cgi?id=3041
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