https://sourceware.org/bugzilla/show_bug.cgi?id=27303
Bug ID: 27303
Summary: gold/testsuite/initpri3. test fails on gold and lld,
passes on bfd. Which one is correct?
Product: binutils
Version: 2.36
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: admin
Assignee: unassigned at sourceware dot org
Reporter: slyfox at inbox dot ru
Target Milestone: ---
The test fails as is on gold:
$ gcc-11.0.0 initpri3.c -o bug -fuse-ld=lld && ./bug
bug: initpri3.c:78: main: Assertion `i == 3' failed.
Aborted (core dumped)
$ gcc-11.0.0 initpri3.c -o bug -fuse-ld=gold && ./bug
bug: initpri3.c:40: ctor2: Assertion `i == 2' failed.
Aborted (core dumped)
$ gcc-11.0.0 initpri3.c -o bug -fuse-ld=bfd && ./bug
It looks like the difference here is how the array of `.ctors` is handled:
```
/* The .ctors section is run in reverse order, the .dtors section in
run in forward order. We give these arrays the "aligned" attribute
because the x86_64 ABI would otherwise give them a 16-byte
alignment, which may leave a hole in the section. */
void (*ctors[]) (void)
__attribute__ ((aligned (4), section (".ctors"))) = {
ctor2,
ctor1
};
```
The array is stored as one section:
```
.section .ctors,"aw"
.align 8
.type ctors, @object
.size ctors, 16
ctors:
.quad ctor2
.quad ctor1
```
In both cases linker reordered the elements within the array:
$ gcc-11.0.0 initpri3.c -fuse-ld=gold -o ig -ggdb3
$ gcc-11.0.0 initpri3.c -fuse-ld=bfd -o ib -ggdb3
$ gdb --quiet ./ib
Reading symbols from ./ib...
(gdb) print ctors
$1 = {0x1139 <ctor1>, 0x117d <ctor2>}
$ gdb --quiet ./ig
Reading symbols from ./ig...
(gdb) print ctors
$1 = {0x689 <ctor1>, 0x6cd <ctor2>}
But not within __init_array_start:
$ gdb --quiet ./ib
Reading symbols from ./ib...
(gdb) start
Temporary breakpoint 1 at 0x124d: file initpri3.c, line 78.
Starting program: /tmp/z/ib
Temporary breakpoint 1, main () at initpri3.c:78
78 assert (i == 3);
(gdb) x/4a __init_array_start
0x555555557dc8: 0x555555555130 0x555555555139 <ctor1>
0x555555557dd8 <ctors+8>: 0x55555555517d <ctor2> 0x5555555550f0
gdb --quiet ./ig
Reading symbols from ./ig...
(gdb) start
Temporary breakpoint 1 at 0x79d: file initpri3.c, line 78.
Starting program: /tmp/z/ig
ig: initpri3.c:40: ctor2: Assertion `i == 2' failed.
Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:49
49 return ret;
(gdb) x/4a __init_array_start
0x555555555db8: 0x555555554680 0x5555555546cd <ctor2>
0x555555555dc8 <ctors+8>: 0x555555554689 <ctor1> 0x3
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