http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59679
Bug ID: 59679
Summary: gcc version 4.7.3 and gcc version 4.5.3 cause an
unaligned access exception on NetBSD/Alpha
Product: gcc
Version: 4.7.3
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: nullnilaki at gmail dot com
Using gcc4.7.3 and gcc4.5.3 to compile a Perl v5.18.1.
Perl cause an unaligned access exception.
----------------------------------------------------------------
Please read the perl-bug
https://rt.perl.org/Public/Bug/Display.html?id=120888
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gcc4.5 and gcc4.7 cause this problem.
(I can not compile gcc4.6 and gcc4.8 but I think gcc4.6 and gcc4.8 has some
kind of similar bug.)
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This problem was caused by compiler's bug. -ftree-ter option makes wrong
binary.
----------------------------------------------------------------
-O2 version.
(gdb) break scope.c:1217
No source file named scope.c.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (scope.c:1217) pending.
(gdb) r perl.pl
Starting program: /usr/pkg/bin/perl perl.pl
[Switching to LWP 1]
Breakpoint 1, Perl_leave_scope (my_perl=0x160505000, base=<optimized out>) at
scope.c:1217
1217 *(I8*)ARG0_PTR = (I8)(uv >> 8);
(gdb) list
1212
1213 case SAVEt_I16: /* I16 reference */
1214 *(I16*)ARG0_PTR = (I16)(uv >> 8);
1215 break;
1216 case SAVEt_I8: /* I8 reference */
1217 *(I8*)ARG0_PTR = (I8)(uv >> 8);
1218 break;
1219 case SAVEt_DESTRUCTOR:
1220 (*arg1.any_dptr)(ARG0_PTR);
1221 break;
(gdb) x/10i $pc
=> 0x1601795c0 <Perl_leave_scope+3648>: extbl t5,0x1,t5
0x1601795c4 <Perl_leave_scope+3652>: ldl t0,0(s1)
0x1601795c8 <Perl_leave_scope+3656>: andnot t0,0xff,t0
0x1601795cc <Perl_leave_scope+3660>: or t5,t0,t5
0x1601795d0 <Perl_leave_scope+3664>: stl t5,0(s1)
0x1601795d4 <Perl_leave_scope+3668>: ldl t3,48(s0)
0x1601795d8 <Perl_leave_scope+3672>: ldl t0,152(s0)
0x1601795dc <Perl_leave_scope+3676>: br 0x160178800
<Perl_leave_scope+128>
0x1601795e0 <Perl_leave_scope+3680>: mov s0,a0
0x1601795e4 <Perl_leave_scope+3684>: ldq t12,-24984(gp)
(gdb) p uv
$1 = 2574
(gdb) ptype uv
type = long unsigned int
(gdb) ptype I8
type = signed char
(gdb) print /a uv
$2 = 0xa0e
(gdb) p arg0
$1 = {any_ptr = 0x1605104ee, any_i32 = 1615922414, any_iv = 5910889710, any_uv
= 5910889710, any_long = 5910889710, any_bool = 238,
any_dptr = 0x1605104ee, any_dxptr = 0x1605104ee}
(gdb) p &arg0
Address requested for identifier "arg0" which is in register $s1
(gdb) n
pid 436 (perl): unaligned access: va=0x1605104ee pc=0x1601795c4 ra=0x160179124
sp=0x1ffffc698 op=ldl
pid 436 (perl): unaligned access: va=0x1605104ee pc=0x1601795d0 ra=0x160179124
sp=0x1ffffc698 op=stl
1218 break;
1218 break;
(gdb) p uv
$1 = <optimized out>
-------------------------------------------------------------------
-O2 -fno-tree-ter version.
(gdb) break scope.c:1217
No source file named scope.c.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (scope.c:1217) pending.
(gdb) r perl.pl
Starting program: /usr/pkg/bin/perl perl.pl
[Switching to LWP 1]
Breakpoint 1, Perl_leave_scope (my_perl=0x160505000, base=<optimized out>) at
scope.c:1217
1217 *(I8*)ARG0_PTR = (I8)(uv >> 8);
(gdb) x/10i $pc
=> 0x160177df0 <Perl_leave_scope+3664>: extbl t5,0x1,t5
0x160177df4 <Perl_leave_scope+3668>: ldq_u t0,0(s1)
0x160177df8 <Perl_leave_scope+3672>: insbl t5,s1,t5
0x160177dfc <Perl_leave_scope+3676>: mskbl t0,s1,t0
0x160177e00 <Perl_leave_scope+3680>: or t5,t0,t5
0x160177e04 <Perl_leave_scope+3684>: stq_u t5,0(s1)
0x160177e08 <Perl_leave_scope+3688>: ldl t3,48(s0)
0x160177e0c <Perl_leave_scope+3692>: ldl t0,152(s0)
0x160177e10 <Perl_leave_scope+3696>: br 0x160177020
<Perl_leave_scope+128>
0x160177e14 <Perl_leave_scope+3700>: unop
(gdb) p uv
$1 = 2574
(gdb) ptype uv
type = long unsigned int
(gdb) ptype I8
type = signed char
(gdb) print /a uv
$2 = 0xa0e
(gdb) p arg0
$1 = {any_ptr = 0x1605104ee, any_i32 = 1615922414, any_iv = 5910889710, any_uv
= 5910889710, any_long = 5910889710, any_bool = 238,
any_dptr = 0x1605104ee, any_dxptr = 0x1605104ee}
(gdb) n
1218 break;
