http://llvm.org/bugs/show_bug.cgi?id=18862
Bug ID: 18862
Summary: wrong code at -O1 and above on x86_64-linux-gnu in
32-bit mode (for code with the "pack" pragma and
bitfields)
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
The following code is miscompiled by the current clang trunk at -O1 and above
in 32-bit mode (but not 64-bit) on x86_64-linux-gnu.
This is a regression from 3.4.
$ clang-trunk -v
clang version 3.5 (trunk 201494)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multiilb: .;@m64
Candidate multiilb: 32;@m32
Selected multilib: .;@m64
$
$ clang-trunk -m32 -O0 small.c; a.out
0
-2
$ clang-trunk -m64 -O1 small.c; a.out
0
-2
$ clang-3.4 -m32 -O1 small.c; a.out
0
-2
$
$ clang-trunk -m32 -O1 small.c; a.out
0
-1
$
--------------------------------
int printf (const char *, ...);
#pragma pack(1)
struct
{
int f0:9;
int f1:30;
int f2:5;
int f3:23;
int f4:11;
int f5:29;
int f6:24;
int:14;
} a, b = {0, 0, 0, 0, 0, 0, -2};
int c;
int
main ()
{
printf ("%d\n", a.f6);
for (; c < 1; c++)
printf ("%d\n", b.f6);
return 0;
}
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