http://llvm.org/bugs/show_bug.cgi?id=17781
Bug ID: 17781
Summary: wrong code at -Os and above on x86_64-linux-gnu (both
32-bit and 64-bit modes)
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: LLVM Codegen
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
The following code is miscompiled by the current clang trunk on
x86_64-linux-gnu at -Os and above in both 32-bit and 64-bit modes.
This is a regression from clang 3.3.
$ clang-trunk -v
clang version 3.4 (trunk 193897)
Target: x86_64-pc-linux-gnu
Thread model: posix
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/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
$
$ clang-trunk -O1 small.c; a.out
1
$ clang-trunk -Os small.c; a.out
0
$ clang-3.3 -Os small.c; a.out
1
$ gcc-4.8.2 -Os small.c; a.out
1
$ icc -Os small.c; a.out
1
$
---------------------------------
int printf (const char *, ...);
struct S0
{
int f0;
int f1;
int f2;
int f3;
int f4;
} b = {0, 0, 1, 0, 0};
int a;
void
foo (struct S0 p)
{
b.f2 = 0;
if (p.f2)
a = 1;
}
int
main ()
{
foo (b);
printf ("%d\n", a);
return 0;
}
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