https://llvm.org/bugs/show_bug.cgi?id=24535
Bug ID: 24535
Summary: wrong code at -O3 on x86_64-linux-gnu in 32-bit mode
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
Assignee: unassignedclangb...@nondot.org
Reporter: s...@cs.ucdavis.edu
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
The following code is miscompiled by the current clang trunk on
x86_64-linux-gnu at -O3 in 32-bit mode (but not in 64-bit mode).
This is a regression from 3.6.x.
$ clang-trunk -v
clang version 3.8.0 (trunk 245675)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
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/4.8.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.1.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$
$ clang-trunk -m32 -O2 small.c; ./a.out
-1
$ clang-trunk -m64 -O3 small.c; ./a.out
-1
$ clang-3.6 -m32 -O3 small.c; ./a.out
-1
$
$ clang-trunk -m32 -O3 small.c
$ ./a.out
127
$
----------------------------------
int printf (const char *, ...);
int a, b, d, e, f, g;
char c;
void
fn1 (int p)
{
for (b = 1; b; b = a)
g = c ? c : p ? 0 : a;
}
int
main ()
{
c--;
fn1 (0);
d--;
a = e && f;
d && (e = 0);
printf ("%d\n", c);
return 0;
}
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