https://llvm.org/bugs/show_bug.cgi?id=31179
Bug ID: 31179
Summary: wrong code with "opt -loop-rotate -gvn -jump-threading
-instcombine -lcssa -loop-vectorize -lcssa
-loop-unroll -instcombine"
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: s...@cs.ucdavis.edu
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
$ clang -v
clang version 4.0.0 (trunk 287975)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/clang-trunk/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
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/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.2.0
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 -c -emit-llvm -o small.bc small.c
$ opt -loop-rotate -gvn -jump-threading -instcombine -lcssa -loop-vectorize
-lcssa -loop-unroll -instcombine -o small-opt.bc small.bc
$ llc -o small.s small-opt.bc
$ gcc small.s
$ ./a.out
Floating point exception (core dumped)
$
$ clang -O0 small.c
$ ./a.out
$
---------------------------------------
int printf (const char *, ...);
int a[128], b, e, g;
short c, d;
int main ()
{
int f = 0, h = 5;
for (; f < 128; f++)
a[f] = f;
L:
c = b / h;
e = d;
if (d)
h = 0;
if (d < g)
{
printf ("%d\n", d);
goto L;
}
return 0;
}
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