slp-vectorizer cannot terminate

Quuxplusone commented 5 years ago


Bugzilla Link	PR41289
Status	NEW
Importance	P enhancement
Reported by	Zhide Zhou (cszide@163.com)
Reported on	2019-03-28 23:49:06 -0700
Last modified on	2019-03-29 02:03:22 -0700
Version	trunk
Hardware	PC Linux
CC	a.bataev@hotmail.com, dtemirbulatov@gmail.com, llvm-bugs@lists.llvm.org
Fixed by commit(s)
Attachments	`small.bc` (6424 bytes, application/octet-stream) `small-opt.bc` (834400 bytes, application/octet-stream)
Blocks
Blocked by
See also

Created attachment 21696
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 355281)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build4/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

$clang -O3 -c -emit-llvm  -mllvm -disable-llvm-optzns small.c

$opt -gvn -structurizecfg  small.bc -o small-opt.bc

$opt -slp-vectorizer  small-opt.bc
In this step, opt will consume too much memory and not terminate.

By using godbolt, it shows that the llvm 6/7/truck version also has this
problem.

-----------------------------------------
struct {
  int a;
  int b;
  int c
} * d, e, f, g, h;
fn1() {
  int j;
  int k;
  int l;
  int m;
n : {
  int o;
p:
  if (j)
    for (; e.a;) {
      int q;
      for (; h.c;) {
        int i;
        if (k)
          goto p;
        if (l)
          for (; 2; i)
            return o;
      }
    }
  int r;
  if (m)
  aa:
    if (0 & r && 0)
      for (; 0;) {
        int a;
        for (; 0;) {
          if (a)
            goto n;
          for (; f.c; f)
            goto aa;
        }
        for (; 0;)
          for (; g.b; 1)
            return d;
      }
}
}

Quuxplusone commented 5 years ago

Attached small.bc (6424 bytes, application/octet-stream): .bc file of the source code

Quuxplusone commented 5 years ago

Attached small-opt.bc (834400 bytes, application/octet-stream): optimized .bc file of source code

Quuxplusone commented 5 years ago

This may not a bug. When I test this testcase, I set the time of timeout command to 60s, but it cannot produce the result. Without the limitation of run time, opt can output the result. Maybe it is a performance problem.

Quuxplusone / LLVMBugzillaTest

slp-vectorizer cannot terminate #40259