[llvm-bugs] [Bug 49785] New: Infinite loop at -O3

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49785

            Bug ID: 49785
           Summary: Infinite loop at -O3
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: haoxintu at gmail.com
                CC: llvm-bugs at lists.llvm.org

Hi all.

$cat small.c
#include <stdint.h>
int a, b, c, d;
uint16_t e;
void f() {
  uint16_t *g = &e;
  int8_t *i = &a;
  for (c = 5; c <= 63; c++)
    for (*g = 9; *g <= 60; *g += 1)
      if ((e ^ b) != d) {
        int8_t *j = a;
        for (*j = 3; *j <= 32; *j += 1)
          if (*j)
            for (*i = 1; *i <= 30;)
              *i &= 0 == c;
      }
}

$clang -w -O3 small.c
//endless compiling

$clang -v
clang version 13.0.0 (https://github.com/llvm/llvm-project
850fcedb272ff07ac46b9880e628caec2de3eb2c)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir:
/home/haoxin/haoxin-data/dut-research/compilers/llvm-project/build-20210330/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Candidate multilib: .;@m64
Selected multilib: .;@m64


Thanks,
Haoxin

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