[llvm-bugs] [Bug 41558] New: wrong code with "opt -simplifycfg -structurizecfg -inline" (generated code hangs)

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41558

            Bug ID: 41558
           Summary: wrong code with "opt   -simplifycfg  -structurizecfg
                    -inline" (generated code hangs)
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: cszide at 163.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 21812
  --> https://bugs.llvm.org/attachment.cgi?id=21812&action=edit
.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 -o small.bc

$clang small.bc -o small1.out && ./small1.out
checksum = 9add2096

$opt -simplifycfg -structurizecfg  -inline small.bc -o small-opt1.bc
$clang small-opt.bc -o small2.out && timeout -s 9 10 ./small2.out
Killed

$opt -simplifycfg -structurizecfg  small.bc -o small-opt2.bc
$ clang small-opt2.bc -o small3.out &&  ./small3.out
checksum = d8f827eb

-----------------------------------------------
//------------------------
typedef signed char             int8_t;
typedef int                     int32_t;
typedef long int                int64_t;
/* Unsigned.  */
typedef unsigned char           uint8_t;
typedef unsigned short int      uint16_t;
typedef unsigned int            uint32_t;
typedef unsigned long int       uint64_t;

static uint32_t crc32_tab[256];
static uint32_t crc32_context = 0xFFFFFFFFUL;

static void 
crc32_gentab (void)
{
        uint32_t crc;
        const uint32_t poly = 0xEDB88320UL;
        int i, j;

        for (i = 0; i < 256; i++) {
                crc = i;
                for (j = 8; j > 0; j--) {
                        if (crc & 1) {
                                crc = (crc >> 1) ^ poly;
                        } else {
                                crc >>= 1;
                        }
                }
                crc32_tab[i] = crc;
        }
}

static void 
crc32_byte (uint8_t b) {
        crc32_context = 
                ((crc32_context >> 8) & 0x00FFFFFF) ^ 
                crc32_tab[(crc32_context ^ b) & 0xFF];
}


static void 
crc32_8bytes (uint64_t val)
{
        crc32_byte ((val>>0) & 0xff);
        crc32_byte ((val>>8) & 0xff);
        crc32_byte ((val>>16) & 0xff);
        crc32_byte ((val>>24) & 0xff);
        crc32_byte ((val>>32) & 0xff);
        crc32_byte ((val>>40) & 0xff);
        crc32_byte ((val>>48) & 0xff);
        crc32_byte ((val>>56) & 0xff);
}

static void 
transparent_crc (uint64_t val, char* vname, int flag)
{
        crc32_8bytes(val);
        if (flag) {
                printf("...checksum after hashing %s : %lX\n", vname,
crc32_context ^ 0xFFFFFFFFUL);
        }
}


static inline void
platform_main_end (uint64_t x, int flag)
{
  if (!flag) {
    printf ("checksum = %llx\n", x);

  }
}

//------------------------

int a, b, c, d = 2;
uint16_t e(uint8_t);
int32_t *f(int32_t *, int32_t *, int32_t, uint8_t);
int32_t g(){}
int64_t h() {
  uint8_t k = e(0);
  return k;
}
uint16_t e(uint8_t j) {
  uint32_t *m = &a;
  uint8_t l = 0;
  f(g, m, j, j);
  return l;
}
int32_t *f(int32_t *o, int32_t *n, int32_t q, uint8_t p) {
  for (;;) {
    int i;
    for (; c <= 2;) {
      int32_t *s[9][3][9] = {&b};
      for (i = 0; i; i++)
        ;
      for (; i;)
        i = 0;
      for (d = 0; d <= 2;)
        return s[7][2][7];
    }
    for (; p; p++)
      ;
  }
}
void main() {
  int r = 0;
  crc32_gentab();
  h();
  transparent_crc(d, "", r);
  platform_main_end(crc32_context, 0);

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