[Bug tree-optimization/102706] [12 regression] -O2 vectorization causes regression in Warray-bounds-48.c on many targets

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102706

--- Comment #3 from Hongtao.liu <crazylht at gmail dot com> ---
>From gcc.dg/Warray-bounds-51.c

void test_struct_char_vla_location (void)
{
  unsigned nelts = 7;

  struct {
    char cvla[nelts]; // { dg-message "declared here|while referencing" }
  } s;

  s.cvla[0] = __LINE__;
  s.cvla[nelts - 1] = 0; // { dg-warning "\\\[-Wstringop-overflow" "" { target
{ i?86-*-* x86_64-*-* } } }
  s.cvla[nelts] = 0;  // { dg-warning "\\\[-Warray-bounds" }

  sink (&s);
}

>From gcc.dg/Warray-parameter-3.c

__attribute__ ((noipa)) void
gcas3 (char a[static 3])
{
  a[0] = 0; a[1] = 1; a[2] = 2; // { dg-warning "\\\[-Wstringop-overflow" "" {
target { i?86-*-* x86_64-*-* } } }
  a[3] = 3;                   // { dg-warning "\\\[-Warray-bounds" }
}

>From gcc.dg/Wstringop-overflow-14.c

void test_int16 (void)
{
  char *p = a4 + 1;

  *(int16_t*)p = 0;    // { dg-warning "writing 4 bytes into a region of size
3" "" { target { i?86-*-* x86_64-*-* } } }
  *(int16_t*)(p + 2) = 0;   // { dg-warning "writing 2 bytes into a region of
size 1" "" { xfail { i?86-*-* x86_64-*-* } } }
}

>From gcc.dg/Wstringop-overflow-21.c

void test_store_zero_length (int i)
{
  char a[3];
  struct S0 *p = (struct S0*)a;
  p->a = 0;                         // { dg-warning "\\\[-Wstringop-overflow"
"" { target { i?86-*-* x86_64-*-* } } }
  p->b[0] = 0;
  p->b[1] = 1;                      // { dg-bogus "\\\[-Wstringop-overflow" }
  p->b[2] = 2;                      // { dg-warning "\\\[-Wstringop-overflow"
"" { xfail { i?86-*-* x86_64-*-* } } }
  p->b[i] = 2;
  sink (p);
}


void test_store_flexarray (int i)
{
  char a[3];
  struct Sx *p = (struct Sx*)a;
  p->a = 0;                         // { dg-warning "\\\[-Wstringop-overflow"
"" { target { i?86-*-* x86_64-*-* } } }
  p->b[0] = 0;
  p->b[1] = 1;                      // { dg-bogus "\\\[-Wstringop-overflow" }
  p->b[2] = 1;                      // { dg-warning "\\\[-Wstringop-overflow"
"" { xfail { i?86-*-* x86_64-*-* } } }
  p->b[i] = 2;
  sink (p);
}

>From gcc.dg/Wstringop-overflow-76.c:

extern char a3[3];
extern char a5[5];  // { dg-message "at offset \[^a-zA-Z\n\r\]*5\[^a-zA-Z0-9\]*
into destination object 'a5' of size 5" "note" }

void max_a3_a5 (int i)
{
  char *p = a3 + i;
  char *q = a5 + i;

  /* The relational expression below is invalid and should be diagnosed
     by its own warning independently of -Wstringop-overflow.  */
  char *d = MAX (p, q);
  d[2] = 0;         // { dg-warning "writing 4 bytes into a region of size 3"
"" { target { i?86-*-* x86_64-*-* } } }
  d[3] = 0;
  d[4] = 0;
  d[5] = 0;         // { dg-warning "writing 1 byte into a region of size 0" ""
{ xfail { i?86-*-* x86_64-*-* } } }
}


// Same as above but with the larger array as the first MAX_EXPR operand.
extern char b4[4];
extern char b6[6];  // { dg-message "at offset \[^a-zA-Z\n\r\]*6\[^a-zA-Z0-9\]*
into destination object 'b6' of size 6" "note" }

void max_b6_b4 (int i)
{
  char *p = b6 + i;
  char *q = b4 + i;
  char *d = MAX (p, q);
  d[3] = 0;         // { dg-warning "writing 4 bytes into a region of size 3"
"" { target { i?86-*-* x86_64-*-* } } }
  d[4] = 0;
  d[5] = 0;
  d[6] = 0;         // { dg-warning "writing 1 byte into a region of size 0" ""
{ xfail { i?86-*-* x86_64-*-* } } }
}