[Bug tree-optimization/102462] vectorization breaks diagnostic for array out of bound detect.

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102462

--- Comment #9 from Hongtao.liu <crazylht at gmail dot com> ---
case 1: All accesses are out of bound, and after vectorization, there are
some warnings missing.(Because there only 1 access after vectorization, 2
accesses w/o vectorization, and diagnostic is based on access).

from c-c++-common/Wstringop-overflow-2.c
struct A1 a1__ = { 0 };

void ga1__ (void)
{
  a1__.a[0] = 0;
  a1__.a[1] = 1;                 // { dg-warning "\\\[-Wstringop-overflow" }
  a1__.a[2] = 2;                 // { dg-warning "\\\[-Wstringop-overflow" }

  struct A1 a = { 1 };
  a.a[0] = 0;
// After vectorization, below codes are optimized to
// vector(2) char = { 1, 2}, there's only 1 access remained, so add xfail
// to a.a[2] = 2, refer to pr102462.
  a.a[1] = 1;                    // { dg-warning "\\\[-Wstringop-overflow" }
  a.a[2] = 2;                    // { dg-warning "\\\[-Wstringop-overflow" "" {
xfail { i?86-*-* x86_64-*-* } } }
  sink (&a);
}

struct A1 a1_0 = { 0, { } };

void ga1_0_ (void)
{
  a1_0.a[0] = 0;
  a1_0.a[1] = 1;                // { dg-warning "\\\[-Wstringop-overflow" }
  a1_0.a[2] = 2;                // { dg-warning "\\\[-Wstringop-overflow" }

  struct A1 a = { 1, { } };
  a.a[0] = 0;
  a.a[1] = 1;                   // { dg-warning "\\\[-Wstringop-overflow" }
  a.a[2] = 2;                   // { dg-warning "\\\[-Wstringop-overflow" "" {
xfail { i?86-*-* x86_64-*-* } } }
  sink (&a);
}

struct A1i a1i__ = { 0 };

void ga1i__ (void)
{
  a1i__.a[0] = 0;
  a1i__.a[1] = 1;                // { dg-warning "\\\[-Wstringop-overflow" }
  a1i__.a[2] = 2;                // { dg-warning "\\\[-Wstringop-overflow" }

  struct A1i a = { 0 };
  a.a[0] = 0;
  a.a[1] = 1;                    // { dg-warning "\\\[-Wstringop-overflow" }
  a.a[2] = 2;                    // { dg-warning "\\\[-Wstringop-overflow" "" {
xfail { i?86-*-* x86_64-*-* } } }
  sink (&a);
}

struct A1 a1i_0 = { 0, { } };

void ga1i_0_ (void)
{
  a1i_0.a[0] = 0;
  a1i_0.a[1] = 1;               // { dg-warning "\\\[-Wstringop-overflow" }
  a1i_0.a[2] = 2;               // { dg-warning "\\\[-Wstringop-overflow" }

  struct A1 a = { 0, { } };
  a.a[0] = 0;
  a.a[1] = 1;                   // { dg-warning "\\\[-Wstringop-overflow" }
  a.a[2] = 2;                   // { dg-warning "\\\[-Wstringop-overflow" "" {
xfail { i?86-*-* x86_64-*-* } } }
  sink (&a);
}