[Bug target/110598] [14 Regression] wrong code on llvm-14.0.6 due to memcmp being miscompiled

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110598

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is a C testcase:
```
#include <stdbool.h>

typedef unsigned long long u64;

#define MAX_SUBTARGET_WORDS 4

//[[gnu::noipa]]
int notequal(const void *a, const void *b)
{
        return __builtin_memcmp(a,b,MAX_SUBTARGET_WORDS*sizeof(u64)) != 0;
}
typedef struct FeatureBitset {
  u64 Bits[MAX_SUBTARGET_WORDS];
}FeatureBitset;

__attribute__((noipa))
bool is_eq_buggy (const FeatureBitset * lf, const FeatureBitset * rf) {
        u64 Bits_l[MAX_SUBTARGET_WORDS];
        Bits_l[0] = lf->Bits[0]&1;
        Bits_l[1] = 0;
        Bits_l[2] = 0;
        Bits_l[3] = 0;
        u64 Bits_r[MAX_SUBTARGET_WORDS];
        Bits_r[0] = rf->Bits[0]&1;
        Bits_r[1] = 0;
        Bits_r[2] = 0;
        Bits_r[3] = 0;
        return !notequal(Bits_l, Bits_r);
}

__attribute__((noipa))
void bug(void) {
    FeatureBitset lf, rf;
    lf.Bits[0] = rf.Bits[0] = 1;
    lf.Bits[1] = rf.Bits[1] = 1;
    lf.Bits[2] = rf.Bits[2] = 1;
    lf.Bits[3] = rf.Bits[3] = 1;

    bool r = is_eq_buggy (&lf, &rf);
    if (!r) __builtin_trap();
}

__attribute__((noipa))
int main(void) {
    bug();
}
```

Again uncomment the attribute on notequal, if you want to see it works without
inlining of memcmp here ...