[Bug target/106069] [12/13 Regression] wrong code with -O -fno-tree-forwprop -maltivec on ppc64le

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106069

--- Comment #4 from luoxhu at gcc dot gnu.org ---
Reduced to:

#include <stdio.h>
extern "C" void *memcpy(void *, const void *, unsigned long);
typedef __attribute__((altivec(vector__))) unsigned native_simd_type;

union {
        native_simd_type V;
        int R[4];
} store_le_vec;

struct S {
        S() = default;
        S(unsigned B0) {
                native_simd_type val{B0};
                m_simd = val;
        }
        void store_le(unsigned char out[]) {
                store_le_vec.V = m_simd;
                unsigned int x0 = store_le_vec.R[0];
                memcpy(out, &x0, 1);
        }
        static void transpose(S &B0, S B1, S B2, S B3) {
                native_simd_type T0 = __builtin_vec_mergeh(B0.m_simd,
B2.m_simd);
                native_simd_type T1 = __builtin_vec_mergeh(B1.m_simd,
B3.m_simd);
                native_simd_type T2 = __builtin_vec_mergel(B0.m_simd,
B2.m_simd);
                native_simd_type T3 = __builtin_vec_mergel(B1.m_simd,
B3.m_simd);
                B0 = __builtin_vec_mergeh(T0, T1);
                B3 = __builtin_vec_mergel(T2, T3);
                printf ("B0: %x, %x,%x,%x\n", B0.m_simd[0], B0.m_simd[1],
B0.m_simd[2], B0.m_simd[3]);
        }
        S(native_simd_type x) : m_simd(x) {}
        native_simd_type m_simd;
};

        void
foo (unsigned char output[], unsigned state[], native_simd_type R0,
native_simd_type R1, native_simd_type R2, native_simd_type R3)
{
        S R00; R00.m_simd = R0;
        S R01; R01.m_simd = R1;
        S R02; R02.m_simd = R2;
        S R03; R03.m_simd = R3;
        S::transpose(R00, R01, R02, R03);
        R00.store_le(output);
}

unsigned char res[1];
unsigned main_state[]{1634760805, 60878,      2036477234, 6,
        0,          825562964,  1471091955, 1346092787,
        506976774,  4197066702, 518848283,  118491664,
        0,          0,          0,          0};
int
main ()
{
        native_simd_type R0 = native_simd_type {0x41fcef98, 0,0,0};
        native_simd_type R1 =  native_simd_type {0x91648e8b, 0,0,0};
        native_simd_type R2 = native_simd_type  {0x7dca18c6, 0,0,0};
        native_simd_type R3 = native_simd_type  {0x61707865, 0,0,0};
        foo (res, main_state, R0, R1, R2, R3);
        if (res[0] != 152)
                __builtin_abort();
}