[Bug target/108804] missed vectorization in presence of conversion from uint64_t to float

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108804

--- Comment #3 from Hongtao.liu <crazylht at gmail dot com> ---
I think the point here is: although it's unit64_t -> float, but the range of x
and y can be represent as int32(k & 0x007FFFFF) |  0x3F800000), so we can use
int32 -> float instructions which are supported by the backend.

So it looks to me a middle-end issue.

A simple testcase clang generates vcvtdq2ps but gcc doesn't vectorize.

#include<stdint.h>

uint64_t d[512];
float f[1024];

void foo() {
    for (int i=0; i<512; ++i) {
        uint64_t k = d[i];
        f[i]=(k & 0x3F30FFFF);
    }
}

manually add convertion then gcc also can do vectorization.

#include<stdint.h>

uint64_t d[512];
float f[1024];

void foo() {
    for (int i=0; i<512; ++i) {
        uint64_t k = d[i];
        f[i]=(int)(k & 0x3F30FFFF);
    }
}