[Bug middle-end/66741] New: loops not fused nor vectorized

["aldot at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66741

            Bug ID: 66741
           Summary: loops not fused nor vectorized
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aldot at gcc dot gnu.org
            Blocks: 53947
  Target Milestone: ---

I would have hoped that the strcpy loop and &~0x20 loop would be fused,
perusing some masked store for the tolower.

$ cat > strcpy.c <<EOF
typedef __SIZE_TYPE__ size_t;
char *tolower_strcpy(char *dest, const char *src) {
        char *ret = __builtin_strcpy(dest, src);
#if 1
        size_t sz = __builtin_strlen(dest);
        while (sz--)
#else
        while (*ret)
#endif
        {
                int ch = *ret;
                *ret = __builtin_tolower(ch);
                ++ret;
        }
        return dest;
}
#ifdef MAIN
#include <unistd.h>
#include <string.h>
int main(void) {
        char src[128], dest[128];
        int n = read(0, &src, sizeof(src));
        if (n < 1)
                return 1;
        src[n] = 0;
        tolower_strcpy(dest, src);
        write(2, dest, strlen(dest));
        return 0;
}
#endif
EOF

gcc-5 -S strcpy.c -o strcpy.s -Ofast -fomit-frame-pointer
-minline-all-stringops -mstringop-strategy=unrolled_loop -mtune=ivybridge


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations