[Bug tree-optimization/118149] [15 regression] ICE when building lsp-plugins-1.2.14 (mmap: Cannot allocate memory in forwprop)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118149

--- Comment #4 from Sam James <sjames at gcc dot gnu.org> ---
Reduced:
```
float *fastconv_parse_dst;
void fastconv_parse() {
  float r3k = fastconv_parse_dst[1] - fastconv_parse_dst[3],
        i0k = fastconv_parse_dst[4] + fastconv_parse_dst[6],
        i1k = fastconv_parse_dst[4] - fastconv_parse_dst[6],
        i2k = fastconv_parse_dst[5] + fastconv_parse_dst[7];
  fastconv_parse_dst[1] = fastconv_parse_dst[0];
  fastconv_parse_dst[4] = fastconv_parse_dst[5] = i0k - i2k;
  fastconv_parse_dst[6] = fastconv_parse_dst[7] = i1k + r3k;
}
```

Just '-O2' is enough.