* Manuel Lauss: > On Mon, Dec 13, 2021 at 2:04 PM Florian Weimer <fweimer@xxxxxxxxxx> wrote: >> >> * Manuel Lauss via Gcc-help: >> >> > Now the descriptions of "vmovdqa" I could find say that it generates a >> > #GP when the destination is not 16-byte aligned. Does this alignment >> > include the displacement, like above? If yes, is this then a code >> > generation bug in gcc? >> >> If your build uses vector instructions, you need to build glibc with >> -mstackrealign for compatibility with legacy i386 applications. > > I read that gcc-12 enables "-ftree-vectorize" with -O2 by default, and > indeed a glibc snapshot built with gcc-12 and "-O2 -march=haswell" > suffers now from the same problem. Should "-mstackrealign" be added > to 32bit x86 build unconditionally? I think it's just something you need to know when building glibc for legacy applications. Most users will likely prefer full optimization for their builds (otherwise they wouldn't build with -march=haswell). Thanks, Florian
