On Fri, Feb 16, 2024 at 8:06 PM Pedro Falcato <pedro.falc...@gmail.com> wrote: > > On Fri, Feb 16, 2024 at 2:46 PM pawel.karczewski via groups.io > <pawel.karczewski=solidigm....@groups.io> wrote: > > > > Hi, > > > > I'm successfully building C++20 project with edk2 under the GCC compiler. > > Currently I'm trying to add edk2-libc to this project, but encountered > > issue with <string.h> header. > > > > ``` > > edk2/StdLib/Include/string.h:487:19: error: ISO C++17 does not allow > > ‘register’ storage class specifier [-Werror=register] register char > > **stringp > > ``` > > > > Why `strsep(register char **stringp, register const char *delim)` > > parameters has register storage class-class specifier? > > C standard states the `register` keyword is only hint for the compiler and > > the extent to which such > > suggestions are effective is implementation-defined. Do you see any real > > performance improvements thanks to this? > > Considering the file is Copyright(C) University of California (and the > SCCS tags suggest 1993, which places it around 4.4BSD), this very much > looks like a historical artifact (of old UNIX and bad compilers). I > certainly doubt any compiler capable of building EDK2 changes its > codegen because of it (and certainly not the calling convention, at > least in all ABIs I know of).
I was bored and had to check :) Old 4.4BSD string.h: https://www.tuhs.org/cgi-bin/utree.pl?file=4.4BSD/usr/src/include/string.h So we can see that it didn't even have the register specifier in the declaration. However, in the definition: https://www.tuhs.org/cgi-bin/utree.pl?file=4.4BSD/usr/src/lib/libc/string/strsep.c We can see that 'register' was present there, for what I assume was handholding the compiler into keeping the arg variables in registers on old UNIX (they did that *a lot*, even back in the original UNIX C versions). -- Pedro -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115564): https://edk2.groups.io/g/devel/message/115564 Mute This Topic: https://groups.io/mt/104393456/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
