mirror of
https://git.musl-libc.org/git/musl
synced 2025-02-13 16:54:16 +03:00
bdb0817599
we have to avoid using ebx unconditionally in asm constraints for i386, because gcc 3 and 4 and possibly other simplistic compilers (pcc?) implement PIC via making ebx a fixed-use register, and disallow its use for anything else. rather than hard-coding knowledge of which compilers work (at least gcc 5+ and clang), perform a configure test; this should give us the good codegen on any new compilers we don't yet know about. swapping ebx and edx is kept for 1- and 2-arg syscalls because it avoids having any spills/stack-frame at all in small functions. for 6-arg, if ebx is directly usable, the complex shuffling introduced in commit c8798ef974d21c338a7d8d874a402978ffc6168e can be avoided, and ebp can be loaded the same way ebx is in 5-arg syscalls for compilers that don't support direct use of ebx.