On Tue, Mar 08, 2022 at 12:15:15PM +0100, Jakub Jelinek via Gcc-patches wrote: > > --- gcc/config/i386/i386.h.jj 2022-02-25 12:06:45.535493490 +0100 > > +++ gcc/config/i386/i386.h 2022-03-08 11:20:43.207043370 +0100 > > @@ -2848,6 +2848,10 @@ extern enum attr_cpu ix86_schedule; > > #define NUM_X86_64_MS_CLOBBERED_REGS 12 > > #endif > > > > +/* __builtin_eh_return can't handle stack realignment, so disable SSE in > > + libgcc functions that call it. */ > > +#define LIBGCC2_UNWIND_ATTRIBUTE __attribute__((target ("no-sse"))) > > + > > /* > > Local variables: > > version-control: t > > > > > > As mentioned in PR104838, this likely isn't specific to just Solaris and > > cygwin/mingw. Fedora uses -msse2 -mfpmath=sse -mstackrealign in its > > C{,XX}FLAGS > > among other things for i686. > > Now verified that with your full patch applied gcc on Fedora/i686 doesn't > build (gets those sorry messages when compiling unwind-dw2), while if I > replace those 2 libgcc hunks from your patch with the above one it seems to > get past the previous hanging point of gnat1 processes.
Though, perhaps it should be #ifndef __x86_64__ #define LIBGCC2_UNWIND_ATTRIBUTE __attribute__((target ("no-sse"))) #endif or something similar, on x86-64 one at least normally doesn't use lower stack realignment unless avx or later. Maybe we want to use no-avx for the x86-64 case though. Disabling sse/sse2 might be a problem especially on mingw where we need to restore SSE registers in the EH return, no? Even better would be to make __builtin_eh_return work even with DRAP, but I admit I haven't understood what exactly is the problem that prevents it from working. Jakub