On Mon, Dec 12, 2022 at 06:20:14PM +0800, Kewen.Lin wrote: > Without or with patch #1, the below ICE in libgcc exists, the ICE should have > nothing to do with the special handling for building_libgcc in patch #1. I > think patch #2 which makes _Float128 and __float128 use the same internal > type fixes that ICE. > > I still don't get the point why we need the special handling for > building_libgcc, > I also tested on top of patch #1 and #2 w/ and w/o the special handling for > building_libgcc, both bootstrapped and regress-tested. > > Could you have a double check?
As long as patch #2 and #3 are installed, we don't need the special handling for building_libgcc. Good catch. I will send out a replacement patch for it. > Since your patch #2 (and #3) fixes ICE and some exposed problems, and > _Float128 > is to use the same internal type as __float128, types with > attribute((mode(TF))) > and attribute((mode(TC))) should be correct, I assume that this patch is just > to make the types explicit be with _Float128 (for better readability and > maintainance), but not for any correctness issues. Yes, the patch is mainly for clarity. The history is the libgcc support went in before _Float128 went in, and I never went back to use those types when we could use them. With _Float128, we can just use _Complex _Float128 and not bother with trying to get the right KC/TC for the attribute mode stuff. However, if patches 1-3 aren't put in, just applying the patch to use _Float128 and _Complex _Float128 would fix the immediate problem (of not building GCC on systems with IEEE 128-bit long double). However, it is a band-aid that just works around the problem of building __mulkc3 and __divkc3. It doesn't fix the other problems between __float128 and _Float128 that show up in some places that I would like to get fixed. So I haven't submitted the patch, because I think it is more important to get the other issues fixed. > > Now, this patch fixes the specific problem of not being able to build libgcc > > (along with patch #1 of the series). But other things show the differences > > from time time because we are using different internal types and the middle > > end > > doesn't know that these types are really the same bits. > > > > It is better long term (IMHO) if we have the two types (__float128 and > > _Float128) use the same internal type (which is what is done in patches #2 > > and > > #3). This fixes the other issues that show up, such as creating signaling > > NaNs > > for one internal type, and converting it to the other internal type, loses > > that > > the NaN is signalling. > > > > I see, nice! > > BR, > Kewen -- Michael Meissner, IBM PO Box 98, Ayer, Massachusetts, USA, 01432 email: meiss...@linux.ibm.com
