on 2022/12/9 06:04, Michael Meissner wrote: > On Wed, Dec 07, 2022 at 03:55:41PM +0800, Kewen.Lin wrote: >> Hi Mike, >> >> on 2022/12/7 14:44, Michael Meissner wrote: >>> On Tue, Dec 06, 2022 at 05:36:54PM +0800, Kewen.Lin wrote: >>>> Hi Mike, >>>> >>>> Thanks for fixing this! >>>> >>>> Could you help to elaborate why we need to disable it during libgcc >>>> building? >>> >>> When you are building libgcc, you are building the __mulkc3, __divkc3 >>> functions. The mapping in the compiler interferes with those functions, >>> because at the moment, libgcc uses an alternate IEEE 128-bit type. >>> >> >> But I'm still confused. For __mulkc3 (__divkc3 is similar), >> >> 1) with -mabi=ieeelongdouble (TARGET_IEEEQUAD true, define >> __LONG_DOUBLE_IEEE128__), >> the used types are: >> >> typedef float TFtype __attribute__ ((mode (TF))); >> typedef __complex float TCtype __attribute__ ((mode (TC))); >> >> 2) with -mabi=ibmlongdouble (TARGET_IEEEQUAD false, not >> __LONG_DOUBLE_IEEE128__ defined), >> the used types are: >> >> typedef float TFtype __attribute__ ((mode (KF))); >> typedef __complex float TCtype __attribute__ ((mode (KC))); >> >> The proposed mapping in the current patch is: >> >> + >> + if (id == complex_multiply_builtin_code (KCmode)) >> + newname = "__mulkc3"; >> + >> + else if (id == complex_multiply_builtin_code (ICmode)) >> + newname = "__multc3"; >> + >> + else if (id == complex_multiply_builtin_code (TCmode)) >> + newname = (TARGET_IEEEQUAD) ? "__mulkc3" : "__multc3"; >> >> for 1), TCmode && TARGET_IEEEQUAD => "__mulkc3" >> for 2), KCmode => "__mulkc3" >> >> Both should be still with name "__mulkc3", do I miss anything? >> >> BR, >> Kewen > > The reason is due to the different internal types, the value range propigation > pass throws an error when we are trying to build libgcc. This is due to the > underlying problem of different IEEE 128-bit types within the compiler. >
But this is the reason why we need patch #2 and #3, not the reason why we need the special handling for building_libgcc in patch #1, right? 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? > The 128-bit IEEE support in libgcc was written before _Float128 was added to > GCC. One consequence is that you can't get to the complex variant of > __float128. So libgcc needs to use the attribute mode to get to that type. > > But with the support for IEEE 128-bit long double changing things, it makes > the > libgcc code use the wrong code. > > /home/meissner/fsf-src/work102/libgcc/config/rs6000/_mulkc3.c: In function > ‘__mulkc3_sw’: > /home/meissner/fsf-src/work102/libgcc/config/rs6000/_mulkc3.c:97:1: internal > compiler error: in fold_stmt, at gimple-range-fold.cc:522 > 97 | } > | ^ > 0x122784f3 fold_using_range::fold_stmt(vrange&, gimple*, fur_source&, > tree_node*) > /home/meissner/fsf-src/work102/gcc/gimple-range-fold.cc:522 > 0x1226477f gimple_ranger::fold_range_internal(vrange&, gimple*, tree_node*) > /home/meissner/fsf-src/work102/gcc/gimple-range.cc:257 > 0x12264b1f gimple_ranger::range_of_stmt(vrange&, gimple*, tree_node*) > /home/meissner/fsf-src/work102/gcc/gimple-range.cc:318 > 0x113bdd8b range_query::value_of_stmt(gimple*, tree_node*) > /home/meissner/fsf-src/work102/gcc/value-query.cc:134 > 0x1134838f rvrp_folder::value_of_stmt(gimple*, tree_node*) > /home/meissner/fsf-src/work102/gcc/tree-vrp.cc:1023 > 0x111344cf > substitute_and_fold_dom_walker::before_dom_children(basic_block_def*) > /home/meissner/fsf-src/work102/gcc/tree-ssa-propagate.cc:819 > 0x121ecbd3 dom_walker::walk(basic_block_def*) > /home/meissner/fsf-src/work102/gcc/domwalk.cc:311 > 0x11134ee7 substitute_and_fold_engine::substitute_and_fold(basic_block_def*) > /home/meissner/fsf-src/work102/gcc/tree-ssa-propagate.cc:998 > 0x11346bb7 execute_ranger_vrp(function*, bool, bool) > /home/meissner/fsf-src/work102/gcc/tree-vrp.cc:1084 > 0x11347063 execute > /home/meissner/fsf-src/work102/gcc/tree-vrp.cc:1165 > Please submit a full bug report, with preprocessed source (by using > -freport-bug). > Please include the complete backtrace with any bug report. > See <https://gcc.gnu.org/bugs/> for instructions. > make[1]: *** [/home/meissner/fsf-src/work102/libgcc/shared-object.mk:14: > _mulkc3.o] Error 1 > make[1]: Leaving directory > '/home/meissner/fsf-build-ppc64le/work102/powerpc64le-unknown-linux-gnu/libgcc' > make: *** [Makefile:20623: all-target-libgcc] Error 2 > >>> I have a patch for making libgcc use the 'right' type that I haven't >>> submitted >>> yet. This is because the more general fix that these 3 patches do impacts >>> other >>> functions (due to __float128 and _Float128 being different in the current >>> compiler when -mabi=ieeelongdouble). >>> > > The patch is to use _Float128 and _Complex _Float128 in libgcc.h instead of > trying to use attribute((mode(TF))) and attribute((mode(TC))) in libgcc. > 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. > 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
