Hi Suwa-san, On Tue, Jan 17, 2023 at 9:25 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > Register-register move instructions that can be easily seen as > unnecessary by the human eye may remain in the compiled result. > For example: > > /* example */ > double test(double a, double b) { > return __builtin_copysign(a, b); > } > > test: > add.n a3, a3, a3 > extui a5, a5, 31, 1 > ssai 1 > ;; be in the same BB > src a7, a5, a3 ;; No '0' in the source constraints > ;; No CALL insns in this span > ;; Both A3 and A7 are irrelevant to > ;; insns in this span > mov.n a3, a7 ;; An unnecessary reg-reg move > ;; A7 is not used after this > ret.n > > The last two instructions above, excluding the return instruction, > could be done like this: > > src a3, a5, a3 > > This symptom often occurs when handling DI/DFmode values with SImode > instructions. This patch solves the above problem using peephole2 > pattern. > > gcc/ChangeLog: > > * config/xtensa/xtensa.md: New peephole2 pattern that eliminates > the occurrence of genral-purpose register used only once and for > transferring intermediate value. > --- > gcc/config/xtensa/xtensa.md | 43 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 43 insertions(+)
This still generates ICE, this time while building libstdc++: during RTL pass: ce3 In file included from build/xtensa-buildroot-linux-uclibc/libstdc++-v3/include/bits/locale_facets.h:2687, from build/xtensa-buildroot-linux-uclibc/libstdc++-v3/include/locale:42, from gcc/libstdc++-v3/src/c++11/locale-inst.cc:38, from gcc/libstdc++-v3/src/c++11/wlocale-inst.cc:35: build/xtensa-buildroot-linux-uclibc/libstdc++-v3/include/bits/locale_facets.tcc: In member function ‘_InIter std::num_get<_CharT, _InIter>::do_get(iter_type, iter_type, std::ios_base&, std::ios_base::iostate&, bool&) const [with _CharT = wchar_t; _InIter = std::istreamb uf_iterator<wchar_t, std::char_traits<wchar_t> >]’: build/xtensa-buildroot-linux-uclibc/libstdc++-v3/include/bits/locale_facets.tcc:686:5: internal compiler error: in df_refs_verify, at df-scan.cc:4009 686 | } | ^ 0x6eb0dc df_refs_verify gcc/gcc/df-scan.cc:4009 0xd19a74 df_insn_refs_verify gcc/gcc/df-scan.cc:4092 0xd1b94c df_bb_verify gcc/gcc/df-scan.cc:4125 0xd1bd77 df_scan_verify() gcc/gcc/df-scan.cc:4246 0xd06ca7 df_verify() gcc/gcc/df-core.cc:1818 0xd06ca7 df_analyze_1 gcc/gcc/df-core.cc:1214 0x1a7287c if_convert gcc/gcc/ifcvt.cc:5858 0x1a73ddd execute gcc/gcc/ifcvt.cc:6026 -- Thanks. -- Max