Bootstrap failure in libstdc++

[Zack Weinberg]

This with an entirely unmodified tree.  Jan, you're cc:ed because
you're the last person to touch the x86 back end.

/home/zack/src/gcc/vanilla/build/gcc/xgcc -shared-libgcc -B/home/zack/src/gcc/va
nilla/build/gcc/ -nostdinc++ -L/home/zack/src/gcc/vanilla/build/i686-pc-linux-gn
u/libstdc++-v3/src -L/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc+
+-v3/src/.libs -B/home/zack/src/i/gcc_ni/i686-pc-linux-gnu/bin/ -B/home/zack/src
/i/gcc_ni/i686-pc-linux-gnu/lib/ -isystem /home/zack/src/i/gcc_ni/i686-pc-linux-
gnu/include -isystem /home/zack/src/i/gcc_ni/i686-pc-linux-gnu/sys-include -nost
dinc++ -I/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc++-v3/include
/i686-pc-linux-gnu -I/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc+
+-v3/include -I/home/zack/src/gcc/vanilla/libstdc++-v3/libsupc++ -I/home/zack/sr
c/gcc/vanilla/libstdc++-v3/libmath -O2 -g -O2 -g -O2 -D_GNU_SOURCE -fno-implicit
-templates -Wall -Wno-format -W -Wwrite-strings -Winline -fdiagnostics-show-loca
tion=once -ffunction-sections -fdata-sections -c /home/zack/src/gcc/vanilla/libs
tdc++-v3/src/codecvt.cc  -fPIC -DPIC -o .libs/codecvt.o
/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc++-v3/include/i686-pc-
linux-gnu/bits/codecvt_specializations.h: In
   member function `std::__enc_traits::__enc_traits(const char*, const char*, 
   int, int)':
/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc++-v3/include/i686-pc-
linux-gnu/bits/codecvt_specializations.h:84: warning: unused
   parameter `int __ibom'
/home/zack/src/gcc/vanilla/build/i686-pc-linux-gnu/libstdc++-v3/include/i686-pc-
linux-gnu/bits/codecvt_specializations.h:84: warning: unused
   parameter `int __ebom'
/usr/include/bits/mathinline.h: In function `long double logbl(long double)':
/usr/include/bits/mathinline.h:569: error: can't find a register in class `
   FP_TOP_REG' while reloading `asm'
make[4]: *** [codecvt.lo] Error 1

zw