seen with r244382

../../../../src/libgo/go/runtime/trace.go: In function 'runtime.dump.pN23_runtime.traceStackTable':
../../../../src/libgo/go/runtime/trace.go:731:1: error: fallthru edge after unconditional jump in bb 2
 func (tab *traceStackTable) dump() {
 ^
../../../../src/libgo/go/runtime/trace.go:731:1: error: wrong number of branch edges after unconditional jump in bb 2
../../../../src/libgo/go/runtime/trace.go:731:1: internal compiler error: verify_flow_info failed
0x13439ed verify_flow_info()
	../../src/gcc/cfghooks.c:260
0x1d445f9 checking_verify_flow_info
	../../src/gcc/cfghooks.h:198
0x1d445f9 try_optimize_cfg
	../../src/gcc/cfgcleanup.c:2988
0x1d4471d cleanup_cfg(int)
	../../src/gcc/cfgcleanup.c:3152
0x1d44961 execute
	../../src/gcc/cfgcleanup.c:3281
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.

Makefile:3268: recipe for target 'runtime.lo' failed
make[10]: *** [runtime.lo] Error 1
make[10]: Leaving directory '/<<PKGBUILDDIR>>/build/s390x-linux-gnu/32/libgo'
Makefile:2689: recipe for target 'all-recursive' failed
make[9]: *** [all-recursive] Error 1

gcc configured with --enable-languages=c,ada,c++,go,fortran,objc,obj-c++ --prefix=/usr/lib/gcc-snapshot --program-prefix= --enable-shared --enable-linker-build-id  --disable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libsanitizer --disable-libquadmath --enable-plugin --with-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch=zEC12 --with-long-double-128 --enable-multilib --enable-checking=yes --build=s390x-linux-gnu --host=s390x-linux-gnu --target=s390x-linux-gnu