bad dwarf frame in stgRun.c when compiled with with gcc on mac and assembled by as/gcc/clang (aka apple clang assembler)

for current master, if i build on a mac / OSX high sierra environment with CC set as any flavor of recent GCC rather than apple clang, i get a failure "no open frame" when as (aka apple clang / apple llvm acting as the assembler) is run on the .s file produced by stgRun.c (rts/StgCRun.c to be exact)

this error message seems to come from https://github.com/llvm-mirror/llvm/blob/da4a2839d80ac52958be0129b871beedfe90136e/lib/MC/MCStreamer.cpp#L221

https://gist.github.com/cartazio/8cbfb3305e1daa4f7ffc3f6bb90a2891 has the gcc and clang style assembly for

/usr/local/bin/gcc-8 -fno-stack-protector -DTABLES_NEXT_TO_CODE -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -Irts/dist/build -Irts/dist/build/./autogen -fno-common -U__PIC__ -D__PIC__ -x assembler -c /var/folders/py/wgp_hj9d2rl3cx48yym_ynj00000gn/T/ghc22029_0/ghc_1.s -o rts/dist/build/StgCRun.debug_o

this is example asm for the the debug way