Thanks, Daniel
I've had to make changes to the test program, as I was using XSI
extensions which aren't implemented on Cygwin. But before I post the
new patch, I noticed that it may be in the wrong directory. There is a
gcc/testsuite/gcc.target/x86_64/abi directory and even a callabi
subdirectory of that. For taxonomic accuracy, I would say it probably
belongs as a subdirectory of .../abi or .../abi/callabi and renamed from
"msabi" to "ms_sysv". Any objections? (It is currently in
gcc/testsuite/gcc.target/i386/msabi.)