------- Comment #3 from xuepeng dot guo at intel dot com 2009-02-12 08:50 ------- The numbers 27 and 28 mean extended SSE registers xmm10 and xmm11. Because we turned on the option "-mno-sse", according to the explanation of FIXED_REGISTERS in i386.h I think that setting fixed_regs[27] and fixed_regs[28] to 1 is reasonable. According to the explanation of CALL_USED_REGISTERS "1 for registers not available across function calls. These must include the FIXED_REGISTERS and also any registers that can be used without being saved.", when the call_abi equals MS_ABI I think leaving call_used_regs[27] and call_used_regs[28] as 1 is better.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38891