I noticed that gcc.dg/sms-antideps.c is failing on my IA64 Linux and HP-UX platforms. The failure is:
x.c: In function 'foo': x.c:25: internal compiler error: in gen_sub2_insn, at optabs.c:4640 Please submit a full bug report, with preprocessed source if appropriate. See <URL:http://gcc.gnu.org/bugs.html> for instructions. When I enter gen_sub2_insn the operands I have are: (reg:DI 332 ar.lc) and (const_int 0 [0x0]) It is generate_prolog_epilog (called by sms_schedule) in modulo-sched.c that is trying to generate this subtract. First off: why am I subracting zero? Shouldn't generate_prolog_epilog skip the subtraction if last_stage is zero? I wind up dying because count_reg in this case is "ar.lc" (application register, loop counter) and this register on the IA64 does not allow the subtraction operation on it. All I can do with this register is to do a move into it to initialize it and then use and decrement it in counted loops (the doloop_end insn). How do I explain to the modulo scheduler that it cannot do this optimization? Not doing the subtract when last_stage is zero might make this one test case work but it would leave open the larger problem of possibly generating a subtract instruction on a register (count_reg) that does not allow that operation. Ideas or advise (or patches)? Steve Ellcey [EMAIL PROTECTED]
