On 10/10/2014 09:39 AM, Jiong Wang wrote: >> (1) Don't bother modifying single_set; just look for a bare SET. >> (2) Tighten the set of expressions we're willing to move. >> (3) Use direct "return false" in the failure case, rather than >> counting a non-zero number of non-constants, etc. >> >> Tested on x86_64, and against Andi's test case (unfortunately unreduced). > > minor nit, after this patch, gcc.target/aarch64/shrink_wrap_symbol_ref_1.c > still not shrink-wrapped under -mabi=ilp32, > the reason is as Pinski reported, LO_SUM is with with RTX_OBJ class, while it > could be treated as expression. > in your fix, if it's RTX_OBJ, and LO_SUM, then the move aborted by return > NULL.
I missed that message. Interesting. I wonder what kind of fallout there would be from changing LO_SUM to RTX_BIN_ARITH, which is what it should have been all along. My guess is that someone looked at HIGH being RTX_CONST_OBJ and thought that LO_SUM should also be a kind of object too. But it's really a lot more like a kind of PLUS. If instead we had a LOW to match HIGH it would have been (plus reg (low symbol)) and thus more obvious. I'll see if I can bootstrap such a change on e.g. sparc or ppc32, which uses lo_sum heavily. > anyway, thanks for the fix, I verified the shrink-wrapping of some hotpot > functions in benchmark on aarch64 are not affected. Thanks for the additional testing. r~
