> -----Original Message----- > From: gcc-patches-ow...@gcc.gnu.org [mailto:gcc-patches- > ow...@gcc.gnu.org] On Behalf Of Richard Henderson > Sent: Monday, November 24, 2014 4:57 PM > To: Zhenqiang Chen; gcc-patches@gcc.gnu.org > Cc: Marcus Shawcroft > Subject: Re: [PATCH, AARCH64] Fix ICE in CCMP (PR64015) > > On 11/24/2014 06:11 AM, Zhenqiang Chen wrote: > > Expand pass always uses sign-extend to represent constant value. For > > the case in the patch, a 8-bit unsigned value "252" is represented as > > "-4", which pass the ccmn check. After mode conversion, "-4" becomes > > "252", which leads to mismatch. > > This sort of thing is why I suggested from the beginning that expansion > happen directly from trees instead of sort-of re-expanding from rtl. > > I think you're better off fixing this properly than hacking around it here.
Thanks for the comments. Here was your previous comments: "We could avoid that by using struct expand_operand, create_input_operand et al, then expand_insn. That does require that the target hooks be given trees rather than rtl as input." I want to confirm with you two things before I rework it. (1) expand_insn needs an optab_handler as input. Do I need to define a ccmp_optab with different mode support in optabs.def? (2) To make sure later operands not clobber CC, all operands are expanded before ccmp-first in current implementation. If taking tree/gimple as input, what's your preferred logic to guarantee CC not clobbered? Thanks! -Zhenqiang
