Yeah, I agree with you that it makes the pass looks confusing that if we are mixing FOR_EACH_BB and for (const bb_info *bb... But Jeff feels happy if I use FOR_EACH_BB so I send a patch to change the iterator form if it doesn't care about the order. In this patch, it's ok for both FOR_EACH_BB and for (const bb_info *bb... So I change it as Jeff suggested.
However, in other places of this pass, for example compute_global_backward_infos function, I want to iterate blocks in reverse order and I must use "for (const bb_info *bb : crtl->ssa->reverse_bbs ())" which can allow me to do the information backward propagation throughly so that I can do the aggressive and fancy optimization. Base on these situations, it will be mixing FOR_EACH_BB and for (const bb_info *bb... in this pass which may make the pass a little bit confusing. juzhe.zh...@rivai.ai From: Richard Sandiford Date: 2022-12-28 19:47 To: Jeff Law via Gcc-patches CC: juzhe.zhong; Jeff Law; kito.cheng\@gmail.com; palmer\@dabbelt.com Subject: Re: [PATCH] RISC-V: Fix ICE of visiting non-existing block in CFG. Jeff Law via Gcc-patches <gcc-patches@gcc.gnu.org> writes: > On 12/27/22 16:11, juzhe.zhong wrote: >> You mean only change to this form you suggested in this patch？ Since in >> all other places of this PASS，I use RTL_SSA framework to iterate >> instructions and blocks. I use RTL_SSA framework to iterate blocks here >> to make codes look more consistent even though they are same here. > The FOR_EACH_BB is used far more widely than the C++ style found in > RTL-SSA so I'd slightly prefer that style. I can see where you're coming from, but what the patch does is preferred for RTL-SSA passes. There is some additional information in rtl_ssa::bb_info compared to the underlying basic_block, and even if this particular loop doesn't use that information, IMO it would be better to avoid mixing styles within a pass. Also, the list that the patch iterates over is in reverse postorder, whereas FOR_EACH_BB doesn't guarantee a particular order. Again, that might not be important here, but it seems better to stick to the “native” RTL-SSA approach. Thanks, Richard
