On Sat, Aug 20, 2022 at 5:29 PM 钟居哲 <juzhe.zh...@rivai.ai> wrote: > > OK. Thank you. I am gonna try it again and fix this in RISC-V port.
The fix is not in the RISC-V port, the fix needs to happen in vect_gen_vector_loop_niters (tree-vect-loop-manip.cc). I described why the code is broken, the second use of const_vf is not connected at all to vf.is_constant (&const_vf) so it will be uninitilized there. Thanks, Andrew > > ________________________________ > juzhe.zh...@rivai.ai > > > From: Andrew Pinski > Date: 2022-08-21 08:18 > To: 钟居哲 > CC: Andreas Schwab; gcc-patches; kito.cheng; andrew; rguenther > Subject: Re: Re: [PATCH] RISC-V: Add runtime invariant support > On Sat, Aug 20, 2022 at 5:06 PM 钟居哲 <juzhe.zh...@rivai.ai> wrote: > > > > Hi, it seems that this warning still report if I revert my patch. Am I > > right? Feel free to correct me. Maybe I need to try it again? > > The warning will not be still there. The reason is NUM_POLY_INT_COEFFS > defaults to 1 which means vf.is_constant (&const_vf) will always > return true and will always set const_vf. > I don't know why the warning does not happen on aarch64-linux-gnu (the > other target where NUM_POLY_INT_COEFFS is set to 2) though; it just > might be slightly different IR which causes the warning mechanism not > to warn. > > Thanks, > Andrew Pinski > > > > > > ________________________________ > > juzhe.zh...@rivai.ai > > > > > > From: Andrew Pinski > > Date: 2022-08-21 07:53 > > To: Andreas Schwab > > CC: juzhe.zhong; gcc-patches; kito.cheng; andrew; Richard Guenther > > Subject: Re: [PATCH] RISC-V: Add runtime invariant support > > On Sat, Aug 20, 2022 at 3:34 PM Andreas Schwab <sch...@linux-m68k.org> > > wrote: > > > > > > This breaks bootstrap: > > > > > > ../../gcc/tree-vect-loop-manip.cc: In function 'void > > > vect_gen_vector_loop_niters(loop_vec_info, tree, tree_node**, > > > tree_node**, bool)': > > > ../../gcc/tree-vect-loop-manip.cc:1981:26: error: 'const_vf' may be used > > > uninitialized [-Werror=maybe-uninitialized] > > > 1981 | unsigned HOST_WIDE_INT const_vf; > > > | ^~~~~~~~ > > > cc1plus: all warnings being treated as errors > > > make[3]: *** [Makefile:1146: tree-vect-loop-manip.o] Error 1 > > > make[2]: *** [Makefile:4977: all-stage2-gcc] Error 2 > > > make[1]: *** [Makefile:30363: stage2-bubble] Error 2 > > > make: *** [Makefile:1065: all] Error 2 > > > > > > This looks like a real uninitialized variable issue. > > I even can't tell if the paths that lead to using const_vf will be > > always set so how we expect GCC to do the same. > > The code that uses const_vf was added with r11-5820-cdcbef3c3310, > > CCing the author there. > > > > Thanks, > > Andrew > > > > > > > > -- > > > Andreas Schwab, sch...@linux-m68k.org > > > GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 > > > "And now for something completely different." > > >
