https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99114
--- Comment #2 from pipcet at gmail dot com --- (In reply to Eric Botcazou from comment #1) > Please provide a reproducer as documented in https://gcc.gnu.org/bugs I'll try, but please consider investigating this without one. It happens after a very lengthy compilation process (compiling a buggy gcc with a buggy cross-compiler, then compiling JIT code with that, generating a buggy .so, then running _that_, to see incorrect behavior rather than a clear crash), in C++ code, with an out-of-tree backend. On the other hand, it's been investigated, and it's a clear bug with a one-line fix. > > The assumption here is that op0 will be an (and:HI) after the first > > statement (and we assume (subreg:SI (and:HI ... (const_int 3))) is > > defined because of WORD_REGISTER_OPERATIONS) but it's actually > > simplified to be just the (reg:HI 593), and (subreg:SI (reg:HI 593)) > > is not defined. > > Paradoxical registers are defined under specific circumstances though. Thanks, I understand that. This isn't one of them. > > I'm unsure whether this can cause wrong code for in-tree backends or > > backends which don't define WORD_REGISTER_OPERATIONS. > > Well, obviously not for the latter, see the comment just above the code. As I said, I'm unsure. The buggy line of code is executed on other targets, and the condition under which that happens is not !paradoxical_subreg_p. I think it's equivalent, but I don't think that's obvious...
