https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83565
--- Comment #29 from Jim Wilson <wilson at gcc dot gnu.org> --- (In reply to Sergei Trofimovich from comment #28) > 1. Is it directly visible for you from RTL dumps which bits GCC assumes as > non-zero or you just know RTL invariants? I had to patch gcc locally to > verify RTL prediction by adding printfs into print_pattern to get the idea > how it works: I stepped through combine in gdb to find the problem. > 2. Does gcc have any validation mode that could have caught this error after > code generation and checking against RTL invariant? We have some compile-time and run-time checking code, but nothing that would catch a problem like this. We do have the regression testsuite which requires manually adding testcases that get miscompiled, and hopefully prevents them from getting miscompiled again.
