https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64722
--- Comment #13 from David Malcolm <dmalcolm at gcc dot gnu.org> --- (In reply to Ilya Enkovich from comment #11) > (In reply to David Malcolm from comment #10) > > which led to investigating this code in ix86_conditional_register_usage: > > 4394 j = PIC_OFFSET_TABLE_REGNUM; > > 4395 if (j != INVALID_REGNUM) > > 4396 fixed_regs[j] = call_used_regs[j] = 1; > > and line 4396 is bizarrely only called on the 2nd iteration, not the 1st, > > which led me to investigate "PIC_OFFSET_TABLE_REGNUM", and discover what > > appears to be the root cause, as described in comment #1. > > Now I see. The problem also is in ix86_conditional_register_usage that > relies on pic_offset_table_rtx value. As I said EBX value is used only to > estimate costs for middle-end. Thus we shouldn't fix reg here if pseudo pic > register is used and correct code would be: > > @@ -4388,7 +4388,7 @@ ix86_conditional_register_usage (void) > > /* The PIC register, if it exists, is fixed. */ > j = PIC_OFFSET_TABLE_REGNUM; > - if (j != INVALID_REGNUM) > + if (j != INVALID_REGNUM && !ix86_use_pseudo_pic_reg ()) > fixed_regs[j] = call_used_regs[j] = 1; > > /* For 32-bit targets, squash the REX registers. */ Ilya: I can't speak to the correctness of the above code or patch, but r220044 fixes the original issue I ran into. Do you want me to keep this bug open, or should we track the above in a separate PR?
