http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55154
--- Comment #2 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-01 10:40:37 UTC --- (In reply to comment #1) > Started with http://gcc.gnu.org/viewcvs?view=revision&revision=192719 > The interesting thing is that this happened before, definitely in r190614, > afterwards was fixed in some commit, and 190777 was fine. As the test name implies, it was PR46254. The problem there was that %rbx is declared as fixed reg for "-fpic -mcmodel=large" case. Fixed regs are unavailable to RA, so we have to handle it in a special way. This PR shows a deficiency in how subregs are handled in LRA. The test lives and dies by correct subreg handling in the RA. For reference, pre-LRA allocator resolved allocation for problematic insn with: Reloads for insn # 10 Reload 0: reload_in (DI) = (subreg:DI (reg:TI 60 [ i.1 ]) 0) reload_out (DI) = (reg:DI 4 si) AREG, RELOAD_OTHER (opnum = 0) reload_in_reg: (subreg:DI (reg:TI 60 [ i.1 ]) 0) reload_out_reg: (subreg:DI (reg:TI 4 si [65]) 0) reload_reg_rtx: (reg:DI 0 ax) Reload 1: reload_in (DI) = (subreg:DI (reg:TI 60 [ i.1 ]) 8) reload_out (DI) = (reg:DI 5 di) DREG, RELOAD_OTHER (opnum = 1) reload_in_reg: (subreg:DI (reg:TI 60 [ i.1 ]) 8) reload_out_reg: (subreg:DI (reg:TI 4 si [65]) 8) reload_reg_rtx: (reg:DI 1 dx) Reload 2: reload_in (DI) = (subreg:DI (reg:TI 60 [ i.1 ]) 0) reload_out (DI) = (scratch:DI) GENERAL_REGS, RELOAD_OTHER (opnum = 5) reload_in_reg: (subreg:DI (reg:TI 60 [ i.1 ]) 0) reload_out_reg: (scratch:DI) reload_reg_rtx: (reg:DI 38 r9) Reload 3: reload_in (DI) = (subreg:DI (reg:TI 60 [ i.1 ]) 8) CREG, RELOAD_FOR_INPUT (opnum = 6) reload_in_reg: (subreg:DI (reg:TI 60 [ i.1 ]) 8) reload_reg_rtx: (reg:DI 2 cx)
