http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46391
--- Comment #3 from Roy Rosen <roy.1rosen at gmail dot com> 2010-11-11 08:03:57 UTC --- It happens also on i386 with ./cc1 -O3 a.c -fdump-rtl-all -funroll-loops -fsched-verbose=8 -fschedule-insns: In asmcons: (insn 16 15 17 4 a.c:5 (set (reg:SI 72 [ vect_var_.26 ]) (mem:SI (plus:SI (reg/v/f:SI 74 [ c ]) (reg:SI 70 [ ivtmp.42 ])) [0 MEM[(char * restrict)vect_p.22]+0 S4 A32])) 50 {*movsi_internal} (nil)) (insn 17 16 134 4 a.c:5 (set (mem:SI (plus:SI (reg/v/f:SI 75 [ d ]) (reg:SI 70 [ ivtmp.42 ])) [0 MEM[(char * restrict)vect_p.27]+0 S4 A32]) (reg:SI 72 [ vect_var_.26 ])) 50 {*movsi_internal} (expr_list:REG_DEAD (reg:SI 72 [ vect_var_.26 ]) (nil))) (insn 134 17 135 4 a.c:5 (set (reg:SI 82 [ vect_var_.26 ]) (mem:SI (plus:SI (plus:SI (reg/v/f:SI 74 [ c ]) (reg:SI 70 [ ivtmp.42 ])) (const_int 4 [0x4])) [0 MEM[(char * restrict)vect_p.22]+0 S4 A32])) 50 {*movsi_internal} (nil)) and in sched1: ;; ====================================================== ;; -- basic block 4 from 16 to 198 -- before reload ;; ====================================================== ;; --------------- forward dependences: ------------ ;; --- Region Dependences --- b 4 bb 0 ;; insn code bb dep prio cost reservation ;; ---- ---- -- --- ---- ---- ----------- ;; 16 50 4 0 35 4 decodern,p2 : 198 196 195 185 175 165 155 145 135 17 ;; 17 50 4 1 31 1 decoder0,(p4+p3) : 198 196 194 184 174 164 154 144 134 ;; 134 50 4 1 31 4 decodern,p2 : 198 196 195 185 175 165 155 145 135 ;; 135 50 4 2 27 1 decoder0,(p4+p3) : 198 196 194 184 174 164 154 144 There should not be any dependency between 17 (store) and 134 (load). BTW, I failed building i386 from the current snapshot so I used an old one. (../../gcc-4.6-20101106/gcc/config/i386/bdver1.md:528: unknown mode `V4DF' ../../gcc-4.6-20101106/gcc/config/i386/bdver1.md:528: following context is `0 "r egister_operand")' )