Hi Richard, 2010/4/23, Richard Guenther <richard.guent...@gmail.com>: > On Thu, Apr 22, 2010 at 6:04 PM, roy rosen <roy.1ro...@gmail.com> wrote: > > Hi Richard, > > > > 2010/4/14, Richard Guenther <richard.guent...@gmail.com>: > >> On Wed, Apr 14, 2010 at 8:48 AM, roy rosen <roy.1ro...@gmail.com> wrote: > >> > Hi All, > >> > > >> > I have implemented some vectorization features in my gcc port. > >> > > >> > In the generated code for this function I can see a scheduling problem: > >> > > >> > int xxx(int* __restrict__ a, int* __restrict__ b) > >> > { > >> > int __restrict__ i; > >> > for (i = 0; i < 8; i++) > >> > { > >> > a[i] = b[i]; > >> > } > >> > return 0; > >> > } > >> > > >> > from asmcons: > >> > > >> > (insn 17 14 18 3 a.c:15 (set (reg:V4HI 105) > >> > (mem:V4HI (reg/v/f:SI 100 [ b ]) [2 S8 A64])) 115 {*movv4hi_load} > >> > (nil)) > >> > > >> > (insn 18 17 19 3 a.c:15 (set (mem:V4HI (reg/v/f:SI 99 [ a ]) [2 S8 A64]) > >> > (reg:V4HI 105)) 116 {*movv4hi_store} (expr_list:REG_DEAD > >> > (reg:V4HI 105) > >> > (nil))) > >> > > >> > (insn 19 18 20 3 a.c:15 (set (reg:V4HI 106) > >> > (mem:V4HI (plus:SI (reg/v/f:SI 100 [ b ]) > >> > (const_int 8 [0x8])) [2 S8 A64])) 115 {*movv4hi_load} > >> > (expr_list:REG_DEAD (reg/v/f:SI 100 [ b ]) > >> > (nil))) > >> > > >> > (insn 20 19 58 3 a.c:15 (set (mem:V4HI (plus:SI (reg/v/f:SI 99 [ a ]) > >> > (const_int 8 [0x8])) [2 S8 A64]) > >> > (reg:V4HI 106)) 116 {*movv4hi_store} (expr_list:REG_DEAD > >> > (reg:V4HI 106) > >> > (expr_list:REG_DEAD (reg/v/f:SI 99 [ a ]) > >> > (nil)))) > >> > > >> > from sched1 - dependecies list: > >> > --- Region Dependences --- b 3 bb 0 > >> > ;; insn code bb dep prio cost reservation > >> > ;; ---- ---- -- --- ---- ---- ----------- > >> > ;; 17 115 3 0 4 1 (2_slots+lsu) : 58 20 > >> > 18 > >> > ;; 18 116 3 1 3 1 (2_slots+lsu) : 58 19 > >> > ;; 19 115 3 1 2 1 (2_slots+lsu) : 58 20 > >> > ;; 20 116 3 2 1 1 (2_slots+lsu) : 58 > >> > ;; 58 101 3 4 1 1 (3_slots+pcu) : > >> > > >> > As you can see, insn 19 is dependant on 18. > >> > I think that this should not happen since the arrays has __restrict__. > >> > It might have something to do with aliasing. > >> > > >> > Are you aware of any kind of problems regarding aliasing and vectors? > >> > Can you think of anything else that might be wrong in my code that > >> > leads gcc to think that there is a dependency between insn 18 and 19? > >> > >> It completely depends on the GCC version you are using. The > >> MEM_EXPRs suggest that it is maybe 4.4 or 4.5 based? Because > >> they are not existant. Try recent trunk which should work fine. > >> > >> Richard. > >> > >> > Thanks, Roy. > >> > > >> > > > > I have taken 4.5.0 and I still get the same problem. > > Do you have any ideas? Shouldn't the restrict tell the compiler that > > there is no dependency between these insns? > > It doesn't work for 4.5.0 due to PR42617. > > Richard. > > > Thanks, Roy. > > >
I took snapshot 4.6-20100424 (is this version ok?) and the problem still occurs when I am looking at the vectorized version of the code. It seems ok in the nonvectorized version. What might be the problem? Thanks, Roy.