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[Bug tree-optimization/32826] Reduction into a global variable causes a Load Hit Store Hazard (for the Cell)
- From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 26 Jul 2007 17:02:16 -0000
- Subject: [Bug tree-optimization/32826] Reduction into a global variable causes a Load Hit Store Hazard (for the Cell)
- References: <bug-32826-6528@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from pinskia at gcc dot gnu dot org 2007-07-26 17:02 -------
(In reply to comment #2)
> (In reply to comment #2)
> Just want a clarification:
> I see you're compiling on PPU (since you're using -maltivec).
> Does this problematic also on SPU?
No because extraction from a vector is a simple rotate.
> Does SPU has this LHS hazard?
No because there is no store queue on the SPU.
>
> Another question:
> lwz r0,-20(r1) <---- LHS hazard
> stw r0,lo16(_e)(r2)
>
> The problem here is these 2 insns, right?
No, it is the load after the store to the same address:
stvewx v1,0,r2
lwz r0,-20(r1) <---- LHS hazard
r2 at this point is equal to -20(r1).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32826