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Re: [PATCH GCC8][31/33]Set range information for niter bound of vectorized loop
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Bin Cheng <Bin dot Cheng at arm dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, nd <nd at arm dot com>
- Date: Thu, 11 May 2017 13:02:03 +0200
- Subject: Re: [PATCH GCC8][31/33]Set range information for niter bound of vectorized loop
- Authentication-results: sourceware.org; auth=none
- References: <VI1PR0802MB2176DFC4FDDB5C365B2F8E3FE7190@VI1PR0802MB2176.eurprd08.prod.outlook.com>
On Tue, Apr 18, 2017 at 12:54 PM, Bin Cheng <Bin.Cheng@arm.com> wrote
> Hi,
> Based on vect_peeling algorithm, we know for sure that vectorized loop must iterates at least once.
> This patch sets range information for niter bounds of vectorized loop. This helps niter analysis,
> so iv elimination too.
> Is it OK?
niters_vector = force_gimple_operand (niters_vector, &stmts, true, var);
gsi_insert_seq_on_edge_immediate (pe, stmts);
+ /* Peeling algorithm guarantees that vector loop bound is at least ONE,
+ we set range information to make niters analyzer's life easier. */
+ if (TREE_CODE (niters_vector) == SSA_NAME)
+ set_range_info (niters_vector, VR_RANGE, build_int_cst (type, 1),
+ fold_build2 (RSHIFT_EXPR, type,
+ TYPE_MAX_VALUE (type), log_vf));
if all of niters_vector folds to an original SSA name then
niters_vector after gimplification
is not a new SSA name and thus you can't set range-info on it.
Likewise for the other case where LOOP_VINFO_NITERS is just an SSA name.
Richard.
> Thanks,
> bin
> 2017-04-11 Bin Cheng <bin.cheng@arm.com>
>
> * tree-vect-loop-manip.c (vect_gen_vector_loop_niters): Refactor.
> Set range information for vector loop bound variable.
> (vect_do_peeling): Ditto.