On Thu, 9 Jun 2011, Richard Guenther wrote:
>
> This is a complementary fix for the leslie3d problem. For functions
> without a regular exit (for example one that exits with exit (0))
> we do not apply noreturn predictors. The following patch notices
> that edges to noreturn calls are still unlikely if they have
> exactly one predecessor and is not fallthru. In the leslie3d
> case this avoids predicting the edges to STOP but still correctly
> predicts the edges to the exceptional noreturn functions.
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu, ok for trunk?
It regresses
FAIL: gcc.target/i386/umod-3.c scan-assembler-times divb 1
Richard.
> Thanks,
> Richard.
>
> 2011-06-09 Richard Guenther <rguent...@suse.de>
>
> * predict.c (tree_bb_level_predictions): For functions with
> no regular exit still predict the edge to a block with a noreturn
> function as not taken if it is not a fallthru edge.
>
> Index: gcc/predict.c
> ===================================================================
> --- gcc/predict.c (revision 174746)
> +++ gcc/predict.c (working copy)
> @@ -1613,10 +1613,18 @@ tree_bb_level_predictions (void)
>
> if (is_gimple_call (stmt))
> {
> - if ((gimple_call_flags (stmt) & ECF_NORETURN)
> - && has_return_edges)
> - predict_paths_leading_to (bb, PRED_NORETURN,
> - NOT_TAKEN);
> + if ((gimple_call_flags (stmt) & ECF_NORETURN))
> + {
> + if (has_return_edges)
> + predict_paths_leading_to (bb, PRED_NORETURN,
> + NOT_TAKEN);
> + else if (single_pred_p (bb))
> + {
> + edge e = single_pred_edge (bb);
> + if (!(e->flags & EDGE_FALLTHRU))
> + predict_edge_def (e, PRED_NORETURN, NOT_TAKEN);
> + }
> + }
> decl = gimple_call_fndecl (stmt);
> if (decl
> && lookup_attribute ("cold",
>
>
--
Richard Guenther <rguent...@suse.de>
Novell / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer
