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[Bug tree-optimization/46590] [4.6/4.7/4.8 Regression] long compile time with -O2 and many loops


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46590

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steven at gcc dot gnu.org

--- Comment #23 from Steven Bosscher <steven at gcc dot gnu.org> 2012-08-21 09:42:42 UTC ---
(In reply to comment #13)
> The I/O parts of the FRE cost are due to value-numbering stores in
> visit_reference_op_store.  They can be drastically cut by an equivalent
> of (not generating code)
> 
> Index: trans-io.c
> ===================================================================
> --- trans-io.c  (revision 167111)
> +++ trans-io.c  (working copy)
> @@ -1670,6 +1670,7 @@ build_dt (tree function, gfc_code * code
>    gfc_init_block (&post_iu_block);
> 
>    var = gfc_create_var (st_parameter[IOPARM_ptype_dt].type, "dt_parm");
> +  gfc_add_modify (&block, var, build_constructor (TREE_TYPE (var), NULL));
> 
>    set_error_locus (&block, var, &code->loc);
> 

You didn't post/commit this, but it looks like a reasonable change to me.


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