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[Bug middle-end/42749] [4.5 Regression] -O2 and verify_stmts failed again
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 16 Jan 2010 13:19:25 -0000
- Subject: [Bug middle-end/42749] [4.5 Regression] -O2 and verify_stmts failed again
- References: <bug-42749-9596@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #11 from rguenther at suse dot de 2010-01-16 13:19 -------
Subject: Re: [4.5 Regression] -O2 and verify_stmts
failed again
On Sat, 16 Jan 2010, rakdver at gcc dot gnu dot org wrote:
>
>
> ------- Comment #10 from rakdver at gcc dot gnu dot org 2010-01-16 12:53 -------
> /* Reject a tailcall if the type conversion might need
> 285 additional code. */
> 286 if (gimple_assign_cast_p (stmt)
> 287 && TYPE_MODE (TREE_TYPE (dest)) != TYPE_MODE
> (TREE_TYPE (src_var)))
> 288 return false;
>
> This is suspicious; replacing the weird TYPE_MODE check with
> useless_type_conversion_p fixes the problem.
Correct, but for useless_type_conversion_p we can reject any conversions
in the IL since only !useless_type_conversion_p remain.
I suppose the code was explicitly trying to allow sign-changing
(but not precision changing as it does), or conversion to/from
pointers.
Thus, if you want to go the useless_type_conversion_p route simply
reject all conversions and only allow plain SSA name copies...
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42749