Re: [PATCH 204/236] final.c: Use rtx_sequence

[Jeff Law <law at redhat dot com>]

On 08/06/14 11:23, David Malcolm wrote:
> gcc/
> 	* final.c (get_attr_length_1): Replace GET_CODE check with a
> 	dyn_cast, introducing local "seq" and the use of methods of
> 	rtx_sequence.
> 	(shorten_branches): Likewise, introducing local "body_seq".
> 	Strengthen local "inner_insn" from rtx to rtx_insn *.
> 	(reemit_insn_block_notes): Replace GET_CODE check with a
> 	dyn_cast, strengthening local "body" from rtx to rtx_sequence *.
> 	Use methods of rtx_sequence.
> 	(final_scan_insn): Likewise, introducing local "seq" for when
> 	"body" is known to be a SEQUENCE, using its methods.
So presumably a dyn_cast isn't terribly expensive here?  I guess I'm a 
bit fuzzy on whether or not we agreed to allow using dynamic casts?!? 
Doesn't that have to check the RTTI info which I would think would be 
considerably more expensive than just checking the code.  Or am I 
missing something here?

Jeff