https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66565
--- Comment #2 from David Edelsohn <dje at gcc dot gnu.org> --- The high-level consensus at the GNU Cauldron 2015 GCC Cost Model BoF is: 1) Create gimple_costs() instead of creating potentially invalid fragments to query rtx_costs(). 2) Cost models can utilize GCC Pass phase to set expectations for optimization changes by later passes. 3) Cost models should be queried for relative comparisons of the potential instruction sequences, not for comparisons against magic constants.
