On 09/18/14 04:26, Richard Sandiford wrote:
Patch 4 should make it possible to relax i386'a CANNOT_CHANGE_MODE_CLASS, solving the missed optimisation that triggered the original thread.gcc/ * config/i386/i386.c (ix86_cannot_change_mode_class): Remove GET_MODE_SIZE (to) < GET_MODE_SIZE (from) test. Index: gcc/config/i386/i386.c =================================================================== --- gcc/config/i386/i386.c 2014-09-15 09:48:11.310438531 +0100 +++ gcc/config/i386/i386.c 2014-09-15 09:48:11.310438531 +0100 @@ -37526,13 +37526,6 @@ ix86_cannot_change_mode_class (enum mach the vec_dupv4hi pattern. */ if (GET_MODE_SIZE (from) < 4) return true; - - /* Vector registers do not support subreg with nonzero offsets, which - are otherwise valid for integer registers. Since we can't see - whether we have a nonzero offset from here, prohibit all - nonparadoxical subregs changing size. */ - if (GET_MODE_SIZE (to) < GET_MODE_SIZE (from)) - return true; } return false;
OK. jeff
