------- Comment #3 from amodra at bigpond dot net dot au 2009-08-16 03:05 ------- Created an attachment (id=18374) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18374&action=view) aims to teach gcc that rotate/shift insn input register's high bits are ignored
This patch is aimed at the "79 other redundant clrldi", removing 59 cases on rotate/shift input. I'm not particularly happy with it due to hack for LOAD_EXTEND_OP zero_extends. Before I discovered that particular problem, fwprop seemed a natural place to teach gcc about insn inputs. If we don't leave those zero_extends alone, some rotate insns will take their input directly from the load, while other insns still need the zero_extend. This prevents combine from removing the zero_extend on loads. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41081
