https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71847
--- Comment #2 from Segher Boessenkool <segher at gcc dot gnu.org> --- Author: segher Date: Fri Oct 28 20:56:28 2016 New Revision: 241664 URL: https://gcc.gnu.org/viewcvs?rev=241664&root=gcc&view=rev Log: combine: Improve change_zero_ext (fixes PR71847) This improves a few things in change_zero_ext. Firstly, it should use the passed in pattern in recog_for_combine, not the pattern of the insn (they are not the same if the whole pattern was replaced). Secondly, it handled zero_ext of a subreg, but with hard registers we do not get a subreg, instead the mode of the reg is changed. So this handles that. Thirdly, after changing a zero_ext to an AND, the resulting RTL may become non-canonical, like (ior (ashift ..) (and ..)); the AND should be first, it is commutative. And lastly, zero_extract as a set_dest wasn't handled at all, but now it is. This fixes the testcase in PR71847, and improves code generation in some other edge cases too. PR target/71847 * combine.c (change_zero_ext): Handle zero_ext of hard registers. Swap commutative operands in new RTL if needed. Handle zero_ext in the set_dest. (recog_for_combine): Pass *pnewpat to change_zero_ext instead of PATTERN (insn). Modified: trunk/gcc/ChangeLog trunk/gcc/combine.c
