Ping. This should be relatively simple to review. Many thanks.
> -----Original Message----- > From: gcc-patches-ow...@gcc.gnu.org [mailto:gcc-patches- > ow...@gcc.gnu.org] On Behalf Of Ian Bolton > Sent: 08 May 2014 18:36 > To: gcc-patches > Subject: [PATCH, AArch64] Use MOVN to generate 64-bit negative > immediates where sensible > > Hi, > > It currently takes 4 instructions to generate certain immediates on > AArch64 (unless we put them in the constant pool). > > For example ... > > long long > ffffbeefcafebabe () > { > return 0xFFFFBEEFCAFEBABEll; > } > > leads to ... > > mov x0, 0x47806 > mov x0, 0xcafe, lsl 16 > mov x0, 0xbeef, lsl 32 > orr x0, x0, -281474976710656 > > The above case is tackled in this patch by employing MOVN > to generate the top 32-bits in a single instruction ... > > mov x0, -71536975282177 > movk x0, 0xcafe, lsl 16 > movk x0, 0xbabe, lsl 0 > > Note that where at least two half-words are 0xffff, existing > code that does the immediate in two instructions is still used.) > > Tested on standard gcc regressions and the attached test case. > > OK for commit? > > Cheers, > Ian > > > 2014-05-08 Ian Bolton <ian.bol...@arm.com> > > gcc/ > * config/aarch64/aarch64.c (aarch64_expand_mov_immediate): > Use MOVN when top-most half-word (and only that half-word) > is 0xffff. > gcc/testsuite/ > * gcc.target/aarch64/movn_1.c: New test.
