On Thu, Jun 15, 2017 at 05:48:33PM +0800, Paul Hua wrote: > in mips.c: > ... > 3261 (define_insn "*and<mode>3" > 3262 [(set (match_operand:GPR 0 "register_operand" "=d,d,d,!u,d,d,d,!u,d") > 3263 (and:GPR (match_operand:GPR 1 "nonimmediate_operand" > "o,o,W,!u,d,d,d,0,d") > > ^ > 3264 (match_operand:GPR 2 "and_operand" > "Yb,Yh,Yw,Uean,K,Yx,Yw,!u,d")))] > ... > > I do not find "o" in constraints.md and gcc internal. > what is the "o" means? It's in the gccint manual, node "Simple Constraints" (it means offsettable memory). Segher